The Best Dish Soap

Dishwashing liquid, the kind you squirt into your sink to do dishes by hand, is something that most of us have in our kitchens. After over 60 hours of research we think Seventh Generation Dish Liquid is the one you want. Out of the 20 different hand dishwashing detergents we lab tested, it has the best combination of cleaning power, safety, price, and social responsibility. It also smells good if that’s your thing and comes unscented if it isn’t.

Last Updated: August 15, 2014
Updated with our longer-term observations after using Seventh Generation for more than six months. One of our editors switched from Dawn and found the biggest difference between the two is that Seventh Generation rinses more easily from the sponge and dishes, so it doesn't leave that mildewy sponge smell behind.
Expand Previous Updates
May 27, 2014: We found more research that shows buying dish soap with triclosan as an ingredient is a really bad idea. See our updated "Other ingredients of concern" section for why Minnesota has already banned any product with triclosan from being sold in the state, and why New York is considering the same.

Dawn Ultra is excellent at cleaning, too, and it’s a good pick if you don’t mind dyes, synthetic fragrances, or animal testing. But it and the Seventh Generation are safe, reasonably priced, and will get the job done better than the rest.

What to look for in a dish detergent

First, a dish detergent has to get oil and grease off your dishes. Almost all dish liquids on the market can do this to varying degrees—it’s those degrees that matter. You might also be looking for a detergent that is easier on your conscience and has the fewest worrisome ingredients.

How we picked

There are a fair number of dish detergent guides out there, but there are no great ones. Consumer Reports says that all detergents they tested will get your dishes clean and recommended Ajax because it works well and is cheap. Companies such as Good Housekeeping, America’s Test Kitchen, and Grist compared how well different detergents scrubbed off caked-on grease and food. However, it’s extremely difficult to bake the exact same amount of grease on a number of pans and also make sure you use the same amount of force to scrub it off. In addition, both Good Housekeeping and Grist only looked at ‘green’ detergents, not any conventional ones. They also gave points for how well dish soaps foamed, but that’s not an indicator of how well a detergent can clean (we explain below).

There are also some ingredient guides out there, such as the Environmental Working Group’s (EWG) Guide to Healthy Cleaning, and Good Guide, which are both less than ideal. The EWG often does not give specific reasons for its ratings. For example, they will say things such as “May contain ingredients with potential for respiratory effects; acute aquatic toxicity; cancer,” but do not say what the concerning ingredients are. In addition, they don’t list any sources or link to data. The Good Guide does a better job of breaking down ingredients, but their sources are not great (mostly Wikipedia). Neither outlet tests to see which product works the best.

Lacking a good, comprehensive guide, we decided to do our own tests.

Lacking a good, comprehensive guide, we decided to do our own tests.
To figure out which detergents to test, we looked at the best sellers at Amazon.com, the top scorers at Good Guide, ones that topped the testing charts at Consumer Reports, Good Housekeeping, Real Simple, America’s Test Kitchen (aka Cook’s Illustrated) and Grist, and some been-around-for-ages brands that our moms and grandmas used. We took both conventional detergents and some ‘green’ detergents with fewer ingredients that some people are concerned about. We also made sure to include a few ‘free and clear’ varieties that don’t have dye or fragrance added. We ended up selecting 20 dish liquids for testing:

Ajax Super Degreaser Dish Liquid, Lemon – a best buy from both Consumer Reports.

Better Life DISH IT OUT – recently shot up Amazon’s bestseller list, presumably because it was featured on the TV show Shark Tank. This one doesn’t have any of the common cleaning agents that some people are concerned about, and we wanted to see how these compare to more traditional dish liquids.

Biokleen – a common green dish liquid which some people love and others hate. We wanted to form our own opinions.

CitraSolv – This was a bit of a personal pick. I use the brand’s all purpose cleaner and love it; was curious about the dish liquid.

Dawn Direct Foam – winner of Consumer Reports’ tests.

Dawn Platinum Power Clean – recommended by Real Simple. They call it the dish liquid with the most muscle.

Dawn Ultra Dishwashing Liquid, Original Scent, Blue – the classic Dawn; #1 on Amazon’s bestseller list for dish liquids. Also recommended by Cook’s Illustrated.

Dawn Ultra Pure Essentials Dishwashing Liquid (no dyes) – the version of the above without dyes. Wanted to see how it compared with the classic stuff.

Eco-me dish detergent – recommended by and bestselling at Gimme the Good stuff, another without common cleaning agents.

Ecover Natural Dishwashing Liquid – one of the top-selling green brands at Amazon; it was Grist’s pick and Consumer Reports’ green pick.

GrabGreen in Red Pear with Magnolia – this and another dish liquid were in a tie for best fragrance from Real Simple.

Ivory Ultra Classic Scent – fared well in Consumer Reports’ tests.

Joy Ultra Concentrated – fared well in Consumer Reports’ tests.

Method, clementine – Method offers refills, so you don’t have to buy a whole new bottle when you want more. And according to Amazon, people really love the way this stuff smells in a variety of fragrances. Clementine seemed to be the most popular, so that’s what we went with.

Mrs. Meyer’s Clean Day Dish Soap, Lemon Verbena Scent – ditto on the cult following for fragrance on this one, plus also a popular green dish liquid.

Original Palmolive Ultra – the classic for no more dishpan hands! Thanks, Madge. This brand has been around for ages, and we wanted to see how one of the grandpa detergents measured up.

Palmolive OxyPlus – version of above but with OxyClean, a bleach alternative. Wanted to see how it compared to the regular version.

Planet Ultra – Good Housekeeping pick for green dish liquids, and on the top of the Good Guide’s list.

Seventh Generation Dish Liquid – the bestselling green dish liquid according to Amazon, and a strong #3 overall. Also highly recommended by Cook’s Illustrated, and Real Simple’s pick for gentlest on skin.

Up & Up fresh scent (Target store brand) – we wanted to test a generic brand along with the others, and this is what I had in my cabinet. Plus it says on the bottle, “Compare to Dawn Ultra!” So we did.

Some of the dish liquids that we tested. Photo by Alex Farris.

Some of the dish liquids that we tested. Photo by Alex Farris.

Things we dismissed

We did not test any dish liquids that were labeled as antibacterial, since they contain triclosan. I go into more detail below, but the FDA isn’t sure that antibacterials actually help get rid of germs, and they might be hurting our health. We also didn’t test the different fragrances of the same type of detergent, since we assumed that these would have the same basic formula and performance. (Fragrances don’t have any role in the chemistry that gets our dishes clean.) One exception to this was comparing Original Dawn to Dawn Pure Essentials, since they have slightly different formulas. We also didn’t test a Dawn non-ultra variety, since the company’s PR person told me that they “weren’t supporting the brand” any more, and you can only get those at Dollar General stores. (Although you can still get that at Amazon, you mightn’t be able to for much longer.)

How we tested

When setting up a testing method, we ran into two problems. As I mentioned above, it’s difficult to bake on a set amount of grease to a dish or pan. Second, short of building a scrubbing robot, it’s also hard to wash a dish with the same amount of pressure and strokes each time. So that makes the most obvious test—just washing some dirty dishes—not really work. Instead, we listened to surfactant expert Brian Grady, the director of the Institute for Applied Surfactant Research at the University of Oklahoma. Surfactants, short for surface active agents, are the soap-like molecules in cleaning products that bind oil and water together so they can be washed away. (For more details on how, see our explainer below.)

Brushing the oil/food coloring mixture onto the plate. Purple gave the best contrast. Photo by Alex Farris.

Brushing the oil/food coloring mixture onto the plate. Purple gave the best contrast. Photo by Alex Farris.

The less oil remaining on the plate, the better the detergent is at cleaning.
I took some vegetable oil, mixed in some oil-soluble food coloring, and brushed a thin layer on a plate. I let this sit for five minutes, then placed two oil-coated dishes in the bottom of a tub containing 5 mL of detergent and 10 L of approximately 70°F water. I made sure to add the detergent after the tub was filled and mixed gently to discourage foaming. Surfactants work by agitation, so I beat the mixture with a hand-held egg beater for two minutes. Then I pulled the dish out, laid it flat, and eyeballed how much oil was remaining on the plates. I then took the cleaner plate (in most cases the two plates were virtually identical) and compared them to the control.1 The less oil on the plate, the better the detergent is at cleaning.

Agitating the water with an egg beater in one of the tests. Photo by Alex Farris.

Agitating the water with an egg beater in one of the tests. Photo by Alex Farris.

This method works in a couple of ways. It measures how the detergent by itself can work to clean away oil, which is the point of a dish detergent. It also leaves out the scrubbing factor, which might tend to make people think that their detergent is working harder than it is. Because really, if you scrub hard enough with any detergent, your dish will come clean. However, since I was eyeballing the remaining oil, and not using a machine to tell me precisely how much food coloring was left behind, I had to put the detergents into relative categories.

The categories: excellent (5-10% oil remaining), very very good (10-15% oil left), very good (15%), good (20%), okay (25%), and poor (35%). For reference, the control had about 40% of the oil left on the plate.

What we found

There were two clear winners in the cleaning tests: Seventh Generation and Dawn. Both of these detergents topped the pack, and we categorized them as excellent. As I said above, Seventh Generation is our ultimate pick because the company doesn’t use dyes or synthetic fragrances that may contain potentially harmful compounds, and it doesn’t test on animals. But Dawn works great, too. And both are reasonably priced. Depending on what your priorities are, either is a great pick.

However, the runners-up were not far behind. The following detergents fell into the very very good category: Dawn Ultra Pure Essentials Dishwashing Liquid (no dye)2, Joy Ultra Concentrated, Planet Ultra, Citri-solv, and Dawn Direct Foam. These were also good cleaners, and you honestly probably couldn’t go wrong with any of these either, especially if one has a scent that you particularly love. (Personally, I kind of want to spread the Citri-solv behind my ears for perfume.) The Dawn Direct Foam also deserves a special mention because it’s meant to be applied directly to your sponge instead of squirted in the water. I tried doing some oily dishes this way too, and the foam actually lasted quite a while. As a result, you could potentially use A LOT less water if you do your dishes with this.

Pulling plates out of the Ivory testing bath. Photo by Alex Farris.

Pulling plates out of the Ivory testing bath. Photo by Alex Farris.

I should mention Biokleen, which was the only one that fell into the Poor category.
The rest of the detergents fell into the middle of the pack. However, I should mention Biokleen, which was the only one that fell into the Poor category. After cleaning with this dish liquid, about 35% of the oil was still on the plate. This is barely better than plain water, which had 40% of the oil left. Unless you like dirty dishes, avoid Biokleen.

Long-term test notes

Senior Editor Ganda Suthivarakom has been using the Seventh Generation liquid soap for six months and loves it. Prior to switching to our pick, she used Dawn in her kitchen for many, many years. The Seventh Generation liquid has a great viscosity and, unlike a lot of so-called “green” soaps, it matches Dawn’s grease scrubbing power—a little goes a long way. She finds that the big difference between the two is that Seventh Generation rinses more easily from the sponge and dishes, pretty much eliminating disgusting mildewy sponge smell. For her, that’s reason enough to make a permanent switch to Seventh Generation.

How to do dishes

I tested dish liquids in room temperature water and put the detergent in the water after the sink was filled. (Remember, suds aren’t an indicator of cleaning power.3) Right about now, you may be wondering if you’ve been doing your dishes wrong for years. Don’t worry. I asked Grady-the-surfactant-man and both Dawn and Seventh Generation if there is a preferred way to do dishes. Grady says that which order you add detergent and water doesn’t really matter, as long as the detergent is mixed into the water well. “In theory less foam is better,” he says, “but the effect is so small as to be negligible.”4 But adding the detergent first does help with getting it evenly distributed. Grady says that he adds detergent just before turning off the tap. Soaking also helps, but about five minutes is long enough in most cases.

Both Dawn and Seventh Generation said that customers should do dishes in a way that works best for them, and that they don’t have any specific recommendations. So basically, you could do your dishes naked with sardines in your ears5, as long as you use their product.

At home, temperature does not matter too much. Hot water will help dissolve grease better, but it won’t kill bacteria on your plates. According to the FDA’s rules for restaurants (pdf), you need the water to be around 171°F to sanitize dishes. That’s really hot.6 Most people can only stand water temperatures around 110°F, and most people keep their home hot water heaters set at around 135°F or so. So washing your dishes in really hot water at home won’t do much if you want to kill bacteria. For restaurants, the FDA requires that employees wash dishes in 110°F water, rinse well, then submerge the dishes for at least 30 seconds in a sanitizer solution. According to a study from a few years ago, washing your dishes in cooler water than 110°F will still kill bacteria, as long as you soak them in a sanitizer afterwards. Bleach works, and you don’t need much. A tablespoon in a gallon of water is the MAXIMUM that the FDA allows for surfaces that will touch food (pdf), and a teaspoon in a gallon of water is probably enough. Let dry completely before using the dishes, or rinse them off with clean water after sanitizing. But if you don’t want to use a sanitizer, you can minimize the amount of bacteria on your dishes by washing them as soon as possible after use. Bacteria tends to cling to the tines of forks and plastic dishes, so give these special attention.

Are ‘green’ dish detergents really green?

According to some data gathered for me by Professor Jennifer Field, an environmental and molecular toxicologist at Oregon State University, the main surfactants in dish detergents, sodium lauryl sulfate (SLS) and sodium lauryl ethyl sulfate (SLES) (more about these here), both decompose in sewage treatment plants and soil (where your wastewater ends up if you have a septic system). In addition, once they’re in the soil, they don’t move to other places. As such, these compounds aren’t a hazard to the environment. However, dumping ANY soap directly into a water system is a bad idea, regardless of which surfactant is in the bottle. All of them will kill fish.

I go into more detail below, but dish detergents have little to no phosphate, a potential water pollutant these days. So that’s out as an environmental hazard.

It looks like one of the few difference between ‘green’ detergents and conventional dish detergents is where their ingredients come from.
It looks like one of the few difference between ‘green’ detergents and conventional dish detergents is where their ingredients come from. According to Cara Bondi, the Research and Development manager at Seventh Generation, their detergents only use ingredients that come from plants. Instead of cleaning agents that come from petrochemicals7, their detergents are made from coconut and palm oil (sustainable palm oil, she says).8 Seventh Generation also does not use synthetic dyes, which may not biodegrade. They also do not use any Volatile Organic Compounds (VOCs), which can deteriorate air quality and lead to smog. Bondi says that all these things add up to a smaller carbon footprint for their detergents.

How much does this matter? Well, it’s unclear. I can’t find any scientific studies on the environmental impact of oil-based versus plant-based detergents. Companies that sell ‘green’ detergents say it does matter, but they want to sell their detergents. According to the American Cleaning Institute, a group made up of companies that make cleaning products and their raw ingredients, there are environmental tradeoffs to using both renewable and non-renewable sources for cleaning products, so it tends to even out. They say, while plant-based cleaning agents “are derived from a renewable resource, they typically produce more air emissions and solid waste. Petrochemical surfactants, on the other hand, consume more total energy, since they are made from resources used as energy.” Unfortunately, they do not link to a source for this research.

Making this even more complicated is an interesting experiment run by Rebecca over at greenbabyguide.com. In her quest to find the best dish detergent, she tested a number of different brands over a year in her kitchen. She found that with green detergents, she tended to have to use more to get her dishes clean. Because of this, she tended to use the bottle up faster, which created more plastic bottle waste and cost her more money. She found that based on how long it lasted, using Biokleen green dish detergent would cost her four times as much than the generic brand, and produce about six more empty bottles per year.

So is it worth it to buy ‘green’ dish detergent? The answer is a bit hazy. Based on everything I could find, it’s unlikely to have much of an impact, if any.

However, there is one difference that may be important: ‘green’ dish detergents tend not to test their products on animals. I don’t think this falls under an environmentally-friendly heading, per se, but I do consider it a plus. So that earns points for our ultimate top pick, Seventh Generation.

Surfactants and a potentially hazardous byproduct

There are two main surfactants that most companies put in their dish liquid, sodium lauryl sulfate (SLS) and sodium lauryl ethyl sulfate (SLES). As you can probably tell by their names, the two are very closely related. They have similar properties, too. SLS cleans a bit better and is foamier, but is also more likely to form soap scum and is more irritating to skin.9  SLES, also known as sodium laureth sulfate, is just SLS transformed into a compound that doesn’t cause soap scum. Chemists create SLES through a process called ethoxylation, which is basically just adding chemical fragments called ethoxy groups to the grease-loving part of the surfactant molecule. This makes the surfactant less likely to interact with the dissolved minerals in tap water, thus producing less soap scum.

When you make SLES from SLS, the reaction creates a small amount of a compound called 1,4-dioxane. Manufacturers can remove this contaminant from surfactants through a process called vacuum stripping, but amounts of it can still end up in the finished bottle of detergent. And because it’s a contaminant and not an ingredient, detergent companies aren’t required to say on the label that it’s in there.10

1,4-dioxane is described by the EPA as a probable human carcinogen. This means that there aren’t any definitive tests on humans, but the compound has caused cancer in lab animals at high concentrations. Scientists also know that 1,4-dioxane can be absorbed through the skin, although it’s more likely to cause harm if inhaled.

Now the important thing to remember here (and with all chemical exposure) is that the dose makes the poison. No compound is toxic in and of itself; how much a person is exposed to is what’s important. For example, the toxic dose of a chemical such as arsenic is much much lower than the toxic dose of a chemical such as water.11 But let’s get to the question that people are worried about.

Will 1,4-dioxane in dish detergent harm me?

Quick answer for those who don’t want to read this whole section: it’s incredibly unlikely.

Quick answer for those who don’t want to read this whole section: it’s incredibly unlikely.
And here’s why. According to the toxicological profile of 1,4-dioxane put out by the Agency for Toxic Substances and Disease Registry in 2012, the National Academy of Sciences says that polysorbate, a food additive, should not have more than 10 parts per million (ppm) for 1,4-dioxane. That’s 10 molecules of 1,4-dioxane per one million molecules of other stuff in polysorbate. The EPA says that drinking water with 4 ppm of 1,4-dioxane for a day or 0.4 ppm for 10 days is not expected to harm a child. The FDA has a limit of 10 ppm for 1,4-dioxane in the spermicide N-9 and also 10 ppm for compounds that end up in dietary supplements.

In summary, it seems the popular limit for 1,4-dioxane is 10 ppm. And that’s for products that you ingest or otherwise put inside your body. There aren’t any guidelines for 1,4-dioxane levels in cosmetics or cleaning products right now, but the FDA has done some skin absorption studies. They found that 1,4-dioxane can be absorbed in the skin in certain cases, such as when it’s found in lotion. However, they found that the compound evaporates really fast, which means that a very small amount makes it into the skin, even when these products remain on the skin for hours. Since there’s a very small amount found in products such as lotions to begin with, only a very very small amount might actually be absorbed.

In short: the FDA is not really worried about it. They are monitoring it, though, and they advise manufacturers on minimizing the amount of 1,4-dioxane in their products.

Let’s get back to dish detergent. Most conventional dish detergents, such as Dawn, Ajax, and the like, use both SLES and SLS in their detergent formulations. And most ‘green’ detergents, such as Seventh Generation, Ecover, and Mrs. Meyer’s Clean Day, use only SLS. Remember, 1,4-dioxane is more likely to be in products that contain SLES.12

In 2008 and 2009, the Organic Consumers Association tested a bunch of different shampoos, body washes, and dish detergents for 1,4-dioxane.13 The products they tested were by no means extensive, but they did look at several different dish detergents.14 Many ‘green’ dish detergents tested had levels of 1,4-dioxane around 100 ppm or so, but the manufacturers got these down to non-detectable amounts (below 0.2 ppm) when they were retested a year later. For the dish detergents they tested that had a detectable amount of 1,4-dioxane,  the average amount was just below 3 ppm, and number is skewed high by the 8.6 ppm reading of the Palmolive Pure & Clear Sparkling Fresh. Everything else was below 3 ppm, well below the popular limit.15

Remember how much dish detergent you use when you’re doing dishes? About a teaspoon in a sink full of water. I decided to find out if this amount of 1,4-dioxane when washing dishes is enough to register any concern.

I have a pretty standard size sink in my house. I filled one side up with the amount of hot water I’d typically use to do a load of dishes, and it came out to about 2.6 gallons, or 10 liters (L). It took one teaspoon, or 5 milliliters (mL), of Target’s generic brand to produce about three inches of foam on top, about how much I’d use if I were doing a load of dishes. I want to get the amount of detergent in water into ppm so I can directly compare it to the limits the government agencies put on it, so I’ll need the weight per volume of the detergent. Different brands vary a tiny bit, but it’s about 1 gram (g) per mL, the same as water.16

equationSince ppm is mg/L, we can say that this concentration of detergent in water is 500 ppm. Because I don’t know the concentration of 1,4-dioxane in this detergent, I’m going to use a high estimate of 10 ppm, based on the findings by the OCA. For simplicity’s sake, I’m going to write out ppm as a fraction. That’s 10 molecules of 1,4-dioxane in every 1 million molecules of detergent, which looks like this:

equation2The last number on the bottom is a billion. That makes 5 parts per billion of 1,4-dioxane in a sinkful of water. Not much.17 You would need to do about 2,000 sinkfuls of dishes and absorb all of it into your skin to get to the 10 ppm level. However, if you’re still concerned about it, avoid dish detergents with any ingredients containing the –eth suffix, plus PEG, which stands for polyethylene glycol. And if that’s not enough, you could don a pair of classic yellow rubber gloves to do your dishes. As a bonus, you would avoid dishpan hands. Win.

Other ingredients of concern

Our first concerns: phthalates—a class of chemicals known as plasticizers, which make hard plastics more flexible and therefore harder to break. Phthalates are found in hundreds of different products. You may have heard about them because there’s been some recent press about getting phthalates phased out of use in children’s toys. How exactly they affect human health, if at all, is not clear. They have caused harm to the reproductive systems of lab animals, but there haven’t been many human studies. CDC researchers have found phthalates (or metabolites) in many people they tested, leading them to say that exposure is “widespread.” The FDA says that they don’t pose a safety risk the way they’re used in cosmetics right now, but they’re keeping an eye on it.

In dish detergent, phthalates tend to be used in the fragrance mixture. But you won’t see anything that looks like a phthalate on the outside of a dish detergent bottle—per FDA rules, companies are not required to list the ingredients of a fragrance. However, choosing ‘fragrance-free’ dish detergent will probably help you steer clear of this one. And many detergents such as Seventh Generation that don’t use phthalates tend to advertise that on the label.

Another compound to look out for is triclosan. It’s used as an antibacterial agent in many products, including dish detergent. And because it’s also used as a pesticide, this one is required to be on the label. As I mentioned above, the FDA says antibacterial soaps with triclosan do NOT work better than regular soap. There isn’t any evidence that they kill more germs than regular old soap, and some studies say that the use of this compound is leading to more resistant bacteria. You’ve probably heard of these superbugs, and they have the potential to make us really, really sick.18 In addition, scientists have found that people with triclosan in their noses, which can get in through ingestion or skin exposure, are more likely to have staph germs up there too. In response to these types of data, the FDA recently gave companies that make antibacterial soap a year to prove that it’s beneficial. Not wanting to wait for this info, Minnesota has banned products with triclosan from being sold in the state, and New York is considering similar bills. So maybe skip anything that says ‘antibacterial’ on the label. Because of this, we didn’t test any of these types of dish detergent.

Phosphates are pretty common but too much of them can spell trouble for water systems, namely by algal bloom.
The last on the list of the concerning chemicals trifecta are phosphates. Phosphates are pretty common—they make up the backbone of our DNA, for example—but too much of them can spell trouble for water systems, namely by algal bloom. Basically, algae in the water snaps up this yummy yummy food and reproduces like crazy, choking out other plants, fish, and aquatic wildlife.

It used to be a problem, but in August 2010 seventeen states passed a ban on high amounts of phosphates in lawn fertilizers and dish detergent (which includes handwashing dish liquid). Because of the nightmarish logistics that would go along with having phosphate containing detergent in some states but not others, companies just cut back on the amount of phosphate in all their products. More recently, Procter & Gamble, who makes Dawn and Tide, said that they’re going to cut back on phosphates in their products worldwide, phasing them out completely over the next two years. As such, it’s unlikely that your dish detergent contains phosphates. To be sure, check the label.

How soap works

Why do we need to use soap on our dishes at all? Because oil and water don’t mix. Water molecules are made up of an oxygen atom with two hydrogen atoms on either side (H₂0). The elements stick together because they share little electrical charges knowns as electrons. Oxygen’s a bigger electron hog than hydrogen and pulls the electrical charge towards it, away from the hydrogens. Because of this unequal electron sharing, the water molecule has one part with a slightly negative charge (the oxygen) and another charged slightly positive (the hydrogens).

Oil, on the other hand, is mostly made up of carbon and hydrogen atoms. These are much better at sharing their electrons evenly, and as a result don’t have an overall electrical charge.

When you get oil and water together, both liquids bead up and try to minimize their contact with each other. The charged bits repel the non-charged bits, and vice-versa. Both liquids kind of fold up into themselves to try to minimize contact with one another. It is for this reason that you can rinse a plate gunked up with grease all day long, and while some might sloosh off just from the blast of water, to get it really clean you need a way to make the two different molecules mix. That’s soap.

Soap is pretty dang nifty. It’s made up of two opposite parts: one part that’s neutral so it can mix with oil, and one part that’s charged so it can mix with water. It looks like this:

sodium_laurylWhen soap molecules encounter a blob of grease in water, the neutral parts interact with the oil while the charged parts interact with the water. It ends up forming a structure called a micelle,19 which is kind of a spherical20 blob. It looks like this:

micelleThe heads of the soap molecules point out, towards the water. And the tails point inward, towards the soap. By pulling the grease and water together, the soap allows water to dissolve the grease, which allows us to rinse it away. Victory!

Dish detergent isn’t technically soap

Though we call it soap, chemists call it sodium stearate. The trouble is, sodium stearate actually isn’t that great at cleaning. It often reacts with the dissolved minerals in tap water to form a white solid. It’s this solid that sticks to the walls of your shower and the sides of your wine glass, otherwise known as soap scum. When a molecule of soap forms a molecule of soap scum, that’s one fewer molecule that can form the micelles around grease, so it not only mucks up dishware and tiles, but it does not clean as well.

To get around the soap scum problem, scientists developed other soap-like molecules that don’t form scum as readily, because they don’t react as well with the types of minerals typically found in water. These are surfactants, short for surface active agent.

Surfactants are in all types of cleaning products from toothpaste to shampoos to dish detergents. A detergent, ultimately, is a cleaning solution that contains one or more surfactants. According to surfactant expert Brian Grady, detergent companies put a combination of surfactants into detergents for foaming, cleaning, and not producing soap scum. They also put the smallest amount of surfactant in the bottle possible—they’re trying to make the detergent clean well and cheaply. Also, soaps and detergents tend to be irritants—all surfactants are designed to make oil rinse away in water, which includes the oils in your skin, so they can make your skin dry and itchy. Some soaps and detergents also are alkaline, so they might produce a burning sensation if you’re sensitive.21

By the way, dish soap works on seemingly low-grease foods. For example, even a vegetable like a dry-roasted pepper contains a ton of natural oils. And burnt-on sugar is not all that molecularly different than oil; it’s mainly hydrocarbons, which are dissolved by the hydrophilic part of soap.

Specialty detergents

Perusing liquid dish detergents on Amazon brings up a few dish detergents that are marketed specially towards baby items, such as bottles, breast pump parts, and toys. But are these really any different from regular dish liquids? The three most prevalent baby targeted brands are Palmolive, Seventh Generation, and Dapple. Palmolive Baby has fewer ingredients than the original Palmolive dish liquid, and uses a different main surfactant.22 The baby variety also has three surfactants instead of two, and a pH control agent instead of stabilizers to help keep it fresh. The only problem with the Palmolive Baby dish liquid is that many people complain about the residual fragrance (according to reviews on Amazon, soap.com, and drugstore.com). Palmolive doesn’t make a fragrance-free baby dish liquid at the time of this writing.

Seventh Generation uses the exact same ingredients in its baby dish liquid as the original, just in slightly different concentrations.
Seventh Generation uses the exact same ingredients in its baby dish liquid as the original, just in slightly different concentrations. According to Brandi Thomas, their media relations person, the company increased the amount of some of the cleaning agents “to get at really tough, biological oils,” presumably such as fatty breast milk. Of course, much food residue is made up of biological oil. She also said that some of their employees use the baby dish liquid for really greasy pans. I then asked the obvious question, which is if this works so well on grease, why don’t they just make this formula the regular dish liquid? Thomas said that the company didn’t really think that people need this stronger formula for everyday use, since it is more expensive, but it is good for use on bottle and breast pump parts. And yes, it is more costly: Seventh Generation baby is almost twice as expensive per ounce as the regular Seventh Generation, 21 cents versus 11 on Amazon.

Dapple, which only makes baby-marketed products, also has a dish liquid.  Dapple Baby comes in a fragrance-free variety, and does not contain any SLS or SLES, instead using lauryl glucoside23 as a cleaning agent. The bottle promotes “baby-safe ingredients” and has a sticker on the bottle that claims “0% toxins.” This seems to imply that other dishwashing detergents are not baby-safe, and that Dapple is harmless, neither of which are true. Using the word “toxins” is also a bit strange, since the definition of a toxin is a biologically produced poison, like a snake venom or the compound that causes botulism. When I pointed this out to the company, their representative, Kelsey O’Connor, told me that they mean that the detergent has the following attributes: it contains no SLS, no SLES, no parabens, no 1,4-dioxane, no dyes, no artificial fragrances, no phthalates, and the bottles are BPA-Free. I again pointed out that none of these things are toxins, and while saying the detergent has 0% toxins is technically true24 this might mislead customers to think that the ingredients are harmless, which is not true, and surely they don’t mean to mislead their customers? This was Dapple’s official response:

“The claim “no toxins” is completely true and forthright – not a single ingredient in our products is a toxin, and we disclose all ingredients to make sure everyone knows exactly what’s in there. The fact that something does not contain toxins, however, does not necessarily mean it is edible. As a result, we also clearly mark all products with a safety warning to that end.”

So there you go, folks. Dapple is your source for officially botulism-free dish liquid.

Deadly nerve toxins aside, do you really need a separate dish liquid for washing baby bottles and breast pump parts? We decided to do our own tests to find out. I followed the same protocol for the regular detergents: put a thin layer of oil on a plate, then submerge it in 10 L of 70°F water with 5 mL of detergent mixed in, and beat it with an egg beater for two minutes. Then I compared the baby detergents to water, the regular Seventh Generation, and Dawn. And guess what? Both Palmolive baby and Dapple removed more oil than the regular Seventh Generation and Dawn. Dapple was the best, leaving only about 5% of the oil on the plate. Palmolive baby left behind about 10% of the oil. Seventh Generation baby did not do as well, and left about 25% of the oil on the plate, a worse performance than the regular Seventh Generation dish liquid.

But are these detergents worth it? Reviews from multiple sources sing the praises of these dish liquids, but they are more expensive. Dapple rings up at about $0.26 per ounce (although through that source you do have to pay shipping). The price of the Palmolive Baby seems to be all over the place online, but I got a 10 ounce bottle for $2.50 at my local Wal-Mart. At that price, it might be worth it to keep some for bottles and breast pump parts. But I would try out regular detergents first. If they don’t work for you, then maybe it’s time to bring in the big guns.

Wrapping it up

You can’t beat the cleaning power of Seventh Generation, and it comes with a side of social responsibility.  And for just the main course, Dawn Ultra is also a good pick.

Footnotes:

1. The control was plates that had received the same treatment, but with plain water instead of a water/detergent mixture. Jump back.

2. For those wondering why this one didn’t do as well as the original Dawn Ultra, it has a slightly different formula. Jump back.

3. It’s easy to figure out how well a detergent is going to clean your dishes. You just pour some in the sink, fill it up with water, and see how much it foams, right? Wrong! This is a really common misconception. Some surfactants foam more than others. But how much they foam has nothing to do with how well they clean. And likewise, the absence of foam does not mean that your detergent is not cleaning. So don’t get duped by the pretty white suds on top. They will only lead you astray. Jump back.

4. I only did it this way in my testing to maximize the difference between the plain water and the detergents. Ditto for the 70°F water. This let me judge the detergents better, because it was easier to tell the difference between them. Jump back.

5. We don’t recommend this. Jump back.

6. According to the American Burn Association, sticking your hand in 155°F water will cause a third degree burn in one second. (pdfJump back.

7. According to Grady, the oil industry makes more money each year from selling cleaning agent materials than they do from gas. Jump back.

8. They don’t make their own cleaning agents; they buy them, but she wouldn’t tell me from where. Jump back.

9. Remember, how foamy or bubbly a detergent is has nothing to do with how well it cleans. Grady says that some surfactants are just better at foaming than others. Jump back.

10. Cleaning products aren’t drugs, cosmetics, or foods, so they aren’t regulated by the FDA. And the guidelines from the EPA only require that pesticides be listed on the label, which is why you won’t see a list of ingredients on most bottles of dish liquid (although some companies, such as Seventh Generation, do include ingredients). The EPA has recently started Design for the Environment labeling, in which companies can have a special label put on their products if they meet the EPA’s guidelines. These are supposed to have safer ingredients, and it seems as if this is the EPA’s answer to improving transparency, rather than making it a law. Jump back.

11. Death by drinking too much water is called hyponatremia, the literal translation of which is “not enough salt in the blood.” This condition can lead to swelling of the brain tissue, which leads to coma and eventual death. That being said, you have to drink A LOT of water to get to this point, over one liter per hour for a normal healthy person. More about it hereJump back.

12. I chatted with Maia James over at Gimme the Good Stuff, who put together this safe product guide for dish detergents.  While the guide uses language that seems to imply there is a risk where there may not necessarily be, it’s pretty extensive in breakdown of ingredients in detergents. One thing she did bring up during our talk, and that she mentions here, is that some people think that SLS might be a carcinogen. She says she can’t find any evidence of this and neither can I. Maia links to the Snopes.com page about it, which talks about the possible origins of this rumor. The Environmental Working Group also classifies SLS as a low overall hazard, and not a cancer riskJump back.

13. Unfortunately, the link to the actual test results still appears to be broken, despite my informing two separate people at the OCA of this. It took multiple and emails for them to send me a copy, but I can pass them along to anyone interested. Jump back.

14. Dawn was not among them, but Ellen Losey, their PR person, told me “all Procter & Gamble household cleaning product will be at or below 25 ppm by the end of 2013. Many are already below 10 ppm.” However, she said that the company did not want to disclose the exact amount in their dish liquid. You can reread the same basic statement hereJump back.

15. The only exception to this is Mrs. Meyer’s Clean Day Liquid Dish Soap, which came in at 204 ppm of 1,4-dioxane. However, I talked to Pam Helms, the Chief Innovation Officer at Mrs. Meyer’s Clean Day. She says that they’ve reformulated their dish liquid since then, and their internal tests show no detectable level of 1,4-dioxane. Jump back.

16. Generally, the density of dish liquid is slightly higher. You can layer water on top of dish liquid, and it will drop to the bottom of a sink filled with water. We’re using 1 g/mL here as an approximation. Jump back.

17. I discounted the amount of 1,4-dioxane that might be found in my tap water, just because a) I don’t know how much it is, b) it might not be any at all since having a limit of something in water does not necessarily mean that there is any of it in your water, and c) it’s going to be different for everybody on based where you live and water quality. Jump back.

18. For a peek at what antibiotic resistant bacteria might lead to, please read Maryn McKenna’s article on the post-antibiotic future. Guaranteed to cause nightmares. Jump back.

19. This is the same basic structure that the cells in our bodies have as well, except our cell membrane are made up of phospholipids instead. Jump back.

20. A sphere is the most structurally stable type of shape, which is why it’s found so often in nature. Just ask a soap bubble. Jump back.

21. Soap is traditionally made with sodium hydroxide, aka lye, which is very very alkaline. If you’ve seen or read Fight Club, you know what this can do to your skin. If you spill some on yourself (I have), it actually makes your skin slimy. That’s your fat dissolving. Yum. Jump back.

22. Good old sodium laureth sulfate instead of ammonium pareth sulfate. According to Brian Grady, the surfactant expert, these are pretty much the same and clean about as well as each other. Jump back.

23. Also known as decyl glucoside. It’s made from glucose and an alcohol. Not a lot is known about this surfactant, but it’s supposed to be mild on skin. Jump back.

24. And therefore complies with the Fair Packaging and Labeling ActJump back.

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Sources

  1. The Best Green Cleaners, Good Housekeeping
  2. Madaline Sparks, The Best Dish Soap for Your Home, Real Simple, November 2012
  3. Liquid Dish Detergent, Cook's Illustrated, February 2012
  • http://www.picsofcelebrities.net/blog/2012/05/08/voice-season-finale Cromulent

    It would be nice from now on to have both the official recommendation and then one produced by ignoring the so-called “social responsibility” requirement.

    • Michael Zhao

      This has that? Get Dawn Ultra. I’m confused. What are you asking for here?

      • http://toomuchnick.com Nick

        I think Cromulent means that it’d be good if other Sweethome/Wirecutter articles had what this article had: The best cell phone and also the best socially responsible cell phone, etc.

        • Michael Zhao

          That is the opposite of what his comment implies.

  • Pavan Samtani

    Currently a $5 coupon can be used for ordering Seventh Generation at Amazon, and if you subscribe, you get an additional 5% off. Just placed an order! Great write up (as always)!

    • Kevin

      where is the coupon?

      • Pavan Samtani

        These sort of deals tend to sell out fast at Amazon, but from what I can tell its a common deal there. If available again look out for a ‘Clip It’ button just below the main description.

  • http://www.richardsnotes.org Richard

    I’ve used Kirkland (Costco) dish soap for years. I love it. Why not include it here?

  • GretaSchlachter
  • Kevin

    Is there a recommendation for dishwasher detergent?

    • Leigh Krietsch Boerner

      We’re working on that. It’s a doozy though, so it might be awhile.

      • R Jones

        Any update on dishwasher detergent? I understand it’s very complicated and may vary between dishwasher but with that said, a recommendation would be a good place to start. Thanks.

        • http://thewirecutter.com/ tony kaye

          Sorry I misunderstood. We’re working on it, but nothing yet unfortunately no.

  • ClementinaFennelly

    The Soap is using for clean the Clothes and Dress when Dress is totally Dirty.
    https://www.facebook.com/pages/Inexpensive-Way-To-Shed-Kilos/515928108525951

  • barongreenback

    Is 5ml the recommended dose for a standard tub? Does more work better? Would be useful to know. I bet most people use far more than 5ml per wash.

    • Leigh Krietsch Boerner

      There’s not really a recommended amount to use. Some companies say something like “use one firm squeeze,” and others don’t say anything at all. 5 mL is actually kind of a lot of detergent. It’s one teaspoon, which is a pretty prolonged squeeze. Brian Grady was surprised I was using that much–he said it was a lot too.

      It follows logically that more detergent will work better, but 5 mL or less is plenty. Unless you have some seriously greasy dishes, it should be enough to do a whole sinkful of dishes. Using more than a big squeeze under normal conditions is probably a waste of money.

      • Ashe

        I use 0.5-1.0cc onto a sponge (liquid soap). This is what I’ve been doing for the past ten years. Is that an incorrect method? Or is Dawn just trying to sell more products with its Dawn Direct Foam line?

        • Leigh Krietsch Boerner

          According to Dawn, that’s not incorrect. They’ll take your money however they can get it. :)

          I’ve recently moved into a house without a dishwasher (!), so I’ve been doing dishes by hand. I’ve been using the Dawn direct foam right on the sponge method, as well as doing dishes the more conventional way, ie squirt it in the water. I think the benefit of the Direct foam is that foaming pump top. It aerates the detergent, so you don’t use as much on the sponge. Because of this, it dissolves better on the sponge, and you don’t have to add any water besides getting the sponge damp beforehand. Putting detergent on the sponge without the foaming pump means you have to work it into the sponge a bit better, and it takes some more work to make it dissolve.

          That being said, if what you’re doing works for you, by all means don’t change! I haven’t tried this yet, but I’m willing to bet that putting another detergent inside the Dawn Direct foam dispenser will have the same effect. The Direct foam detergent is a little bit thinner than regular dish detergent, but other than that the formulation is about the same. You could even try it with one of those foaming hand soap dispensers. Okay, I’m curious now, I think I’ll go try this later.

  • Jonathan Renich

    Great article, originally from Oregon, now living in Ulaanbaatar, Mongolia. My company is the official distributor for Seventh Generation here. It’s great to have articles like this to back up our claims of superiority. =) Here the fight is against the giant Fairy, not Dawn, but results would probably be similar. It’s worth noting that that from Amazon you can buy 6 25oz SG for $18 or 2 (yes TWO) 24oz Dawn dish soap bottles for $14. Kind of makes the decision for you doesn’t it? Bravo SG and bravo The Sweet Home for such a great writeup.

    • http://www.phasedma.com Anthony

      Maybe you can explain how this product is better for the environment. All the water being treated is going to the same exact place, which means it all has to be treated the same.

      Maybe if you are camping, and tossing the dirty dish soap on the ground it should be a consideration, but I don’t see how it’s a useful consideration in home with a public sewer (where I’m sure most of this product is being used).

      • jrenich

        You have a point there Anthony, public sewer is there anyways and water treatment is going to be the same. I would say the argument would be that if everyone was using a similar product the water wouldn’t have to be treated so harshly which is a bit wishful thinking, but it could be compared to: should we use plastic bags because trash cans are available anyways or ban them to reduce waste?

        I’m on a home septic system with a leach field so it certainly makes sense for us.

        I would think there must be some environmental differences in manufacturing as well comparing a 95% bio-based product to a synthetic product but I don’t have details on that.

        Health-wise, it’s not an environmental issue per-say but my family members complain of rashes and cracked skin and sensitivity to fumes with Dawn/Fairy and no such problems with Seventh Generation soaps.

        In the future, as with trash solutions, and fuel efficient/low impact vehicles vs higher polluting ones it may just be that if a certain population of people are using them then general environmental changes (waste water treatment) can take place. It has to start somewhere and while using it on a city system today might not make any difference at how the waste water plant treats water you will at least know you aren’t adding to that plants load and the health benefits themselves are enough to consider switching IMO.

  • MercedesKnudson

    I think that I will use it dish soap one time for knowing a quality is good or not .
    http://ladermaniquehelps.tumblr.com/

  • TammaraDarrigo

    Due to use it soap for clean the Utensils and other things .
    http://truburnplustrial.net/

  • Monika Mons

    my husband just have brought me big box of dish soap from Hungary like this http://www.bpg-fine.lt/lt/dishwashing-liquid/produkts/ind-plovikliai-fine what do you think? is it good or we should’nt buy it again?

  • Edward Fingerhands

    I STRONGLY disagree with this selection, for the sole reason that 7th generation causes my fingernails to smell really weird (even when I don’t use it as hand soap).

  • Brailleyard

    I thoroughly laughed aloud upon clicking the ‘sardines in ears’ link. Thank you.

  • Will

    I have tried Dawn, but I always find that it makes my sponges (and through contact with the sponge my hands) smell awful. Never have that problem with Palm Olive. Can anyone comment on Seventh Generation’s sponge smell factor?

    • http://thewirecutter.com/ tony kaye

      Getting some info on this now!

    • Ganda Suthivarakom

      Sweethome editor here. Since I started using Seventh Generation, I’ve found that I don’t get the mildewy sponge smell I used to get with Dawn. Dawn has a tendency to take a long time to rinse clean from the sponge, which causes that disgusting stink. Seventh Gen cuts grease just as well but rinses away much better. I haven’t had to prematurely toss smelly sponges with it. Being fastidious about rinsing and squeezing your sponge after every use also helps.

  • LMHwx

    So, how did Dawn Platinum score?

    • http://thewirecutter.com/ tony kaye

      Here is what our researcher had to say!

      “It came in the very good group. So it worked well, but there were others that worked better.”

      Hope this helps!

      • LMHwx

        Thanks!

        • http://thewirecutter.com/ tony kaye

          You are more than welcome!