How To Dispose of Acrylic Paint Rinse Water

Why You Shouldn’t Pour It Down Drains

Acrylics are a great alternative to traditional oil paint because they are water based, and so there aren’t any fumes, and you can clean up with soap and water. However, at the end of a studio session, the jar or container that you use to rinse off your brushes between colors will have quite a bit of paint in it, and you should not pour this rinse water down drains because many professional-grade paint pigments are toxic, such as the cadmium oxides used for reds, oranges and yellows. Even if you use “non-toxic” student-grade paints, the pigments and acrylic polymers are still problematic for the waste-water treatment processes, and so these shouldn’t go down the drain either.

Disposal As Solid Waste

The solution is to dispose of the material as solid waste. The question is how do you get the water out, which isn’t as simple as just letting it dry out. You may have noticed that rinse water from acrylic paint tends to dry much more slowly than regular water. This is probably due to the acrylic polymers forming an invisible scum on top of the water which acts as a barrier that inhibits evaporation. But there are ways to help the water evaporate faster.

How To Dehydrate Rinse Water

My preferred solution to how to get rinse dehydrated is actually a set of solutions that take advantage of waste energy or ambient energy.  In the winter months, the rinse water can be poured into a metal coffee can or other recycled disposable container and set on a steam radiator. You can also pour it into a disposable aluminum baking pan and sit it by a heater vent or AC vent. In the summer months, there is the floorboard of your hot car with the window cracked open slightly.

I use an old plastic tote that is wide and shallow. This allows the rinse water to spread out and maximizes surface area. I keep the top covered with 1/2″ hardware cloth (wire mesh) to keep out pets and leaves.  If I am painting a lot every day and generating more than my usual amount of  rinse water, I will sometimes put my dehydrator tote next to or under a fan, preferably one that was already running and not turned on just for my rinse water.

Of course, I don’t try to clean out my dehydrator tote between uses. That would be problematic for several reasons (such as the potential to create hazardous dust), so I just have thin layer after thin layer accumulate on the bottom of my dehydrator, which will eventually have to be disposed of and replaced after several years.

Golden Paint’s Recommended Solution

Golden is the leading manufacturer of acrylic paints and mediums, and their website is a tremendous resource of how-to information. They have written a page explaining how to use hydrated lime and aluminum sulfate to quickly precipitate paint solids from rinse water and then filter them out using coffee filters. Keep in mind that hydrated lime and aluminum sulfate are commonly available in the fertilizer aisle of your local hardware store or land and garden center, so we aren’t talking about exotic chemical reagents that you need to special order.

Golden Paint’s Demonstration Video

Golden also has a video on YouTube demonstrating how to use their method to precipitate and filter the solids, but I think the demonstration could be improved. Specifically, they show the reagents being poured from bags, which should be avoided in general because pouring creates so much dust. Instead of pouring, slit the top of the bag completely open and scoop from the bag using an old spoon or scoop or hand shovel. There is another useful point they could have shown, especially since these powdered reagents are likely to be used intermittently and stored for extended periods:

Use Plastic Buckets With Lids To Store Hygroscopic Powders

Powdered reagents that are soluble in water also tend to be hygroscopic (bind moisture from the air) and clump over time. Examples like sugar and table salt come readily to mind, but the problem can be more than a nuisance. For example, old bags of chemical fertilizer are often unusable because the tiny pellets of fertilizer will “sweat” moisture from the air and fuse into one big lump of material that could never be spread in quantities small enough not to kill plants.

The heavy-duty plastic bags that many fertilizers and powdered reagents are sold in weren’t really designed for long-term storage and offer limited protection over time. Often times, twisting the plastic bag closed with a bread ties isn’t enough to seal out the moisture from the air. Sometimes all it takes are a few tiny holes in the bottom of the bag, especially if the material isn’t consumed for months. That is why I save old plastic pails and buckets with lids to store things like grout and thinset, and I would probably recommend them for anyone using lime and aluminum sulfate for precipitating the solids from their paint rinse water. Plastic buckets with snap-on lids are relatively cheap, and you can also get them for free from restaurants, bakeries and house painters.


Scoop from the bag-in-bucket. Cut or fold the bag down as needed.








33 responses to “How To Dispose of Acrylic Paint Rinse Water”

  1. Daniel Hargrove Avatar
    Daniel Hargrove

    I have recently started using acrylic paints, though I avoid cadmium in particular after realizing that using it means visiting a hazardous waste disposal facility. (It is my understanding that hazardous waste is generally burned, thus releasing toxics into the air.)
    I like your guide to disposing of acrylic rinse water. However, for me the guide is problematic. I live in a small apartment with no steam radiator, though I do have central heat. It is not very cold in Houston generally, so the heat doesn’t run often.
    Your suggestion for summertime evaporation is sound, but unfortunately I have no car. Also, there is nowhere outside around my apartment complex where I can leave a container for evaporation. I have no porch or balcony. The apartment management would object to me leaving a container outside my door on the property.
    Perhaps the Golden disposal method would work better for me, I didn’t follow the link. It didn’t look too promising, however.
    Any suggestions?

    1. Joe Moorman Avatar

      Houston is so often humid that dehydration would be difficult outdoors. However, AC dehydrates the air, so you might want to consider a shallow drying pan inside. Thanks,

    2. Gloria H Moore Avatar

      Companies that dispose of hazardous waste by burning them must have scrubbers on their stacks to clean the air. This is EPA required.

  2. Becki Whittington Avatar
    Becki Whittington

    After I let the acrylic paint dry out – then what is done with the solid waste? Toss in the regular garbage or hazardous waste? Thanks.

    1. Joe Moorman Avatar


      After the paint residue dries, it should be stable just like the paint on the canvas. If you wouldn’t dispose of a painting as hazardous waste, then I suppose the paint residue shouldn’t be disposed that way either. It all depends on how much waste you are generating. I try to make sure most of my paint ends up on the canvas, but I routinely walk into studios that make me wonder about the environmental and safety concerns of working as sloppy as some people do.

      All that being said, you could scrape up a lot of paint, and you still wouldn’t have as much heavy metal as there is in one lead weight of the type used to balance automobile rims or one lead fishing weight. Assessing health and safety concerns should always be done in terms of relative risk.


  3. lee Avatar

    just read a method involving sodium carbonate which sounds a bit more simple than golden’s method. have you heard of this one? sodium carbonate can be made from baking soda…apparently

    1. Joe Moorman Avatar

      Sodium Bicarbonate is baking soda, so if that worked, it would be a simple and cheap solution. I haven’t tried it. I’m thinking if that worked, Golden would have recommended it, but you never know.

    2. Jennifer Assinck Avatar
      Jennifer Assinck

      Sodium carbonate is washing soda or soda ash. Washing soda is sold in the laundry detergent aisle.

  4. Dayle Fish Avatar
    Dayle Fish

    I must say finding out I have to go through all of this instead of simply discarding down the drain almost makes decide to dump this not too inexpensive hobby. Why seemingly did this arise? If u run copius amounts of water isn’t that enough? I let my unused paint sit in my pallet overnight and scrap it into the trash I wipe my brush on a rag before dipping into the water to rinse.

    1. Joe Moorman Avatar
      Joe Moorman

      Running extra water won’t change the fact that heavy metals are being added to the waste water stream. It’s pretty easy to pour the water in a plastic dish pan and put it in a hot garage where it can dry out.

    2. Kathy Eaton Avatar
      Kathy Eaton

      I use almost no water in my acrylic pour paintings so clean up is almost waterless. I still generate trash though. Water with acrylic paint will contaminate our planet’s water table and oceans. It doesn’t just clog our drains. That bit of info led me to reducing how much water I use. If I scrap a painting, I scrape the paint into a sealable container to use in future endeavors. I liberally use rags to wipe off tools and wipe out containers. I use wet wipes for cleaning hands and stuff that doesn’t come off by wiping with towels. I lay out the painted towels to dry before the get into the washing machine. One towel goes through many uses before washing. My towels are thin cotton, almost seethru.
      If water IS used, I pour it into a planter container that has gravel at the bottom and is filled with sand. This filters out the paint and let’s the filtered water drain out. Like cleaning a litter box, I can sift out the dried paint to throw away or use a sculpture bases.

      1. Rachelle Avatar

        If you’re throwing your wiping towels in the wash, isn’t that, essentially, doing the same as throwing rinse water down the drain? I’m new to painting and have been trying to get all this sorted out.

        1. Joe Moorman Avatar
          Joe Moorman

          Hi Rachelle,

          That is right. I would never wash rags that had cadmium yellow or red paint on them, and I would be reluctant to stick any paint rags in my washer or dryer. Not only would you be adding pigments to the sewer water, you would risk getting the residue on your clothes. I would hand wash in a bucket while wearing gloves, and then I would let the bucket water dry out to consolidate the pigments.


  5. Barbara Abramowitz Avatar
    Barbara Abramowitz

    I see this thread has been going on a long time, but I just started working with acrylic paints this year. i thought it would be a less messy alternative to working with oils, which I think give nicer effects but require cleanup with turpentine, which I recall with distaste from using it copiously in high school painting.

    Since an art teacher told me not to rinse my reusable palette in the class sink because it would clog the drain I have been thinking about this. Since I have a small apartment with cats and very narrow radiator covering tops, I don’t think leaving paint water, with or without chemicals, sitting atop such is viable. I can try scraping any still moist unused paint into small containers and covering them, but not sure if the paint will stay usable afterwards. Some artists paint their waste paint onto a paintable surface and make abstract paintings with them. I might do that. But the already hardened chips, if scraped off a palette, is there any use to which they can be put? I was half expecting, from the name of this website, to see instructions for making mosaic creations with them. But assuming that saving the chips would just lead to a hoard of…dried paint chips, so we throw them in the solid waste bin instead, the method my art teacher favors (along with the disposable plastic container lids she favors as palettes), isn’t this plastic waste also going to end up somewhere in the earth or sea, making a mess of things?

    I also recently stared using fabric pain pens, which are also mostly acrylic paint, to decorate old stained t- shirts to salvage them. But of course these shirts will be laundered, so now the acrylic paint which I thought was pretty permanently embedded in the fabric, is still getting into the water with every wash?

    I could decorate my shirts with embroidery instead if the paint is a problem.

    I like watercolor painting so I may just go back to that.

    I would appreciate anyone who can give additional advice to what has already been given.

    1. Joe Moorman Avatar
      Joe Moorman

      Hi Barbara,

      Thanks for being aware and concerned about this issue. I would not use acrylic paint on fabrics that will be laundered because the plastic and metal-oxide pigments will erode over time. The best use I have found is to incorporate this waste into canvasses. And not just for abstract paintings. Figurative images can benefit from texture, especially if you want to increase effects where parts of one color brushstroke show through a second color brushstroke.


  6. Rami Chahine Avatar
    Rami Chahine

    Hello Joe,
    So i understand that it is preferable to let the water evaporate instead of using “Golden paints”‘ method ?
    How about the idea somebody posted related to pouring the water into a plant pot with sand and gravel in it? And do you think leaving the dirty water for some time in a container would lead the paint particles to decantate? Perhaps if there’s some soap left in the water?
    Thank you,

    1. Joe Moorman Avatar
      Joe Moorman

      Hi Rami,

      The paint water takes forever to dry because there is a micro layer of plastic on top of the water. A fan or a hot attic is usually required. The Golden Paints method is good, but pouring the water in a plant pot with sand would not make the water dry unless it was leaching out through the porous terracotta, which would soon be plugged with plastic. Whatever method works for you is fine if it prevents the water from being poured down a drain or onto soil. I’ve not experimented with soap or detergent to increase drying time.


  7. Marnie AK Avatar
    Marnie AK

    If the rags or shirts are dried first before putting them into a washing machine, does that prevent anything leaking out of the paint when washed?

    1. Joe Moorman Avatar
      Joe Moorman


      Paint water from brush wiping on rags is different from paint on rags. There isn’t enough paint to dry properly to contain the pigments, and they would easily leach out into the washing machine. I would never contaminate my washing machine that way. Instead, use the rags as much as possible and then dispose of them. Get new rags by cutting up worn out clothing from home or friends. I suspect the ongoing shutdowns and shortages from COVID-19. Will have us all being more frugal and not throwing anything away without considering alternative uses for it. I hope this helps!

  8. em Avatar

    i have a bucket full of acrylic rinse water and it hasnt dried. its been weeks. what do i do?

    1. Joe Moorman Avatar
      Joe Moorman

      Put a fan near it so that the top of the water moves and ripples.

  9. Lindsay Avatar

    I found another website that suggested using cat litter. Fill a container with cat litter, pour in the acrylic paint waste water. The paint residue sits on top and the water is absorbed by the cat litter. Dispose of the cat litter in the garbage. This seems like a more home-friendly version of the Golden method. Any comments?

    1. Joe Moorman Avatar
      Joe Moorman

      The goal is to collect the heavy metals as densely as possible. The cat litter would absorb the metals with the water, and those you would increase the amount of contaminated materials to be disposed of.

  10. Jennifer Assinck Avatar
    Jennifer Assinck

    In my pottery studio, I use a second-hand slow cooker that only works on the low setting. Now that I am painting and having read this article, I now plan to put an aluminum can with acrylic wash water in the slow cooker on low.

  11. Abby Avatar

    I was under the impression that heating up acrylic paint leads to ammonia and formaldehyde being released into the air – would heating up waste water to evaporate not do the same thing?

    1. Joe Moorman Avatar
      Joe Moorman

      Hi Abby,
      I’m sure you are right when there are larger quantities (more than a pint or two), but if you process your waste each day instead of a letting it accumulate, then the water should dry up quickly before any significant quantities could be released.

      Also, I think those outgassing problems are related to heating at a higher temperature or allowing the acrylic to break down over time due to the aqueous chemistry with the metal oxide pigments.

      I’ve never noticed an odor with paint water died out quickly at moderate temperatures, but I’ve definitely noticed scary smells coming from paint water that was allowed to sit around for a day or more.

      Thanks for your great question!

  12. Margery Fain Avatar
    Margery Fain

    For Joe Moorman, thanks for this incredibly insightful blog of comments, questions and answers about the dangers of waste disposal of residual acrylic paint, whether in pure form in a tube, dried on a painting, or diluted with water, or just in small amounts of rinse water from bushes. Just today, I have been doing a tiny experiment with acrylic paints, for the very first time, after rather joyfully but thoughtlessly painting with Water color my whole life. In January, 2022, no one should treat this issue with toxic compounds and the plastic of acrylic, too, as if it doesn’t really matter for the world. So I appreciate the positivity and helpful problem-solving I’ve been reading here. I will continue to follow all your blog, and maybe some better, safer methods with be discussed. I will and try the brush cleaning, over a small tub, and the cat litter method. minimizing entry into any parts of water supply, or sewers which lead to lakes and the ocean, though still landfills. Loved the suggestion that best way to minimize is to use as much of the paint as you can in your paintings, avoiding waste at all steps, and even re-incorporating dried wastes back in to paintings as interesting textures. However, toxic heavy metals and eco-unfriendly plastics still remain just that. So long term, can we eliminate the heavy metals and the toxic acrylic from acrylic paints?? I will now, inspired by this blog, look to see about proper disposal of waste water from water color painting!

  13. Barbara D` Avatar
    Barbara D`

    I am interested in the slow cooker approach. If I were to put a paper towel liner in a glass jar and put the wastewater in that and put the jar in the slow cooker, would that contaminate the slow cooker? If so, any suggestions for preventing that contamination?

    1. Joe Moorman Avatar
      Joe Moorman

      Yes it would contaminate the cooker and it would also produce dangerous fumes. Don’t do that.
      The rule in my house is once something is used for studio or shop, it can’t be used for kitchen.

  14. Sue Avatar

    Could it be safe to pour down the waste acrilic water over the rocks of the train tracks?

    1. Joe Moorman Avatar
      Joe Moorman

      That is based on the idea that the paint isn’t worse than what has already been dumped or leaked onto the tracks by the trains or other dumpers. Probably true, but not the best solution.

  15. Lexie Avatar

    What about cutting a nylon sock and pouring the acrylic waste water through the sock before down the drain? It seems to work to take all the crap out of the water.

    1. Joe Moorman Avatar
      Joe Moorman

      It won’t remove the metal-oxide pigments in the water.

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