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.



20 thoughts on “How To Dispose of Acrylic Paint Rinse Water

  1. 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

      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. 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


      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

    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

      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.

  4. 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 Post author

      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

      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

        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 Post author

          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

    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 Post author

      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

    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 Post author

      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

    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 Post author


      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!


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