How to Dispose of Water-based Paint Water?

Water-based paints are any water-soluble paint whose uses range from painting walls, wood, and canvases. There are two types of water-based paints, acrylic, and latex-based paint. Both of these paints contain less volatile organic compounds than oil-based paints. This is why they have gained popularity in recent years since most municipalities passed new regulations against volatile organic compounds. 

There are certain advantages to using water-based paints over oil-based paints. However, the wash-water from water-based paint is not good for the environment and should not be poured down the drain, or the stormwater drain. There are chemicals in these paints that can be very harmful to the environment. Moreover, these paints can clump together and clog pipes. This article will explain how to properly dispose of paint water and what can be the issue with dumping the water right down the drain.  Lastly, it will describe the problems with not disposing of paint water properly. 

How to Dispose of Water-based Paint Water?

There are several ways you can dispose of paint water. One way is to wait to leave the water sitting outdoors or in your garage. Wait until the water evaporates or the paint deposits at the bottom. If there is little water, the water will dry out relatively quickly. 

Once the water dries out, you have two options. If the paint at the bottom is of sludge consistency then you can mix it with cat litter to dry it out and create solid clumps. These clumps can then be thrown into the garbage. Another option is to wait until the paint dries out completely. Then you can scrape the paint off the bottom of the container and throw it out into the garbage. 

If there is too much water, you can wait for the paint to deposit at the bottom and then slowly take the clear water off the top and pour it down the drain. You can then treat the sludge at the bottom with cat litter as before. 

Allowing water to sit until it evaporates or the solid parts precipitate is a lengthy process. In humid climates this may take far too long or may not happen at all.

If you do not want to wait that long then there are easier, more time-saving techniques you can apply. 

One such process involves adding aluminum sulfate and powdered lime respectively into the paint water to make all the pigments clump together. You add a small amount of aluminum sulfate and then some lime, then you wait for the paint to precipitate to the bottom. 

Once the paint has precipitated to the bottom, you need to use litmus paper to check the pH of the water. If the pH is between 5-9, then we can assume the reaction is successful. If the pH is still too low, repeat the process. 

Then the pigments are filtered out by a coffee filter paper, and the water can be safely poured down the kitchen drain. You can check the details of the protocol here.

The above methods only work if there aren’t any heavy metals like cobalt and cadmium in the paint. Some paints still contain lead, even after lead in paint is banned in most countries. Pay careful attention to the packaging. If the paint contains toxic chemicals, then the above methods cannot be tried. If there is lead, cobalt, or cadmium in your paint water, call your local hazardous waste management facility and find out how to deal with that water. 

The problem with pouring paint water down the municipal sewer: 


The painted water can contain heavy metals. These metals are very hard to remove from wastewater. This means, after the wastewater is treated and released into local waterways, it can cause toxicity to aquatic life. These metals accumulate in the systems of fish and other animals that live on fish.

This means these metals like cobalt, cadmium, and lead can eventually end up in our systems and cause severe neurological and developmental issues. 

Even if the paint water is free of harmful metals, it can still be an issue for our pipes. These paints clump together and can block pipes. Blocked pipes are extremely expensive to replace and can be difficult to clean up as well. 

The problem with pouring paint water into the stormwater drains: 

Keep in mind that the drains on the sides of the streets that are used to remove rainwater from the roads do not connect to the municipal sewer system. Instead, these stormwater drains link to a local water source like a lake or a pond directly. 

Pouring paint water down these drains is not allowed. The painted water can cause the turbidity of the water at the source to increase. The paint forms clumps and turns sludgy which can make the water at the source more turbid. This is bad for aquatic life and vegetation.

Turbid water will allow less sunlight to pass into the water, which may cause the aquatic plants to start dying off, cutting off the food supply for many aquatic animals. The entire aquatic ecosystem can become severely imbalanced this way, causing the fish population to start dwindling. 

The best thing to do when taking up a painting project is to minimize the use of water as much as possible, this will leave less waste for you to dispose of later on. 

Paint water may sound like an innocent enough waste but it can cause trouble for our pipings, aquatic life, and even our health if it is not disposed of properly. 

Conclusion: 

There are certain advantages to using water-based paints over oil-based paints. However, the wash-water from water-based paint is not good for the environment and should not be poured down the drain, or the stormwater drain. There are chemicals in these paints that can be very harmful to the environment. Moreover, these paints can clump together and clog pipes. This article explains how to properly dispose of paint water and what can be the issue with dumping the water right down the drain. Lastly, it describes the problems with not disposing of paint water properly. 

Frequently Asked Questions (FAQs): How to dispose of water-based Paint Water

 Can you pour water-based paint down the drain? 

No, it can cause the pipes to clog and may contain heavy metals that harm the aquatic ecosystem. 

Can you pour water-based paint water down the drain? 

No, it can also cause the pipes to clog over time and may contain heavy metals that are harmful to the environment. 

Can I pour water-based paint water onto the grass? 

No, if the paint had heavy metals, it’ll affect the soil ecosystem and can potentially leak into the groundwater. If the paint is non-toxic, it’s not going to be a big issue, but it’s a bad practice since the paint water can get washed away by rain into the storm drains. 

Can I pour paint water down the storm drains? 

The storm drains are there only to remove rainwater from the streets. It connects directly to a local water source where the rainwater is channeled into. The water is not treated. Washing paint water with all the solids in it, as well as potentially toxic metals, will harm the ecosystem of the water source. 

Can I dump paint water outside? 

No, it is not safe to dump paint water outside. 

Is water-based paint safe?  

Most newer formulations are much safer than many solvent-based paints. However, it is not 100% safe, and paint water needs to be handled according to protocol. 

References: 

  1. Kessler, D. (2022). How to Dispose of Acrylic Paint Water-David M. Kessler Fine Art. Retrieved 6 February 2022, from https://www.davidmkessler.com/blog/2020/2/26/how-to-dispose-of-acrylic-paint-water
  2. (2022). Retrieved 6 February 2022, from https://www.ehow.com/how_7815665_dispose-paint-water.html
  3. How to Recycle/Dispose of Paint – Latex / Water-Based | Waste Authority of Jackson County. (2022). Retrieved 6 February 2022, from https://www.wasteauthority.org/site/how-to-recycledispose-of-paint-latex-water-based/
  4. Disposing Paint Waste. (2022). Retrieved 6 February 2022, from https://ecopainting.ca/eco-painting/environmental-tips/disposing-paint-waste/
  5. Paint Disposal Guide — the Green Project. (2022). Retrieved 6 February 2022, from https://www.thegreenproject.org/paint-disposal
  6. Water-based paint. (2022). Retrieved 6 February 2022, from https://www.oregonmetro.gov/tools-living/healthy-home/common-hazardous-products/paint-water-based
  7. Water-based Paint Disposal. (2022). Retrieved 6 February 2022, from https://www.artistsnetwork.com/magazine/water-based-paint-disposal/
  8. Water-Based Latex Paint | Cherry Hill Township, NJ. (2022). Retrieved 6 February 2022, from https://www.chnj.gov/610/Disposal-of-Water-Based-Latex-Paint
  9. Acrylic Water Paints. (2022). Retrieved 6 February 2022, from https://www.protekpaint.com/acrylic-paint-water-based-latex/
  10. Should You Clean Paint Brushes in Your Kitchen Sink?. (2022). Retrieved 6 February 2022, from https://painterdoug.com/clean-paint-brushes-in-sink/


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