How (and Why) to Filter Your Paint Water

In this tutorial I’m going to show you how you can make a water filter from recycled packaging and charcoal. I started thinking about this project a while ago at the suggestion of a friend and fellow artist who was concerned about pouring pigment and paint particles that could be toxic to marine life down the sink, especially from acrylic paint, which is made from plastic.

I want to point out upfront that while this is an absolutely valid concern, and we should all be doing what we can to minimise our imprint on our environment, it’s a small number of very big businesses who are responsible for the lion’s share of environmental pollution. I’ll be reusing a piece of plastic waste from one of those companies in this project. These companies spend a lot of money on PR to try and shift blame for their environmental impacts onto us as individuals, but even while we do what we can to help improve things, it’s these big companies that need to step up, take responsibility and change their processes.

Back to filtering water though, if you’re an artist working from home or in a small studio without easy access to water, this could be a good trick for you. If you own your own home or studio and are able to install a filter under your sink, that’s a great step to take. If you’re like me and can’t change your plumbing easily, you can make this simple filter.

When I made my first filter, it was to stop pouring potentially toxic particles down my sink, but what I actually really love is not needing to constantly be carrying jars of water up and down stairs around my house; I can just reuse the same water over and over again for as long as possible. Eventually the filter will reach a point where it stops working, and you’ll need to dispose of the charcoal safely and replace it with a fresh batch.

Activated charcoal (mine is the kind used in aquariums)

Jar/pestle or something to crush up the charcoal if you need to

Recycled plastic bottle

Recycled cloth bag

Water

Utility knife

Begin by crushing up some activated charcoal (I bought the kind used to help filter water in aquariums) in a jar or container with a pestle or similar tool.

I crushed up my charcoal in batches and transferred it to a cheesecloth bag as I went, until I had enough charcoal in the bag,

When your charcoal is ready, soak your bag in some water while you prepare your bottle.

Cut an empty recycled plastic bottle in half carefully with a utility knife, then invert the top so that it's resting inside the bottom half.

After running my water through the filter once, I noticed that it was letting the water through too fast and washing out a lot of the charcoal dust, so I cut a small notch in the bottle cap and screwed it back onto the bottle. This helps slow down the water so that the charcoal can filter it properly.

Place your soaked bag of charcoal into the bottle, with the knotted end of the bag closest to the cap. The extra material bunched up here will help the water drip through more slowly.

Pour your dirty watercolour, gouache or acrylic paint water through the filter! You can now tip this water safely down the sink or keep using it to clean your paint brushes