I've just realized that watercolours with a water brush are the artsy-painty thing that uses less water among all of the ones that I have around the house.

With just a few squeezes and passes on a wiping cloth for washing the brushes, and no other tool that requires washing, it's pretty hard to beat them.

Given the name, that's somewhat counterintuitive, however :)

(yes, I could be using pencils, pastels, pens and a lot of other things that don't require washing at all)