Acrylic paint should not be poured down the sink. The reason is that acrylic is essentially a plastic paint, and it would certainly not be advised to put any plastics down the drain. Every time acrylic paints are rinsed small particles of plastic get in the water, creating an acrylic sludge over time. This accumulation of acrylic sludge can clog a drain, and more importantly is very bad for the environment. Those wondering how to throw away acrylic paint should know the best option is to let the paint air dry until it solidifies then toss it out in the regular trash.