I have painted for years in acrylic and I find that using too much water will fade the colour and at the same time dull your painting. Try using paint

Soak in acetone. When brush is starting to soften gently coax the bristles apart with a pointed object such as a darning needle. Soak again and repeat

Don't wash your brushes in the sink. Acrylic paint clogs the drains. Thanks for your great site. Sheena. (Good point. It's always best to clean excess