How to Fix a Slow Filling Toilet
Plumbing Q & A - Ask the Plumber
Question- "My toilet fills very slowly and the inners and valve have been replaced. What should I do?"
Answer-In our opinion, we recommend that you check the water pressure going into the valve. If the pressure is good at the valve then change the fill valve again however if the pressure is not good there then you have a blockage in the cold water line.