How to Fix a Slow-Filling Toilet

If you've tried the water supply and that isn't the issue, try cleaning the pump and valve. Sediment can build up over time, and a good cleaning may fix the issue.

If the exterior of the fill valve has mineral buildup on it, use vinegar and a toothbrush to clean off the sediment. Once it breaks off, wash the valve with warm water and soap. Then rinse it off.

Next, disassemble and clean the fill valve and float cup. Turn the water off. Remove the valve top and cover the opening with an inverted cup. Hold the cup over the opening and turn the water supply back on to clear the debris.

Check to see what type of assembly you have. If you have an older-style ball cock assembly (as shown in the image), try installing a new fill valve and float cup assembly.

If you've checked the shut-off valve and cleaned the assembly and nothing seems to be working, then this may be a plumbing issue. Try this test:

If the supply line to your toilet is flexible, shut off the water and disconnect it at the toilet side. Run the line into a bucket. If the pressure coming from the shut-off valve is low, you may have a blockage in your water pipe. Unless you have experience working with pipes, it's best to call a plumber.

If you've cleaned everything and a plumber can't fix it, then it's probably time to purchase and install a new toilet.

Toilet Buying Guide
How to Install a Toilet
Watch our DIY Basics video: How Do I Unclog My Toilet?