Fill Valve — toilet tank valve that controls refilling

A fill valve is a toilet tank refill valve that refills the toilet tank and bowl after each flush and shuts off at the set level.

Fill Valve diagram — labeled parts, dimensions, and installation context

What It Is

A fill valve is the assembly inside a toilet tank that controls refilling after a flush. As the water drops, the float opens the valve, and as the tank fills again, the float shuts it off.

Types

Older toilets may use ballcock-style assemblies, while most replacements are modern float-cup fill valves. Adjustable-height models fit different tank depths more easily.

Where It Is Used

Fill valves are used in residential gravity-flush toilets and many commercial tank-type toilets. They work with the flush valve but perform a separate refill job.

How to Identify One

Remove the tank lid and look for the tall plastic assembly connected to the supply line. A float cup sliding on the shaft is the easiest clue.

Replacement

Replace the fill valve when the toilet runs constantly, refills slowly, makes loud noises, or cannot shut off at the correct water level. It is one of the most common toilet repairs.

Fill Valve — FAQ

What does a fill valve do?

It refills the toilet tank and bowl after each flush and shuts off at the set level. In a home, that helps the surrounding system work the way it should.

How can I tell if a fill valve needs attention?

Continuous running, hissing, slow refill, and water rising into the overflow tube are common clues. Mineral buildup and worn seals inside the valve often cause the problem.

Can I replace a fill valve myself?

Yes, this is one of the more accessible plumbing repairs for homeowners. Turn off the toilet supply, match the new valve height, and reconnect the refill tube correctly.

How much does fill valve repair or replacement cost?

The part is usually inexpensive, so DIY replacement stays low cost. Hiring it out is still modest compared with most other plumbing repairs.