Toilet Fill Valve Replacement Cost

Toilet fill valve replacement cost in 2026 runs $15 to $35 for the part alone, or $140 to $250 with professional installation. The fill valve, also called a ballcock, is the tall valve on the left side of the toilet tank that refills the tank after every flush and shuts the water off at the correct level. When it fails, the toilet fills slowly, runs constantly, hisses, or refuses to fill at all. Replacing it is a straightforward job that takes 30 to 60 minutes, and many homeowners can do it themselves with basic tools. This guide covers the cost, the warning signs, how to pick the right valve, and the exact steps to replace it.

Average Fill Valve Replacement Cost in 2026

As with other tank parts, professional cost is mostly the service call fee. Bundling a fill valve with a flapper replacement in one visit is smart if both parts are aging, since the labor overlaps almost entirely. For broader pricing, see our toilet repair cost guide and the toilets hub.

What Is a Toilet Fill Valve?

The fill valve sits on the left side of the tank (as you face the toilet) and connects to the water supply line coming through the bottom or side of the tank. After a flush, the falling water level drops the valve float, which opens the valve and lets fresh water flow into the tank and, through a small refill tube, into the overflow tube to refill the bowl. When the water reaches the set level, the float rises and shuts the valve off. That is the entire cycle, repeated thousands of times over the valve's life.

Older toilets used a ballcock with a large floating ball on an arm. Modern toilets use a compact tower-style valve with a float cup that slides up and down the valve body. The most common replacement valve in the US is the Fluidmaster 400A, a universal tower valve that fits most toilets and costs $15 to $25. Other major brands include Korky, Kohler, and Toto, with brand-specific valves for certain models. The differences are mostly in height adjustment, noise level, and refill rate.

Fill valves are height-adjustable, which matters because tank heights vary. A universal valve adjusts from about 9 inches to 14 inches tall. Before buying, measure your tank height from the bottom of the tank to the top of the overflow tube, and buy a valve that covers that range. A valve that is too tall will not fit under the tank lid; a valve that is too short cannot reach the correct water level.

Signs Your Fill Valve Is Failing

• Slow filling: the tank takes several minutes to refill, or fills noticeably slower than it used to. Mineral buildup or a failing seal is often the cause.
• Running constantly: the valve never fully shuts off, so water trickles into the overflow tube indefinitely. This wastes water and wears the valve further.
• Hissing, groaning, or foghorn sounds: a worn valve diaphragm vibrates as water passes through, producing hissing or a loud groaning noise during and after filling.
• Toilet will not fill: the valve is stuck closed, the float is jammed, or the supply line is blocked. Check that the wall shutoff valve is fully open first.
• Water level too high or too low: a float that no longer adjusts correctly leaves the water level wrong, causing weak flushes or constant overflow.
• Ghost flushing combined with running: a fill valve problem can mimic a flapper problem. If the flapper is new and the toilet still runs, suspect the fill valve.

Before replacing the valve, try two quick checks. First, make sure the wall shutoff valve is fully open; a partially closed valve causes slow filling that looks like a valve failure. Second, check for sediment: turn off the water, remove the valve cap if your model allows it, and flush out any grit. On some valves, cleaning the seal restores normal function and buys months of extra life. If cleaning does not help, replacement is the right move.

How to Choose the Right Fill Valve

For most toilets, a universal tower valve like the Fluidmaster 400A or Korky QuietFILL is the correct choice. They fit 2-piece and most 1-piece toilets, adjust to common tank heights, and include a refill tube and clip. Quiet-fill models cost a few dollars more and reduce the hissing and gurgling sounds during refill, which is worth it in a bathroom near a bedroom.

Brand-specific valves are needed for certain models. Kohler toilets with a canister flush system, Toto toilets with proprietary valves, and some one-piece designer models use valves that are not interchangeable with universal parts. Check your toilet brand and model number, stamped inside the tank or on the underside of the lid, before buying. When in doubt, photograph the existing valve and show it to a plumbing supply store or search the model number online.

Also consider the refill rate. A valve with an adjustable refill tube lets you balance bowl refill against tank refill. Too little bowl refill causes a weak flush and a low bowl water level; too much wastes water down the overflow. The refill tube should clip into the top of the overflow tube, not dangle into it, and should sit slightly above the water level to prevent back-siphoning.

DIY Fill Valve Replacement Steps

Replacing a fill valve takes 30 to 60 minutes and requires adjustable pliers, a sponge, a towel, and possibly a small bucket. Here is the process:

1. Turn off the water: turn the wall shutoff valve clockwise until it stops. If it is stuck or dripping, stop and call a plumber.
2. Empty the tank: flush to drain the tank, then sponge out the remaining water. Hold a towel under the supply connection to catch drips.
3. Disconnect the supply line: unscrew the supply hose from the bottom of the old fill valve. Have the towel ready; some water will spill.
4. Remove the old valve: unscrew the locknut under the tank that holds the valve in place, then lift the old valve out of the tank.
5. Set the new valve height: adjust the new valve so its critical level mark sits about one inch above the top of the overflow tube. Follow the instructions in the box for your specific model.
6. Install the new valve: insert it through the tank hole, thread on the locknut underneath, and tighten by hand plus a quarter turn with pliers. Do not overtighten, which can crack the porcelain.
7. Reconnect the supply line: attach the supply hose to the new valve and tighten snugly. If the supply hose is old, stiff, or corroded, replace it now for $10 to $25 rather than reusing it.
8. Attach the refill tube: clip the refill tube into the top of the overflow tube so it directs water into the overflow during refill.
9. Turn the water on slowly: open the shutoff valve gradually, check all connections for leaks, and let the tank fill.
10. Test and adjust: flush several times, check the water level, and adjust the float so the water stops about one inch below the top of the overflow tube.

Leaks at the tank connection are the most common DIY mistake, and they are almost always caused by overtightening or by a worn washer. If the connection drips, turn off the water, check the washer, and retighten gently. If the tank itself is cracked around the valve hole, stop and call a plumber: a cracked tank means the toilet needs replacing, not a new valve.

Adjusting the Water Level Correctly

Correct water level is essential to a good flush and to water savings. The water should stop about one inch below the top of the overflow tube. If the level is too high, water flows constantly into the overflow tube and is wasted. If the level is too low, the flush is weak and the bowl may not refill properly.

On tower valves, adjust the level by turning a screw on top of the valve or by sliding the float cup up or down and locking it in place. Make small adjustments, flush, and recheck. The refill tube also matters: it should deliver enough water to the bowl so the bowl level returns to normal after a flush. If the bowl level is low after flushing even though the tank level is correct, the refill tube may be mispositioned or pinched.

While you are adjusting, check the flapper too. A fill valve replacement is an ideal time to inspect the flapper, since both parts age on a similar schedule. If the flapper is warped or stiff, replace it at the same time for $5 to $20 and save a future visit. See our toilet flapper replacement cost guide for that job.

Professional Replacement: What to Expect

A plumber replacing a fill valve will shut off the water, drain the tank, remove the old valve, install and adjust the new valve, reconnect the supply line, test the flush several times, and check for leaks, all in 30 to 60 minutes. Cost is $140 to $250, including the part and the service call fee. A good plumber will also inspect the flapper, the flush valve, and the supply line, and will recommend replacing the supply hose if it is old, since a burst supply hose is one of the most damaging home floods.

Professional replacement is the right call if the shutoff valve is stuck, the supply line is corroded, the toilet is a brand-specific model you are unsure about, or the tank has any sign of cracking. It is also sensible to bundle the job with other repairs: a flapper, a supply hose, and a fill valve in one visit cost far less than three separate visits. For a full picture of toilet repair pricing, see our toilet repair cost guide.

Fill Valve Maintenance and Lifespan

A quality fill valve lasts 5 to 10 years in most homes. Hard water shortens that life, because mineral deposits build up on the seals and moving parts. In hard-water areas, consider a water softener or at least periodic descaling: turning off the water and flushing the valve with vinegar can remove light buildup and extend its life. In-tank cleaning tablets also damage fill valve seals, just as they damage flappers, so keep chemicals out of the tank.

• Listen for changes: new hissing, groaning, or slow filling is an early warning. Investigate before it becomes a constant run.
• Check the water level yearly: a level that creeps up over time suggests a wearing float or seal.
• Replace the supply hose with the valve: a $10 to $25 braided stainless hose is cheap insurance against a burst.
• Keep the model number handy: tape your toilet brand, model, and valve type inside the tank lid for the next replacement.
• Fix running toilets promptly: a running toilet wastes 200 gallons or more per day and inflates the water bill fast.

A fill valve replacement is a small job with an outsized payoff: a quiet, efficient toilet that fills correctly and stops wasting water. For help with a fill valve, a flapper, or any toilet repair, call (877) 762-1902.