To repair a toilet fill valve, shut off the water at the wall, flush to empty the tank, then either clean and adjust the valve or replace it with a new one. Most replacement valves fit in a few minutes with hand tools. If your toilet runs after flushing, hisses between flushes or fills very slowly, the fill valve is a prime suspect. Start with our toilet repair overview if you are not sure which part is failing.
A fill valve is a float-operated valve that lets water into the tank and closes when the level is right. Wikipedia's flush toilet article notes that on older models it is called a ballcock.
How do you know the fill valve is the problem?
The fill valve is the problem when water keeps flowing into the tank after it reaches the right level, so it spills into the overflow tube, or when the tank takes a long time to refill. A hissing sound after the tank is full is the classic sign.
Tell it apart from a leaking flapper with a simple check. Lift the tank lid and look at the water level. If the water is running into the overflow tube, it is the fill valve or its float setting. If the water level is fine but the tank refills every few minutes with no one flushing, the flapper is leaking and the fill valve is only doing its job. Put a few drops of food coloring in the tank and wait about 10 minutes without flushing. Color in the bowl means a flapper leak, as described by EPA WaterSense. Our flapper repair page covers that.
Other signs of a failing fill valve:
- A whistling or banging noise as the tank fills. Banging may be water hammer, not only the valve.
- A tank that fills only partly, so the flush is weak.
- A float cup that sticks, or a float ball that has water inside it.
How do you adjust a toilet fill valve before replacing it?
Set the water level about one inch below the top of the overflow tube, or at the fill line marked on the tank if there is one. Most valves have an adjustment screw or a clip on the float. Turning it lowers or raises the shutoff point. A level set too high is a common reason for constant running.
Steps:
- Remove the tank lid. Find where the water stops.
- On a float cup valve, pinch the clip and slide the cup down, or turn the screw counter-clockwise, to lower the level. On an old ballcock, gently bend the float arm.
- Flush and let the tank refill. Check again. A full turn of the screw typically moves the level about half an inch, so go in small steps.
- Check the little refill tube that runs from the valve to the overflow tube. It should clip to the top of the overflow tube with its end above the water line. If it is pushed below the water, it can siphon water into the bowl.
If the valve still does not shut off after the level is right, replace it.
How do you replace a toilet fill valve?
Replace a toilet fill valve by closing the shut off valve, emptying the tank, disconnecting the supply line, removing the old valve's locknut, and dropping a new one in. Match its height to the tank, tighten the nut by hand and a bit more, reconnect the line, and adjust the water level. Allow about 30 minutes the first time.
The long version:
- Shut off the water at the valve behind the toilet and flush. Sponge out what remains. If the valve will not close, see toilet shut off valve repair.
- Disconnect the supply line from the bottom of the tank with a wrench, with a towel under it.
- Remove the locknut that holds the old valve under the tank, then lift the valve out.
- Set the new valve's height to match the manufacturer's instructions, usually so that the critical level mark sits an inch or so above the top of the overflow tube. Adjust the shank before you install it.
- Tighten the new locknut hand tight, then a quarter turn more. Over-tightening cracks porcelain tanks.
- Reconnect the supply line, clip the refill tube, open the water and watch for drips.
Take the old valve to the store if you are unsure about the fit. Universal replacement valves are sold in most hardware stores for roughly $10 to $40, per published cost guides. If the tank bolts or the rubber washers at the tank and bowl joint are also leaking, do the repair of those at the same time. That is the toilet flapper gasket replacement mentioned in some searches: the flapper seals the flush valve opening, and the thick rubber gasket at the tank to bowl joint is a separate part that fails slowly and leaks at the base of the tank.
Can a running toilet make your water bill high?
Yes. A running toilet can add a lot to a water bill because it wastes water all day without anyone noticing. EPA WaterSense says a leaking toilet can waste about 200 gallons a day, and a constantly running fill valve can pass 0.5 to 3 gallons per minute.
That is not a typical day. A small flapper leak wastes less, and a fill valve stuck wide open wastes far more. A quick way to check: read your water meter before bed, and again after a few hours of no water use. If the dial moved, something is leaking, and the toilet is the first place to look. We explain more on why your water bill is so high.
Do not wait. A toilet that runs day and night costs more in water than the parts do.
What if the toilet supply line bursts?
A burst toilet supply line floods the bathroom fast, so close the shut off valve behind the toilet at once. If it will not turn, close the main shut off for the house, then mop up and call a plumber. Do not wait to see if it stops.
A supply line is the flexible hose or tube between the shut off valve and the fill valve. Old plastic or thin braided lines can split at the fitting. Check yours: if the braided line looks rusty, kinked or has a green crust at the nuts, replace it now. For active flooding or water near outlets, switch off the breaker to that room only if you can reach it safely and dry. Then see what to do in a plumbing emergency. If you suspect a pipe inside the wall, our guide on how to know if a pipe burst helps.
What does it cost to repair a toilet fill valve?
A plumber typically charges about $60 to $200 to replace a toilet fill valve, with most published guides landing between $100 and $200. A fill valve and flapper together are often $150 to $225. The part costs $10 to $40, so most of the price is the service call and labor.
Angi puts toilet repair in Los Angeles at an average of about $290, with a range of $151 to $429. A single fill valve usually lands below that average, since it is a small job, but a slow-moving or hard-to-reach valve costs more. The labor cost to replace a fill valve is mostly the first 30 minutes or hour of the visit, so ask about a flat price. Because plumber visits include a service call, it is better to bundle the valve, flapper and supply line into one visit than to pay twice.
For a price that fits your house, use the quote page. We'll arrange a local plumber, and you get a written quote before any work starts. For a look at the bigger picture, see City of Angels Plumbing.
Common questions
Should I call a plumber to fix a toilet fill valve?
You can fix it yourself if you are comfortable with a wrench and a bucket. Call a plumber if the shut off valve is stuck, the supply line is corroded, the tank is cracked, or the toilet still runs after you replace the valve. A plumber also saves time if you have several toilets to do.
How long does toilet fill valve repair take?
Adjusting the water level takes minutes. Replacing the valve is usually a short job for a plumber once the water is off. The part that takes time is a stuck shut off valve or a corroded supply line, so ask the plumber what they see when they arrive.
What should I ask before I hire someone to replace a toilet fill valve?
Ask whether the quote includes the part, the supply line and the service call. Ask whether replacing the flapper at the same time costs extra, since the two wear out together. Ask for their CSLB license number if the job is likely to run past $1,000 or needs a permit.
Does someone need to be at the property?
Yes, or someone should give the plumber access to the bathroom and the water shut off. The water to that toilet will be off for a short time, and it helps to confirm the fix yourself by flushing once the job is done.
Why does my toilet fill valve make a noise?
A hissing sound means water is passing a worn seal. A whistling or squealing sound often points to a worn valve. Banging can be water hammer in the pipes. Replacing the fill valve often fixes the first two. If banging continues after, a plumber should look at the supply side.