As much as 80,000 gallons of water can be wasted each year by an undetected toilet tank leak, so it’s important to occasionally check the toilets around your home. Parts of your toilet may need to be fixed or replaced over time and these are often repairs you can do yourself, or with the help of some plumbing services should you find yourself in need of assistance.

Here is a step by step guide to toilet repair. However, sometimes there can be unexpected issues that you may run into when trying to repair an issue. Hopefully, the below tips should be helpful in guiding you through the whole process, but you can always visit our Plumbing Department for additional assistance and we would be happy to answer your questions.

See this illustration for the working parts of: (a) old-style ballcock/flush valve toilet tank and (b) the modern tank with plastic valves.

toilet repair diagram

Tools & Materials Needs For Toilet Repairs

  • Adjustable Wrench
  • Pipe Wrench
  • Channel-Locking Pliers
  • Pliers
  • Locking Plier/Wrench
  • Refill Valve
  • Ballcock Parts
  • Flapper
  • Riser Tube
  • Flush Valve
  • Flush Ball
  • Float
  • Penetrating Oil
  • Masking Tape
  • Wiping Cloths
  • Sponge
  • Hacksaw
  • Hand Cleaner

1) Check For Leaks

Most toilet flush tanks work in the same way. The toilet tank contains two valves- a flush valve and a refill valve. One type of refill valve is commonly called a ballcock.

When the flush valve fails to seat properly, water is leaked from the tank into the bowl. The leaked tank water is replenished by the refill valve, causing a continuous flow of wasted water.
check for toilet leaks

If the refill valve leaks, the tank overfills and the excess water runs from the overflow pipe into the toilet bowl. A waterlogged float causes overflowing, even if the refill valve itself is functioning properly.

You can check for a leaky flush valve very simply, as shown in this image. Shut off the water supply to the toilet. The shutoff valve is located beneath the tank on the left side as you face the toilet. Mark the water level, then check it again in 20 minutes. If the water level has fallen below your mark, the flush valve is leaking. If not, the flush valve did not leak, and you know that any leaks are being caused by the refill valve.

To check both the flush valve and the refill valve for leaking, simply drop some food coloring or laundry bluing into the toilet tank to color the tank. Do this when the tank is fully refilled after a flush. Don’t flush the tank again until you have inspected the toilet bowl a few minutes later for signs of color. If the bowl water has a hue, there’s a leak.

2) Simple Adjustments

Your toilet tank may simply need a good “tune-up.”

Refill Valve
If your tank has a conventional ballcock valve, the water level is adjusted by bending the float arm.
adjust refill valve

The level should be high enough for complete flushes, but the water should not be to the top of the overflow pipe. Your tank should have a colored or molded water level mark. It should never be set so low that the bowl does not refill with the trap sealing water. The rule of thumb is to set the water level about ” below the top of the overflow pipe.

If the float rubs on other parts, simply adjust the float arm sideways. If the float lacks buoyancy, unscrew then shake it to determine if it is waterlogged. A waterlogged float should be replaced. The float arm can also be replaced if needed. If you are attempting all these by yourself, you might need to have an array of tools that can help you in such projects. That does not mean you have to buy a brand-new fancy toolbox. Instead, you can look up local classifieds to see that used snap on tool box you wanted for your DIY projects. Items listed on such portals tend to be considerably cheap so that you won’t have to break your bank for it.

Coming back, in tanks, using modern plastic refill valves, the tank water level is adjusted in other ways. If your tank uses a hand nut, turn the nut clockwise to raise, or counterclockwise to lower, the water level. Or your tank may have a sliding pinch clamp on an adjustment rod.
inspect float

Flush Valve
Replacements for a flush valve (you might want to check out Versa Valves and similar companies for the same) and its actuating mechanisms are available, but it may be possible to stop a leak with minor adjustments. Check the following mechanisms before purchasing replacements.

See that guide arm is centered directly over the seat. The guide arm should drop the flush ball directly into its seat. If the flush ball is not seating properly, make the adjustment shown in the image.
inspect flush valve

The guide arm should allow the flush ball to rise enough for a complete flush. If not, raise the arm. Be careful that it isn’t too high- then it will prevent the ball from closing completely.

Check that the upper lift wire pulls the flush ball high enough. To adjust it, simply bend the wire for a higher or lower lift.

The lifting hardware on a flapper-type flush valve should raise the rubber flapper to start a flush, but should not hold the flapper up off its seal. If this is occurring, the hardware is adjusted too short. Some types allow you to slide the flapper itself up or down on the refill tube to ensure the flapper meets the valve seat squarely. The lifting hardware and flapper height adjustments are the first things to check when flapper problems arise.

Refill Tube
If the bowl-refill tube is out of place, water is routed directly into the tank, rather than replenishing water in the bowl. When this is the case, you will likely hear splashing sounds during tank refill. The refill tube should aim directly into the overflow pipe but should not reach below water level. If the tube extends too low, it will siphon tank water silently away. Fix it by repositioning as shown.
reposition refill tube

Defective refill tubes on some valves can be replaced with new plastic ones. Simply place one end of the plastic tube over the serrated plastic lug on the body of the valve and place the plastic holder in the top of the overflow pipe.

3) Fixing The Flush Valve

Most toilet tank troubles can be traced to a faulty flush valve. You can either 1) Repair the old flush valve, 2) Replace the flush ball with a modern flapper or install a glued-in replacement flapper, or 3) Install a new flush valve.

Examine the old flush ball or flapper. If it is aged or encrusted with deposits, replace it with a new one. Scale deposits on the seat can be removed with steel wool (see image) or with a No. 500 wet-or-dry abrasive paper. But if the valve still leaks, it must be replaced.
repairing flush valve

You can install a new guide arm if necessary. To remove the lift wire from a flush ball, turn it counterclockwise with pliers. If you are replacing all parts, simply cut off the old lift wire.

To replace a flapper, disconnect the lift hardware from the trip arm and slide the flapper up and off the overflow pipe. See image.
replace flapper

Install the new unit, reversing directions and connect the lift hardware back to the trip arm. Any excess lift chain can be cut off or left dangling, if it doesn’t interfere with toilet operation.

A loose trip handle can be fixed by tightening. The nut has left-hand threads and must be turned counterclockwise to tighten (looking from inside the tank). Or you can install a replacement trip handle.

Glue-In Repair Kit
Many replacement flush valves simply glue in place on top of the old valve seat. While several brands are available, not every type of flush can be replaced by these devices. See image.
glue-in repair kit

On single-piece toilet tanks-with a flush valve held in place with flanges that fit inside the opening- the flapper-ball may bind and prevent a leak-proof seal. On more common two-piece toilets, this problem does not occur.

Using a glue-in repair kit is quick and easy, but you must follow the manufacturer’s instructions. To be sure you purchase the right kind of repair kit, take a rough drawing or photo of the bottom of your toilet tank and flush valve to the store.

4) Installing A New Flush Valve

Flush valves are held to the tank by one large jam nut on the bottom of the tank. Installing a new flush valve usually requires removing the toilet tank from the bowl, which can be complicated. Although wall-mounted tanks may not need to be removed. Still, since the procedure can be slightly tricky, availing Boston plumbing services (if that is where you live) might be the right way to go. Having a professional do the work for you might decrease the chances of the problem occurring again lower.

In some cases, the toilet tank must be removed, for which you need to turn the water off completely, flush the toilet and hold the trip lever down to evacuate most of the tank water. Use a sponge to remove the remaining water. Disconnect the tank’s inlet fitting from the water supply. If the flexible riser tube is damaged, replace it.

Then unscrew the two rubber-gasketed bolts flanking the flush valve. These bolts go through the tank and bowl flange, with nuts underneath. Use caution- forcing the bolts may cause you to break the bowl, tank, or both. Use plenty of penetrating oil on the threads. If they still won’t budget without force, try wrapping masking tape around a hacksaw blade and sawing with the teeth facing you, so the blade cuts on the “pull” stroke. The layer of masking tape will protect the bowl’s glazed surface from saw scratches.

The tank should now lift away from the bowl. Lay it upside-down on a throw rug or newspaper padding to protect it, and unscrew the large nut holding the flush valve to the tank. Use channel-locking pliers plus penetrating oil and extreme care to avoid breakage. Clamp a well-padded locking plier/wrench around the flush valve to keep it from rotating inside the tank.

Install the new flush valve (see image) according to the directions.
install new flush valve

The rubber gasket goes on the inside of the tank to prevent leakage. The flat washer fits on the outside to prevent tank damage.

Use new brass tank hold-down bolts, which will remain workable. Tighten the bolts just enough to compress the tank’s soft rubber gasket and keep it from leaking.

Install the water supply riser to the tank and turn on the water.

5) Fixing The Refill Valve

Brass-style toilet refill valves can often be repaired. To take a valve apart, remove the lever’s screws. This allows you to lift out the float arm and valve plunger. Check the flat rubber washer on the end of the plunger. If it’s worn, you can pull out with pliers and either turn it around or replace it. This procedure usually corrects an overfilling problem. Next reassemble the valve. If the tank continues to overfill, check to make sure the operating lever at the end of the float arm is functioning properly.

New Refill Valve
To replace the entire refill valve assembly, first turn off the water supply. The tank should then be flushed and sponged out, as detailed previously. Remove the inlet nut and riser tube from the bottom of the refill valve beneath the tank. Hold the refill valve inside the tank with a padding locking plier/wrench to keep it from turning, and remove the nut beneath the tank. With the nut off, the refill valve assembly can be lifted out and a new one inserted in its place. See image. Follow the exact instructions included with the unit you purchase.
new refill valve

Finally, reconnect the riser tube and turn the water on. The tank should fill, allowing you to adjust the water level according to the instructions that were included with the valve.

Anti-Siphon Valves
The best refill valves offer anti-siphon protection. In fact, this may be a requirement. This protection prevents back siphonage of toilet tank water into your home’s potable water supply system if a vacuum occurs in the toilet’s water supply system. Whether or not this is a code requirement, the anti-siphon valve is a good idea to protect your family and public health.

Check your state and local codes before starting any project. Follow all safety precautions. Information in this document has been furnished by the North American Retail Hardware Association (NRHA) and associated contributors. Every effort has been made to ensure accuracy and safety. Neither NRHA, any contributor nor the retailer can be held responsible for damages or injuries resulting from the use of the information in this document.

This step by step learning guide was provide by Ace Hardware. See more at

4 Comments » for How To Repair a Toilet
  1. Lawrence says:

    I am getting no water in my toilet tank at all. So we thought it is a defective supply tube or valve that is by wall. We cut off water supply and tried to remove but cannot. So I need a plumber.
    What do you recommend or suggestion?

  2. Peter says:

    I have installed a new refill valve, following the instructions as to washer placement inside the tank and tightening the nuts under the tank as handtight as I could get them. However the tank still leaks. The instructions say handtight only, and I don’t want to bust anything using pliers. I cleaned the tank out before installation, but could some microscopic crud be interfering with the washer? Or could the tank be cracked? Any suggestions?

    • Weaver's Ace Hardware says:

      Here are some possibilities to check- Fill valve shank gasket leak: Check the shank gasket where the fill valve attaches to the tank. The fill valve is the valve that allows water to enter into the tank. The shank gasket is attached to the fill valve on the inside of the tank. This type of leak can also usually be detected by the colored water test. Check for possible cracks in the porcelain around or near the gasket. If no cracks are detectable in the porcelain, you may be able to just tighten the shank nut underneath the tank to stop the leak. We suggest you tighten the nut a 1/4 turn at a time while checking to see if the leak stops. If the leak is still there, you probably need to replace the gasket.
      Leak from the fill valve refill tube: If the leak appears to be coming from the back, near the top of the tank, then check to make sure the refill tube has not come loose from the overflow tube on the flush valve.
      Leaking supply line: Check for water dripping from the nuts on each end of the supply line, where the line attaches both to the inlet of the toilet’s fill valve (on one end of the flex) and the shut-off valve on the wall (at the other end of the flex). If you have a rigid supply line, you can try replacing the supply washers.

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