A puddle next to the toilet is easy to blame on the wax ring, but the water often comes from higher up: the shut-off valve (sometimes called the “tap” or angle stop), the supply line, the fill valve nut or the tank bolts. These are generally simpler to fix than a leak at the floor seal. This guide helps you pinpoint the source and handle the repairs that suit a DIYer.
Where is the water coming from?
Dry everything first, then lay strips of dry paper towel or toilet paper around the suspected spots. Check again after a flush and after a few minutes. The first place the paper gets wet usually points to the source.
| Where the water appears | Likely source |
|---|---|
| At the wall or floor valve, dripping from the stem or handle | Shut-off valve packing nut or the valve itself |
| Along the flexible hose or at either end of it | Supply line or its nut |
| Underneath the tank where the hose meets it | Fill valve nut or washer |
| Around the bolts inside or under the tank | Tank bolt washers |
| Between the tank and the bowl | Tank-to-bowl gasket |
| At the base of the toilet on the floor | Possibly the wax ring or flange |
Water can run along surfaces before it drips, so check twice before buying parts.
Before you start
- Close the shut-off valve by turning it clockwise. If it will not turn, or it leaks as you try to turn it, you may need to close the main water valve to the house instead.
- Flush to empty the tank, and sponge out what remains.
- Have towels, a small bucket and an adjustable wrench ready.
- Keep water away from outlets and electrical devices. If water has reached an outlet, shut off power to that circuit at the breaker panel before touching anything, and call an electrician if you are unsure.
Leaking toilet shut-off valve (the “tap”)
In many countries “tap” simply means faucet, so a leaking toilet tap usually refers to the small shut-off valve on the supply pipe. There are two common leak spots.
Packing nut leak
If water seeps around the valve stem or handle, the packing nut or the packing washer behind it may be loose or worn. With the supply off at the main valve, you can try snugging the packing nut a small amount (an eighth to a quarter turn). Do not overtighten, since this can make the valve stiff or damage it. If the leak continues, the valve is better replaced.
Valve replacement
Old shut-off valves can seize or leak when disturbed. To replace one:
- Shut off the main water supply and open a faucet to relieve pressure.
- Disconnect the supply line from the valve and keep towels ready for residual water.
- Remove the old valve. The method depends on the pipe type: threaded, compression or soldered. Compression valves can be unscrewed or the nut loosened, while soldered ones usually need a plumber or soldering skills.
- Fit the new valve using the right connection for your pipe and thread sealant such as PTFE tape on tapered threads, if that applies to your valve.
- Reconnect the line, turn on the main supply and check for drips.
If the pipe is corroded or the valve is soldered on, hire a plumber. A damaged pipe can leak more seriously when it is disturbed.
Leaking supply line
Supply lines, particularly older rigid or braided ones, can fail at the connections or in the hose. Signs include drips at the nuts, rust, bulges or frayed braid. Many plumbers suggest inspecting them occasionally and replacing them every several years, and always when you replace a toilet.
To replace one:
- Turn off the water and empty the tank.
- Loosen the nut at the shut-off valve and the nut at the fill valve, using a wrench, and catch the water.
- Fit a new line of the correct length and connection size. Hand-tighten the nuts, then give about a quarter turn with a wrench. Over-tightening can damage the washers and cracks plastic fittings.
- Turn on the water slowly and check for drips along the line and at both ends.
If a line has burst or is spraying, shut off the main water immediately.
Leaking fill valve nut
The fill valve mounts through a hole in the tank bottom, held by a large nut with a rubber washer. If water drips from beneath the tank at that point, the washer may be worn, misaligned or the nut too loose. Turn off the water, drain the tank, disconnect the supply line, and check the washer. Hand-tighten the nut about a quarter turn beyond snug, and replace the washer or the whole fill valve if the leak persists. If you are replacing the fill valve for another reason, see how it relates to a tank leaking into the bowl.
Leaking tank bolts
Two-piece toilets are held together with two or three tank bolts that pass through the tank bottom and have rubber washers. If the washers degrade, water can seep around them and drip from the underside.
- Turn off the water and empty the tank.
- Hold the bolt head inside the tank with a screwdriver, and loosen the nut underneath.
- Replace the rubber washers (and metal washers, if present) with new ones. Brass bolts and washers are available in kits.
- Tighten the nuts evenly and gradually, alternating between bolts, until the tank sits level and snug. Stop as soon as the leak stops.
Do not overtighten. Porcelain can crack under pressure, and a cracked tank has to be replaced.
Leak at the tank-to-bowl joint
A large rubber gasket (sometimes called a spud washer or tank-to-bowl gasket) seals the tank outlet to the bowl inlet. If it fails, water can drip at the joint. Replacing it means separating the tank from the bowl, which is manageable for a patient DIYer but involves lifting a heavy tank. Replace the bolts and washers at the same time.
Water at the base: call a plumber
If the water is at the base of the bowl, it could come from the wax ring or flange, from a loose toilet, or from condensation or a leak higher up that has run down. A rocking toilet, a sewage smell, a soft floor or a stain on the ceiling below are signs of a failed seal, a damaged flange or water damage in the floor (once the leak is fixed, see how to fix a ceiling after a leak for the ceiling below). Those repairs involve lifting the toilet and may involve the subfloor, so they are best left to a professional. Stop using the toilet if it is rocking or leaking wastewater. See toilet plumbing basics for how the flange and wax ring fit together.
When to call a plumber
- You cannot get the shut-off valve to close, or it leaks at the pipe.
- The pipe feeding the valve is corroded, soldered or damaged.
- You suspect a leak at the wax ring or flange, or the floor feels soft.
- You cannot find the source after drying and checking.
- A leak has been running for some time and there may be hidden water damage or mold.
If a leak has been active for a while, check your water use too. Our article on how a leaking toilet affects your water bill shows how to estimate that.