How to find and fix a toilet leak

Toilets are one of the likeliest places in the home to find leaks. These leaks can waste thousands of gallons per month! Save money and water by fixing simple toilet leaks yourself. Follow these easy steps.
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Step 1: Find the leak

A close-up illustration of two hands dumping two pill-sized dye tabs out of a ripped packet.

Sometimes it's easy to tell that your toilet is leaking: you hear the sound of running water or a faint hissing or trickling. But many times, water flows through the tank silently, which is why toilet leaks are often overlooked.

Order a free toilet leak detection kit

To check for toilet leaks:

  • Lift the toilet tank lid.
  • Drop one dye tablet from your free toilet leak detection kit or several drops of food coloring into the tank (do not flush).
  • Wait at least 10 minutes and check the bowl of the toilet. If there is dye in the bowl, the toilet has a leak.

Step 2: Determine your toilet type

There are two common types of toilets: float-ball-style and vertical-float-style. Compare the diagrams below to your toilet to determine the style you have in your home.

Toilet type 1: float ball-style

Illustrated diagram of the parts inside of a float-ball style toilet tank. The parts in the diagram are listed in the webpage text in the numbered list.

This type of toilet uses a ball filled with air to regulate how much water fills the tank. This type of toilet has been commonly used for decades. The parts of this style of toilet are:

  1. Water inlet shut-off valve
  2. Flapper valve (flapper)
  3. Valve seat
  4. Chain
  5. Overflow tube
  6. Float arm
  7. Float ball
  8. Fill valve
  9. Handle
  10. Float adjustment screw

These numbers correspond with the numbers in the diagram to the right and the numbers in the text in the sections below.

Toilet type 2: vertical float-style

Illustrated diagram of the parts inside of a vertical float style toilet tank. The parts in the diagram are listed in the webpage text in the numbered list.

This type of toilet uses a vertical float on a pipe to regulate how much water fills the tank. This type of toilet is a newer type of design. The parts of this style of toilet are:

2. Flapper valve (flapper)

5. Overflow tube

8. Fill valve

11. Vertical float

12. Water level adjustment spring clip

These numbers correspond with the numbers in the diagram to the right and the numbers in the text in the sections below.

Step 3: Gather tools

  • An adjustable crescent wrench
  • Replacement flapper valve (flapper)
  • Hand towel

Step 4: Check the chain and handle

If you have to jiggle the handle to keep the toilet from running, it may have a misaligned flapper valve (2), a loose handle (9), or a chain that's the wrong length (4).

To fix: Adjust the chain (4). Make sure the chain is neither too long nor too short. Tighten the nut that holds the toilet handle to the tank. If that doesn't work, you may need to replace the handle.

Step 5: Check the flapper

The flapper valve (2) may not be sitting properly on the valve seat (3), or it may need to be replaced. Over time, the flapper's rubber material deteriorates. If you gently rub the flapper and get streaks on your fingers, you should replace it right away.

To fix: Begin by turning the water inlet shutoff valve clockwise to turn the water off (1). Flush the toilet to drain the tank. Check the valve seat (3) for corrosion and clean it if necessary. Check the flapper valve (2) to make sure it lines up properly with the valve seat. If needed, you can purchase a replacement flapper at a hardware store. Some large grocery stores carry them as well. Take your old flapper with you to make sure you get an identical one. After installing the new flapper valve, open the water inlet shutoff valve (1) and flush to test.

Step 6: Check the overflow tube

If the water level in the tank is too high, it may continuously spill into the overflow tube (5), creating a large leak. If the water level is too low, you may not get an efficient flush. The correct water level is about 1/2–1″ below the top of the overflow tube.

To fix: To adjust the water level, you must adjust the height at which the float shuts off the fill valve. Manufacturers have several variations on fill valve mechanisms, but they all include a method for adjusting the water level. Close inspection should make clear how to adjust your particular fill valve.

  • Toilet type 1: In float-ball-style toilets, a float hangs at the end of a metal or plastic float arm (7). Where that arm connects to the fill valve (8) there is usually a screw (10). Adjusting that screw will change the level at which the water valve shuts off. If there is no screw or it is already at its maximum, you may be able to carefully bend the metal arm (6) into place.
  • Toilet Type 2: In vertical-float-style toilets, the float (11) is often a collar around the fill valve (8) that rides up and down vertically. The float typically has a spring clip (12) connecting it to a metal rod that connects to the fill valve shutoff. Squeeze the spring clip to slide the float up or down the metal rod.

Other problems

While some toilet repairs are easy, others are more complicated. Know your limitations—call a plumber if you have any concerns about how to make a repair. The Water Bureau is not responsible for any damage to your home or toilet due to faulty repairs.

Replacing an old toilet and how to choose a new toilet

Often, it costs more to repair a leaking toilet than to replace it with a new one. Federal law requires that all toilets sold today use 1.6 gallons or less per flush. Water-efficient toilets that use 1.28 gallons per flush are widely available, as are dual-flush models.

Today it's easy to find a water saving and high-performance toilet thanks to WaterSense, a national program sponsored by the United States Environmental Protection Agency. Only toilets that are 20 percent more water efficient than standard toilets and pass rigorous independent performance testing receive the WaterSense label. Look to make sure that any toilet you buy has the WaterSense label.

Just as important as a toilet's efficiency and performance is choosing the right size and shape. Luckily, there are some helpful guides out there to help ease your search for a new porcelain throne. When replacing an older toilet, make sure you know which size to look for. There are several factors to consider:

  • Rough-in is the distance from the flange bolts (the bolts that anchor your toilet to the floor) to the wall behind your toilet. The average rough-in is 12 inches in most homes.
  • Footprint is the area the bottom of your toilet covers on the floor. If a smaller footprint is chosen, you might have to patch the floor or replace some tiles.
  • Bowl height is the distance from the floor to the top rim of the bowl, not including the toilet seat. The typical height for American toilets is about 15 inches. However, many people choose to replace their older toilets with ADA or "comfort" models with a height of about 18 inches.

This guide contains tips to consider before purchasing a toilet and explains toilet size considerations. You can also use this searchable toilet database to filter the features and sizes you are looking for to find your next toilet.

If you purchase a new WaterSense-labeled toilet and recycle your older toilet, apply for the Water Bureau's toilet replacement rebate program.

Apply for a WaterSense toilet rebate