Running toilet? How to find the leak and cut your water bill

Step 1: Confirm the toilet is leaking

Some toilet leaks are loud. Others are silent. EPA WaterSense suggests two simple checks (EPA WaterSense):

• Dye test. Put a few drops of food coloring in the toilet tank and wait 10 minutes without flushing. If color shows up in the bowl, the tank is leaking. Flush afterward (EPA WaterSense).
• Meter test. Read your water meter, don’t use any water for two hours, then read it again. If the reading changed, you probably have a leak somewhere in the house (EPA WaterSense).
• Winter water use. EPA says a family of four using more than 12,000 gallons a month in winter probably has a serious leak (EPA WaterSense). Check the usage on your water bill.

Other signs: the toilet refills or hisses when no one has flushed, water keeps trickling into the bowl, or the handle has to be jiggled to stop it.

Step 2: Find the part that’s failing

Most running toilets come down to two parts inside the tank. Turn off the water at the valve behind the toilet before you work on it.

• The flapper. This rubber seal at the bottom of the tank lets water into the bowl when you flush. EPA says a worn flapper can cause phantom flushes, when the toilet refills without anyone flushing. It suggests replacing the flapper at least every five years (EPA WaterSense). Also check that the chain isn’t too tight or tangled.
• The fill valve. This valve refills the tank after a flush. If it sticks open, water keeps flowing into the overflow tube. EPA’s leak guide says a stuck fill valve can waste up to 4,300 gallons a day, or as much as $1,400 a month in water costs (EPA WaterSense).
• Water level. If water is running into the overflow tube, the fill level may be set too high. Many fill valves have an adjustment screw or clip. Follow the instructions on the part.

Take the old part to the hardware store so you can match it. Flappers come in different sizes, and the right fit matters for a good seal.

When to call a plumber

• The tank still leaks after you replace the flapper and fill valve.
• Water is leaking at the base of the toilet, from the tank bolts or from the supply line. That can damage floors and ceilings.
• The shutoff valve behind the toilet won’t turn or leaks itself.
• Your meter test shows a leak but the toilet passes the dye test. EPA’s leak checklist suggests checking faucets, showerheads and irrigation, and calling a licensed plumber for leaks you can’t find or fix (EPA WaterSense).

In Illinois, plumbing work generally has to be done by a licensed plumber. The law makes an exception for an owner or renter who lives in a single-family home and repairs its plumbing, as long as the work meets the Illinois State Plumbing Code and anyone helping is a licensed plumber (225 ILCS 320/3). You can check a plumber’s license with the Illinois Department of Public Health.

Replacing an old toilet

If your toilet is old or cracked, replacing it can cut your water use for years. Toilets with the WaterSense label use 1.28 gallons per flush or less, 20% less than the 1.6-gallon federal standard. EPA says replacing old, inefficient toilets with WaterSense models can save a family about 13,000 gallons and about $170 a year, or $3,400 over the toilets’ lifetime. Some water utilities offer rebates, so check with yours first (EPA WaterSense).

Hire carefully

• Ask for a written estimate that lists the parts and labor before work starts.
• For home repair work over $1,000, Illinois law requires a written contract, and contractors must give you the “Home Repair: Know Your Consumer Rights” brochure (815 ILCS 513/15, Illinois Attorney General).
• Watch for high-pressure sales and big up-front payments (FTC).

Got a high bill from a leak? See our guide to lowering your water bill, plus our plumbing and drain cleaning guides.