Why Does My Toilet Keep Running? (And How Much Water It's Wasting)

That constant hissing or trickling from the bathroom isn't just annoying. A running toilet can quietly waste a lot of water. According to the EPA's WaterSense program, a leaky toilet can waste about 200 gallons of water every day. That shows up on your water bill.

Here's what usually causes it, a simple test you can do yourself, and when it's time to call a plumber.

How a toilet tank works (in 30 seconds)

When you flush, a rubber flapper at the bottom of the tank lifts and lets water rush into the bowl. Then the flapper closes, and the fill valve refills the tank until a float tells it to stop. If any part of that cycle doesn't seal or shut off properly, water keeps running.

The most common causes

1. A worn or warped flapper
This is the most common culprit. Over time the rubber flapper gets stiff, warped or coated with minerals, so it doesn't seal. Water slowly leaks into the bowl and the tank keeps refilling.

2. A fill valve that won't shut off
If the fill valve is worn or set too high, water keeps flowing and spills into the overflow tube.

3. The float is set too high
If the float lets the water level rise above the overflow tube, water drains away constantly.

4. A tangled or too-short chain
The chain between the handle and the flapper can keep the flapper from closing if it's too short or tangled.

5. A cracked overflow tube or tank
Less common, but a crack can cause constant running or leaks. That usually means replacing parts or the toilet.

Try the dye test: find a silent leak

Not every leak is loud. Here's a simple test the EPA recommends:

1. Put a few drops of food coloring in the toilet tank (not the bowl).
2. Don't flush for about 10 to 15 minutes.
3. Check the bowl. If color shows up in the bowl, water is leaking past the flapper.

Afterward, flush to clear the coloring.

When to call a plumber

Simple fixes like adjusting the chain can be easy. Call us if:

• The toilet keeps running after you've checked the chain and float
• The dye test shows a leak
• There's water leaking at the base of the toilet
• The toilet wobbles (a worn seal underneath can damage your floor)
• You see cracks in the tank or bowl
• You'd rather it just get fixed right the first time

What we'll do

We'll find the actual cause, whether that's a worn flapper, a failing fill valve or a cracked tank. Then we'll give you a written price before any work begins. Most running toilets are fixed on the first visit. If your toilet is cracked or keeps having problems, we'll explain whether a repair or a replacement makes more sense.

Landlords: a running toilet in a rental wastes water every day. We'll coordinate directly with your tenant and get your approval on the price by phone.

Stop the running

We fix running toilets across Springfield, Annandale, Fairfax and all of Northern Virginia, with same-day service in most cases.

Call Plum Pro at (202) 557-9978, open 7 days, 9 AM–7 PM, or request service online.