Why Is My Water Bill So High? 8 Possible Causes (and How to Find the Leak)

A water bill that jumps without warning is a good reason to look for a leak. Some causes are simple to find yourself. If the simple causes are ruled out, a hidden leak under the slab or in the yard line remains a possibility.

Work through the causes below in order. They go from easiest to check to hardest.

First: compare gallons, not dollars

Rates and fees change, so the dollar amount alone can mislead you. Look at the usage figure on your bill, shown in gallons or units, and compare it with the same period last year and the last few months. If usage has climbed while your household habits have not changed, water may be going somewhere you are not expecting.

Also check whether the bill says estimated. An estimated reading followed by an actual reading can make one bill look unusually high. If you think the reading is wrong, contact your water provider and ask for it to be checked.

8 possible causes of a high water bill

1. A running or leaking toilet

A toilet can waste water silently. A worn flapper can let water trickle from the tank into the bowl all day and night, sometimes without a sound. Test it the way EPA WaterSense suggests: add a few drops of food coloring to the tank, wait 10 minutes without flushing, and look in the bowl. Color in the bowl means a leak. Replacing a worn flapper can fix it.

2. Dripping taps and showerheads

A steady drip can add up over a billing period. Check every tap, showerhead and outdoor hose bib, and replace worn washers or cartridges.

3. Irrigation problems

Irrigation can use a lot of water. A broken sprinkler head, a cracked lateral line or a valve that does not close fully can waste water, sometimes overnight when no one sees it. Walk the yard while the system runs, check the controller schedule after any power outage, and look for soggy patches or water running onto the street.

4. The pool auto-fill

If your pool has an automatic fill valve, it quietly replaces whatever the pool loses. Normal evaporation is expected, but a pool leak or a stuck fill valve can send water straight onto your bill. Turn off the auto-fill for a few days and mark the water level to see how fast it drops.

5. Water softeners, filters and appliances

A water softener can regenerate more often than it should if a setting is wrong. Ice maker and dishwasher supply lines can also leak behind cabinets. Check under sinks and behind appliances for damp spots.

6. A leaking water heater

Look around the base of the water heater and at the temperature and pressure relief valve pipe. Water there can mean the heater or valve needs attention.

7. A leak in the main water line

The line between your meter and your house runs underground. A leak here can show up as a soggy strip of lawn, a muddy meter box or a patch of grass that grows faster than the rest. In sandy soil, the water can drain away without surfacing at all. See our page on water line leak detection.

8. A hidden slab leak

If every fixture checks out and the meter still moves with the house shut down, a leak under the slab is a possibility. Warm floors, damp flooring and the sound of running water are possible signs. Our guide to slab leak signs covers them in detail.

How to narrow down the source

1. Shut everything off. Taps, toilets, irrigation, pool auto-fill, softener, ice maker and appliances.
2. Read the meter. If the leak indicator moves, water may be escaping. Note the full reading.
3. Do the toilet dye test on every toilet and fix any that leak, then check the meter again.
4. Close the main valve at the house. If the meter stops, the leak is likely inside or under the house. If it keeps moving, the leak may be on the yard line.
5. Close the water heater's cold supply valve (main valve open). If the meter stops now, the leak is likely on the hot side.
6. Call a leak detection plumber once you know a leak exists but cannot see it.

When to contact your water provider

Contact your water provider if the meter itself is leaking, water is coming from the street side of the meter, or you think the bill was misread. Water providers sometimes have policies about adjusting bills after a repaired leak, so ask what documentation they need. Keep your repair invoice and meter readings.

Frequently asked questions

Can a running toilet really raise my bill that much?

It can. A toilet that runs or trickles all day uses water around the clock.

Why is my bill high when I was away?

If no one was home, usage can point to a leak, an irrigation schedule, a pool auto-fill or an appliance such as a softener. Do the meter test with everything off.

Will my water provider adjust my bill after a leak?

Some providers have leak adjustment policies and some do not. Ask yours, and keep proof of the repair.

Who fixes a leak between the meter and the house?

Some utilities make the homeowner responsible for the line from the meter to the house. Check with City of Delray Beach Utilities to confirm for your property.

This guide is general information, not professional advice for your home. Delray Beach Leak Detection Help is a referral service that connects callers with independent local plumbers.