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High Water Bill? How to Tell If a Slab Leak Is the Cause

A leak does not announce itself, but it does show up on paper. Here is how to read your bill, rule out the usual suspects and decide whether to call a plumber.

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By Pomona Slab Leak Pros · Updated November 2026

What a leak looks like on your bill

Technician checking a warm home floor with a thermal imaging camera

Usage that stays high across several billing periods with no change in your household.
A jump compared with the same month last year.
Steady use in months when you normally use less, such as winter.

Many California utilities bill in hundred cubic feet (CCF). One CCF is about 748 gallons, so a bill that climbs by several CCF is a lot of water. Check the units on your bill before you compare.

Rule out the usual suspects first

Irrigation: new timers, longer cycles or broken heads
Toilets: a worn flapper can waste a lot of water
A new habit: a pool fill, a new appliance, more people at home
Seasonal use: summer watering can raise a bill without any leak

Run the meter test

If nothing above explains the bill, run the 30-minute meter test. Turn off all water, then check whether the meter keeps moving. Steps are in how to tell if you have a slab leak.

Talk to your water utility

Customers of the City of Pomona can contact Customer Service at (909) 620-2241, Monday to Thursday, 7:30 a.m. to 6:00 p.m., according to the City’s Utility Billing page; check that page for current hours. The page lists water meter leaks as a reportable issue but does not describe leak adjustments or bill credits, so ask Customer Service whether any adjustment applies after a repair.

Keep records

Copies of the high bills and the bills before them
Photos of the meter reading and any damage
The plumber’s leak report and repair invoice
Notes of every call with the utility or your insurer

These help with any utility conversation and with a claim. See whether homeowners insurance covers a slab leak.

If the meter says you have a leak

Shut off the main if you see water or damage.
Call a plumber to locate the leak: slab leak detection.
Ask for options and prices: repair options and costs.

Frequently asked questions

How much can a slab leak add to my bill?

It depends on the size of the leak and how long it ran. A small leak running all day adds up over a billing period, which is why bills are a useful early clue.

Will the utility reduce my bill after a repair?

Some utilities offer adjustments and some do not. Ask your utility directly, and keep the repair invoice and leak report.

Can a high bill come from a leak outside the house?

Yes. A leak on the line between the meter and the house can raise usage too. The meter test helps tell which side of the shutoff valve it is on.

Should I call a plumber or the utility first?

If you see water, shut the main and call a plumber. If the meter keeps moving after the main is closed, the leak is before the house, and the utility may need to be involved.

Sources: City of Pomona Utility Billing

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