A Rising Water Bill Is a Leak Warning: How to Track It Down

By Washington Water Damage Pros · Published 2026-10-16

Read the Usage Line, Not Just the Total

Water bills are built from two different numbers: how much water the household used, and what the utility charges for it. The charge side moves for rate adjustments, seasonal tiers and stormwater fees. The usage side is physical: it reflects water that actually passed through the meter.

Find the consumption figure on your bill or in the utility portal, usually shown in gallons or in units of one hundred cubic feet. Compare the same period a year earlier rather than the month before, because a Washington summer can double outdoor use without anything being wrong. Then compare a wet month with a dry one. A household that uses as much in February as in August has a problem, since irrigation is off in February.

Look for consistency as much as size. A leak that runs day and night shows as a floor under your usage that never drops.

The Meter Test That Takes Fifteen Minutes

The meter is the only device in the house that sees every drop. Find it first: in most Washington cities it sits in a concrete box near the curb, sometimes under a metal lid, and in older homes it may be in the basement or a utility closet. Clear the lid, lift it carefully, and note the reading.

Now close everything. Shut off the irrigation controller, ice maker, water softener and any humidifier, and confirm no fixture is dripping. Photograph the meter face, wait twenty minutes without using water, and photograph it again.

• If the reading changed, water moved while nothing was open.
• A spinning leak indicator confirms flow on its own.
• Shut the main valve where water enters the house and watch again. A meter that still moves points to the service line outside.
• A meter that stops points to a leak inside the walls, under the slab or in an appliance line.

Write the result down with the time. That note saves a plumber an hour of guessing.

Silent Users: Toilets, Softeners, Irrigation and Ice Makers

Toilets are the most common culprit by a wide margin. A flapper that no longer seats lets water trickle from the tank into the bowl all night, quietly enough that nobody hears it. Put food coloring in the tank and check the bowl in fifteen minutes without flushing. Color in the bowl means the flapper is passing; a fill valve that never fully closes does the same with a faint hiss.

Water softeners regenerate on a timer and send brine to the drain, so some use is normal. A unit stuck mid-cycle runs continuously, and eastern Washington homes on hard well water often have one. A failed piston or a float stuck open can send hundreds of gallons down the drain between salt deliveries.

Irrigation is the next largest source, particularly in the Yakima Valley and around Wenatchee, where a system may run for hours before sunrise. A broken head, a cracked lateral or a valve that does not fully close loses water underground where nothing looks wet. Run each zone manually and watch the meter; a zone that keeps drawing after the controller shuts off has a valve problem.

Refrigerator ice makers, humidifiers, hot tubs and hose bibs round out the list. The plastic line behind a refrigerator deserves a yearly look, and an outdoor faucet left connected through a freeze can split behind the wall without a visible sign outdoors.

Leaks Behind Walls and Under Slabs

Not every leak announces itself with a puddle. A supply line inside a wall can weep for weeks; the first clue is often a musty smell in a closet, paint bubbling along a seam, or baseboard gone soft. On the west side, where winter humidity is already high, that dampness does not dry out on its own.

Slab leaks behave differently. Many newer Puget Sound subdivisions are built on slab-on-grade, with supply lines run beneath the concrete. A hot-water leak often leaves a warm patch on the floor, sometimes with faint discoloration at the edges. A cold-water leak leaves a cool, damp area that never quite dries, and the moisture wicks into carpet, tack strip and the bottom plate of nearby walls. In either case you may hear water moving at night.

In a crawl space, check the soil under the vapor barrier and the insulation between joists. Insulation that has sagged or gone dark is holding water from above.

When to Bring In Leak Detection and Moisture Mapping

Call for help when the meter test shows flow, the source is not visible, and shutting valves one at a time has not isolated it. A technician can pressurize sections of the system, listen for escaping water with an acoustic sensor, and scan walls and floors with a thermal camera. Tracer gas is sometimes used on lines buried in concrete.

Moisture mapping is the second half of that visit. Meters read the moisture content of drywall, framing and subfloor, and a thermal scan shows the shape of the wet area. Water travels, so a leak at a second-floor vanity often shows up on a first-floor ceiling two rooms away.

If the leak is already wetting building materials, call (888) 217-0216 and describe where the meter is turning and what you can see. A dispatcher can connect you with an independent local provider who handles both the detection and the dry-out. The same call covers a failed water heater or a frozen burst pipe, both of which tend to declare themselves all at once rather than over a billing cycle.

After the Repair, Watch Two Billing Cycles

A repaired pipe does not automatically mean a dry house. The leak may have been running inside a wall or under a floor for weeks, and the materials around it stay wet after the water stops. Ask for moisture readings before the wall is closed, and keep those numbers with the repair invoice.

Then watch usage. Read the meter the day work finishes, again a week later, and compare the next two bills with the same period last year. A return to baseline confirms the fix; a bill that stays high means a second leak or a fixture still passing water.

Habits That Catch the Next Leak Early

Read the meter once a month, on the same day, and write the number in a note on your phone. The habit takes two minutes and establishes what normal looks like, which is the only way to recognize abnormal.

Walk the house after heavy rain and again after the first freeze. Check under sinks for dark rings, look at the ceiling below upstairs bathrooms, and press the drywall at the bottom of exterior walls. In Seattle, the rainy season hides slow leaks behind siding and in crawl spaces. In Spokane and Yakima, the freeze-thaw cycle splits outdoor lines and irrigation fittings that were not blown out in autumn.

Know where the main shut-off is and test it once a year so it still turns. That valve is the difference between a leak that damages one room and one that runs until someone notices.