“My water bill doubled”: leak, estimated read, or rate change

"Hope it was a fluke." I understand the instinct, but a doubled water bill is almost never random. It's usually one of three things, and you can narrow it down tonight with the bill on the kitchen table and a flashlight.

Suspect one: the read

Look at the usage section of the bill. Two lines matter.

Actual or estimated. Utilities sometimes estimate a reading when they can't get to the meter, then correct it on the next actual read. If last month was estimated low and this month is an actual read, this bill may be catching up two months of water in one. If this bill is the estimated one, it may simply be wrong.

Days in the billing period. A 35-day period after a 28-day one will bill more water for the same habits. That won't double a bill on its own, but combined with a catch-up read it can come close.

Suspect two: the rate

Find the rate section, or check the utility's website for a rate change notice. Many water utilities use tiered rates, where each gallon above a threshold costs more than the ones before it. If the rates went up, or your usage crossed into a higher tier, the bill can jump faster than your usage did. Some cities also bill sewer based on water use, so one jump shows up twice.

Suspect three: a leak

If the read is actual, the period is normal and the rates haven't changed, the water went somewhere. Most household leaks are silent. The EPA's WaterSense program says household leaks can waste nearly 10,000 gallons of water a year in an average home, and toilets are among the most common culprits.

Which suspect to check first

What the bill shows	Most likely	First step
Current read marked estimated	Estimated read	Read the meter yourself and call for a correction
Last read estimated, this one actual	Catch-up bill	Ask the utility to spread or verify it
Actual read, rates changed	Rate change or tier jump	Compare usage in gallons to last month
Actual read, same rates, usage way up	Leak	Meter test tonight

The meter test

Your meter is usually in a covered box near the curb or on an outside wall. Many meters have a small leak indicator, a triangle or star-shaped dial that spins when any water is moving.

1. Turn off every tap, the dishwasher, the washing machine, the ice maker and the irrigation.
2. Look at the leak indicator, or write down the full meter reading.
3. Wait 15 minutes without using any water.
4. Look again.

If the indicator is spinning or the reading changed, water is running somewhere while you're using none. That's a leak.

Finding it

• Toilets first. Put a few drops of food coloring in the tank and wait, without flushing. If color shows up in the bowl, the flapper is leaking. A flapper is an inexpensive part.
• Listen at the toilet for the tank refilling on its own.
• Outdoor spigots and irrigation. A broken sprinkler line can leak underground for weeks.
• Water heater relief valve and drain line.
• Between the meter and the house. If you shut off the main valve at the house and the meter still moves, the leak is in the service line on your side of the meter, which is usually your responsibility to repair.

Why the verdict is a call

Whatever you find, call the utility before the due date. Bring three things: the meter test result, your own meter reading, and the date you fixed anything you found.

What you're asking for depends on the suspect. For an estimated read, ask for a re-read and a corrected bill. For a catch-up bill, ask whether it can be spread over a few months. For a leak, ask whether they have a leak adjustment policy. Many utilities will credit part of the excess water, or the sewer portion of it, once you show a repair was made, but you usually have to ask and you may need a receipt.

And if you find nothing and the meter is still, ask them to test the meter. It's rare, but meters can be wrong too.