Leak Detection
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Plain-English article
High Water Bill in Thornton, CO: Causes and What to Check
A bill that doubles without a change in your household usually has a cause you can find. Start by reading the meter, then work through the usual suspects.
By the Thornton Plumbing Co. team ·
Compare your bill to last year
Look at the usage portion, not the dollar total. Compare the same month last year, since summer irrigation and winter low use make month-to-month comparisons misleading.
If the usage is much higher, check whether anything changed: guests, a new baby, a filled pool or spa, a new sprinkler zone or a new landscape. When the reading stays put, a leak is the next suspect.
Read the meter
Turn off everything that uses water and watch the leak indicator on the meter. Any movement means water is flowing. Record the reading, wait an hour, and read it again.
If the number changed, you have a leak somewhere between the meter and the fixtures. The guide on how to find a water leak walks through the order of checks. For help with hidden leaks, see leak detection.
Sprinklers and seasonal use
Colorado lawns need irrigation in summer, and a sprinkler schedule that is too long or has a broken head can add a large amount to the bill. Check that each zone runs the time you set and look for geysers, soggy areas and misting heads.
Thornton's drought rules limit lawn watering to no more than two days per week and ban outdoor watering from ten in the morning to six in the evening when restrictions are in effect. Check the city's current notices.
Likely causes and how to check
Match what you see to the usual suspect.
| Clue | Likely cause | Check |
|---|---|---|
| Meter moves with everything off | A hidden leak | Isolate sections and toilet dye test |
| Bill peaks in summer | Irrigation | Run zones and look for broken heads |
| Gradual climb over months | A slow fixture leak | Toilets and faucets |
| One odd spike | Billing error or a one-time fill | Ask for a meter test |
Fixture leaks
A toilet with a bad flapper, a dripping faucet and a leaking hose bib can waste thousands of gallons a year. Use food coloring in toilet tanks, and check under sinks.
A water softener or a filter that cycles constantly can also use water. If your softener runs a regeneration every night, check the settings.
Billing and meter issues
Sometimes the bill is wrong. A meter can be misread, estimated or faulty. Ask the city for a meter test if the reading does not match your own. Keep photos of the meter with dates.
If a leak is found and fixed, ask the utility whether it has an adjustment policy. Practices vary, and they may want proof of repair.
Seasonal swings and hard water
Hard water scale can narrow pipe over time, and an aging water heater that leaks quietly adds to use. A pressure regulator that is set too high can push flow through small leaks.
If you have a pool or spa, filling it adds a lot of water. See spa plumbing for leaks around the equipment.
Read the bill before you hunt
Look at the usage line, not just the total. Compare the same months in prior years, since summer irrigation and a house full of guests change usage. A sudden step up that holds all month is a better clue than a one-time spike.
Check the billing period too. A longer cycle or an estimated read can bunch up usage. Know whether your bill includes sewer, trash or other charges that change separately.
The meter test
Turn off every fixture and appliance, the ice maker and the irrigation controller. Find the meter, and look at the small triangle or dial that spins with any flow. If it moves, water is flowing somewhere. Note the number on the register, leave everything off for an hour and read it a second time.
If the reading changed, you have a leak. If it did not, the usage is coming from what you do, not what is broken.
The usual suspects
A toilet that runs is the top cause. Next are a leaking irrigation valve, a dripping spigot, a water heater relief valve that weeps and a slab or yard line leak. Landscape watering can double a summer bill. See slab leak detection and water line repair for hidden leaks.
Look for green, soggy patches in the yard. Listen at the main for hissing. Check the water heater tank and the bottoms of cabinets.
Talking to the city
Thornton's utilities department can explain how your bill is calculated and check the meter read. Ask whether the meter has been tested and whether leak adjustments exist. Policies change, so ask for the current rule and get it in writing.
If you fix a leak, keep the repair invoice. It documents the repair and supports an adjustment request where one is available.
Seasonal use that looks like a leak
Colorado summers are dry, and a lawn on a timer can use more water in a month than the whole house does indoors. Look at your controller and the number of minutes per zone, and compare it with the city's rules for watering days. Overspray onto concrete and a broken head that sprays a fence are common wastes.
If you filled a pool, a spa or a large tank, or hosted a long visit, expect a spike. Note the dates, so you can explain the bill to yourself later.
Make a small log
For two weeks, read the meter at the same time each morning and jot down the figure. A steady daily number points to normal use. A rise on days when nobody was home points to a leak, and an irrigation schedule that runs on certain days will show as a jump on those days.
Quick answers
Asked about high water bill
Common causes are a leak, sprinklers, guests or a seasonal event. Read the meter to rule out a leak.
Yes. A meter that moves while everything is off suggests one.
Often yes. Ask the utility about a meter test.
Yes, usually in the next billing cycle.
Connected services
Water Line Repair & Replacement
Mend or renew the buried pipe between the city's meter and your foundation when it breaks or corrodes. Open page
Toilet Repair & Installation
Repair a toilet that runs, rocks, flushes weakly or overflows, or swap in a new one. Open page
Related reading
Tracking down a hidden leak
Reading the meter, dyeing the toilet tank and walking each room will turn up most leaks. Here is the order to do them in. Open page
Running toilet fix
A running toilet can waste thousands of gallons a year. The fix is usually a flapper, a fill valve or a chain, and takes minutes. Open page
Sprinkler backflow preventer winter care
The brass backflow assembly on your sprinkler line cracks if it freezes. Here is what it does and how to protect it. Open page
Bill climbing for no reason?
Call to talk through the pattern in your bills with a dispatcher.