Start by comparing the bill against your own prior usage — not just the dollar total, since rates, fees, and billing-period length can all change independently of your water use. Then work through occupancy changes, outdoor watering, toilets, and finally the meter itself.
Rule out the obvious first
Confirm the billing dates and reading type (actual vs. estimated), then compare volume used against the same period last year or your normal seasonal pattern. Guests, more laundry, a filled pool, new landscaping, or a tenant change can all legitimately raise usage without any leak at all.
Check outdoor use, then toilets
Outdoor leaks can be less visible than indoor ones — check hose bibs, irrigation valves, emitters, and valve boxes for standing water or hissing. Then dye-test every toilet: EPA WaterSense’s method is a few drops of food coloring in the tank, wait ~10 minutes without flushing, and check the bowl for color — then flush to avoid staining. A silent tank-to-bowl leak is one of the most common causes of a surprise bill.
Read the meter correctly
Turn off every faucet, stop appliances, irrigation, and treatment-equipment regeneration, then record the meter, wait, and check again. Movement means water is being used or lost somewhere in the system. If you can isolate branches (irrigation, recirculation, individual toilets) one at a time, movement stopping after a branch is shut off points to that branch — but don’t force old valves.
If the meter doesn’t move
The bill may reflect a longer billing period, an estimated or corrected reading, an intermittent leak the test window missed, or genuinely higher usage. Contact your provider for billing questions — a plumber can document a repair but can’t correct the bill itself. Some providers offer a leak-adjustment credit after a qualifying repair; ask directly about eligibility and documentation.
Quick answers
How much of an increase means a leak? There’s no universal percentage — compare against your own normal usage and explainable changes.
Can a running toilet really spike a bill? Yes — a quiet tank-to-bowl leak can run continuously.
How long should I watch the meter? A short check catches big leaks; smaller or intermittent ones may need a longer, professionally supervised test.
