Sudden high water bill — no visible leak
No dripping faucets? Still high? Run the overnight meter test and isolate indoor vs outdoor.
Direct answer
Most "no visible leak" spikes are still leaks: underground service line, slab leak, running toilet you can't hear, or irrigation valve stuck open. The overnight meter test with everything off is the fastest free diagnostic.
Overnight meter test (step-by-step)
- Turn off ALL water use (indoor + outdoor). No flushing, no ice makers, no sprinklers.
- Locate meter (usually curb box). Note exact reading + photo. Note leak indicator (small dial/triangle).
- Wait 4–12 hours (overnight best for small leaks).
- Re-read without using water. Any change = leak on your side of meter.
Isolate the leak
After test shows movement: find main shutoff (near water heater). Shut it off. Re-test meter. Movement continues = leak between meter and shutoff (service line). No movement = leak inside house.
Worked example
Bill: 25 CCF vs 6 CCF average. Overnight test: +48 gallons moved. Main shutoff closed, meter still moved 3 gal/hr. Service line leak confirmed by plumber. Utility credited after repair receipt.
Primary sources & next steps
- Portland Water Bureau leak test: portland.gov
- Many utilities (SAWS, Raleigh, etc.) publish identical procedures.
- Contact your utility for free meter test or leak assistance before expensive repairs.