Your Water Bill Spiked—Now What? How to Track Down Invisible Leaks Before They Do Real Damage
Opened your bill and did a double take? You’re not alone. Sudden water-use spikes usually mean one of three things: a running fixture, a hidden supply leak, or outdoor/irrigation losses you didn’t notice. The faster you pinpoint the culprit, the less chance it has to warp flooring, feed mold, or undermine your slab.
This guide gives you a step-by-step plan Idaho homeowners can run in under an hour—plus what A+ Drain Cleaning & Plumbing does on a professional leak-detection visit if the basics don’t nail it.
First 10 Minutes: Confirm It’s Real (and Which Side It’s On)
1) Kill all known water use.
No laundry, dishwasher, ice maker, irrigation, or humidifier. Make sure toilets aren’t flushing and softeners aren’t regenerating.
2) Watch the meter.
Find the water meter (street box or basement utility area).
Note the flow indicator (small triangle/star/digital drip). If it’s spinning while everything’s off, there’s flow somewhere.
If the meter is dead still for 60 seconds, your spike may be billing cycle overlap, guests, or irrigation scheduling—still run the toilet/irrigation checks below.
3) House vs. yard test (main shutoff split).
Close the house main shutoff (usually where water enters).
Look at the meter again:
Still moving? Leak is between meter and house (service line, yard, irrigation).
Stopped? Leak is inside the home (toilets, softener, water heater, slab, fixtures).
Now you know which path to chase.
If the Meter Moves With the House Valve Open (Indoor Suspect)
A) Toilets: The #1 silent water waster
Lift tank lids. Listen for hiss or trickle.
Drop food coloring in the tank and wait 10 minutes (don’t flush). Color in the bowl = flapper or valve leak.
Jiggle the handle? That’s a worn lever/chain.
Fix: New flapper/flush valve. If tanks sweat or run often, check the fill valve and overflow tube height.
B) Water heater + relief lines
Look for water at the TPR valve drain line or under the tank.
Warm puddle at the heater base or a dripping relief tube adds up fast.
Fix: Replace faulty TPR, address over-pressure (see PRV below), or replace a failing tank.
C) Angle stops & supply lines
Run a hand around toilet and faucet supplies, laundry hoses, fridge/ice line.
Any coolness, corrosion, or green crust = micro-leak.
Rubber washer hoses? Upgrade to braided stainless.
D) Slab leak clues (pressurized hot/cold under the floor)
Hot spots on tile/laminate, constant water heater cycling, or the meter only moves when hot valve is open.
Faint whooshing in quiet rooms.
Fix: Pro diagnosis with acoustic gear/thermal camera; likely reroute the leaking run above slab or spot repair if accessible.
E) Water softener or filter systems
Stuck brine valve or failed auto-bypass can send water to drain all day.
Listen for trickle at the softener discharge or check the filter housing for seepage.
F) Humidifiers, recirc pumps, and hidden appliances
Whole-home humidifiers tied to furnaces, instant-hot taps, and recirculation pumps can hide leaks inside cabinets or returns.
Look for mineral tracks/salt crust at drain connections.
If the Meter Moves With the House Valve Closed (Outdoor/Yard Suspect)
A) Irrigation system
Turn controller Off. Confirm flow stops; if yes, irrigation is the issue.
Open backflow box: look for seep at test cocks or relief ports, damp soil, or cracked bonnets.
Walk zones for spongy turf, running heads when controller is off, or a broken lateral.
Fix: Repair heads/laterals, service/replace backflow assembly, update schedules.
B) Service line (meter to house)
Meter still spins with house off and irrigation off = service line leak.
Look for greener strip, puddle near walkway, or the sound of running water at the foundation.
Fix: Pressure test and pinpoint with geophones/helium tracer; trenchless replacement if feasible.
Pressure Problems That Cause “Leaks” (and Damage)
High pressure (PRV issues)
Too much pressure forces TPR valves to drip, makes toilet fill valves chatter, and bursts weak hoses.
Check a hose bib with a simple gauge. Target range: ~50–65 psi for most homes.
If you’re high or it swings wildly, your PRV may be failing.
Fix: Adjust or replace PRV, then recheck the heater TPR and fixture valves.
Thermal expansion
Closed systems need an expansion tank on water heaters. If it’s water-logged or absent, the TPR will dump water.
Fix: Test/replace expansion tank, verify charge pressure matches house pressure.
30-Minute Isolation Method (When You’re Stumped)
Turn off supply stops to toilets, softener, fridge, and washer one by one.
After each shutoff, check the meter’s flow indicator.
If it stops, you just isolated the circuit.
If it never stops with all fixtures isolated, suspect slab/service line.
This simple drill saves hours—and often the service call—if a toilet or appliance is the culprit.
What Our Leak-Detection Visit Looks Like (A+ Process)
Interview & meter test – We repeat the meter/valve splits to verify inside vs. outside and hot vs. cold.
Pressure + PRV check – We document static/working pressure and expansion tank condition.
Thermal and acoustic sweep – Thermal imaging for hot-line slab leaks; acoustic listening for pinpointing.
Fixture & appliance audit – Toilets, softeners, filters, humidifiers, fridge lines, and heater relief paths.
Isolate + verify – Valve-by-valve shutoffs with meter confirmation.
Plan & pricing – Spot repairs (flappers/valves), reroutes for slab leaks, service-line options (trenchless where possible).
Documentation – We provide findings for insurance if needed, with photos and pressure readings.
When water is showing up where it shouldn’t—or you can hear flow with everything “off”—we treat it as urgent and prioritize same-day arrival.
Repairs We Can Often Do Same Day
Toilet flappers/fill valves
Angle stops and braided supply lines
Water heater TPR and minor relief-line fixes
Softener/filtration bypass & control head issues
Irrigation backflow component swaps (common parts stocked)
For slab or service-line leaks, we’ll give you reroute vs. repair options and schedule right away.
Prevention That Actually Works (and Pays for Itself)
Annual pressure check + PRV tune
Expansion tank test and replacement when needed
Braided stainless at toilets/washer; ditch rubber hoses
Smart leak sensors under sinks, at the heater, and by the washer
Whole-home shutoff + app (auto-closes on abnormal flow)
Water-heater service (flush/anode check) to prevent TPR nuisance discharges
Irrigation audit each spring; blowout each fall
Quick Reference: 5 Fast Clues
Toilet dye test = color in bowl → fix flapper/valve.
TPR dripping → check PRV/expansion tank or failing heater.
Hot spot on floor + constant heater cycling → likely hot-line slab leak.
Meter spins with house valve off → yard/service line or irrigation.
Irrigation off + meter spins → service line; call for locate/pinpoint.
FAQs
Could a spike be just seasonal irrigation?
Yes—compare controller logs and rainfall. If the meter moves with the house valve closed, irrigation or service line is likely.
Will a slab leak always show water on the floor?
No. Many drain straight into soil. Look for warm zones and constant heater activity.
Can high pressure really cause a big bill?
Absolutely. It drives tiny leaks into constant flows and triggers TPR discharge events you may never see.
How soon can you come out?
We prioritize active, unexplained flow and suspected slab/service-line leaks—same-day whenever possible.
Ready to stop the spike (and the damage)?
If your meter won’t sit still—or you’ve got hot spots, dripping relief lines, or suspicious irrigation behavior—let’s track it down. A+ Drain Cleaning & Plumbing can diagnose, pinpoint, and repair leaks before they get expensive.