How do you maintain water leak sensors?
Updated August 2026
Leak sensors need a quarterly test and little else: dampen the probes, confirm the alert lands on your phone, and, if you have a smart shutoff valve, watch it actually close the water. Swap the batteries once a year even though they are rated for 1 to 3 years, because a sensor with a dead cell fails silent, and a silent sensor is worse than none. Put pucks (about $15 to $40 each) at the highest-risk spots: the water heater, the washer, under sinks, the dishwasher, and the sump pit. A whole-home auto-shutoff runs $150 to $500 installed. See the test interval and how they work.
| Task | Interval | Effort |
|---|---|---|
| Touch the probes with a wet finger or damp cloth | Quarterly | 5 min · DIY |
| Confirm the alert reaches your phone and any hub | Quarterly | 5 min · DIY |
| Trigger the auto-shutoff valve and watch it close | Quarterly | 5 min · DIY |
| Task | Interval | Effort |
|---|---|---|
| Replace the coin or AAA battery in each sensor | Yearly | $2–6 each |
| Reposition sensors that drifted from the drip zone | Yearly | 5 min · DIY |
| Check for corrosion on the contact probes | Yearly | 5 min · DIY |
| Task | Interval | Effort |
|---|---|---|
| Replace sensors with dead or swollen batteries | 1–3 years | $15–40 each |
| Service or replace the motorized shutoff valve | As needed | $150–500 pro |
What neglect costs
A leak sensor earns its keep on exactly one day, and a dead battery makes that day identical to not owning one. Water damage is among the most common and expensive home insurance claims, and a slow supply-line drip behind a wall or under a floor can run into five figures before you smell it. That is the entire case for the quarterly test: a $20 puck that pings your phone at the first drop, or a smart shutoff that closes the main, turns a $10,000 to $30,000 gut job into a mop and a towel. Fresh batteries are $2 to $6 a sensor. The skip-it cost is the whole flood.
Leave these to a pro
The sensors themselves are pure DIY, peel-and-place pucks you test with a wet finger. The pro line is the automatic shutoff valve: a whole-home unit that clamps onto the main and closes it on an alert costs $150 to $500 for the device and typically $150 to $300 more for a plumber to fit it on the supply line. Some insurers knock 5 to 10% off premiums once one is installed, so it can partly pay for itself. Annual battery swaps, repositioning, and the quarterly test never need a service visit.
This whole checklist ships as reminders in OnOtto: every task above, on the right schedule for your home, snooze-proof.
Load this checklist as remindersFrequently asked questions
Where should I put water leak sensors first?
Start where a failure floods the house fastest and hides longest: the water heater base, behind or under the clothes washer, under the kitchen and bathroom sinks, at the dishwasher, near the sump pit, and by any second-floor plumbing. Toilets and the refrigerator ice line are close behind. Set the puck flat on the floor at the lowest point, where water would first pool. A handful of $15 to $40 sensors covers the spots that generate most water claims.
What is the difference between a sensor and an auto-shutoff?
A basic sensor detects water and sounds an alarm or pings your phone, but someone still has to run over and turn the valve. An automatic shutoff adds a motorized valve on the main (or flow monitoring at the meter) that closes the water by itself the moment a leak is detected, even while you are away. Sensors are $15 to $40; a whole-home auto-shutoff is $150 to $500 plus install, and it is the upgrade that actually prevents the flood instead of just reporting it.
How do I test a leak sensor?
Bridge the two metal probes with a wet fingertip, a damp paper towel, or a few drops of water, and the sensor should alarm within a second or two. Then confirm the alert actually reaches wherever you expect it: the on-device buzzer, the hub, and the phone app. If you have an auto-shutoff, run the full test and watch the valve close. Do this quarterly, and re-seat any sensor that has been nudged up off the floor.
How long do the batteries last?
Most leak-sensor batteries are rated 1 to 3 years, but heat, humidity, and frequent alerts shorten that, so swap them yearly rather than waiting for a low-battery warning you might miss. Many models chirp or flag the app when a cell is dying; do not ignore it, because a dead sensor fails silently. Coin cells and AAAs run $2 to $6 apiece. When you change batteries, wipe any corrosion off the contact probes so detection stays reliable.