If water starts leaking, this system turns off the unit's water by itself in about 10 seconds.
How it works
1. A sensor feels waterSmall sensors sit on the floor by every sink, toilet and appliance.
2. Power is cutA small box in the closet turns off the power that holds the valves open.
3. Three valves closeCold, hot and hot-water return shut in 6–8 seconds, and a phone alert goes out.
Cost, installed
Leak Defense quote$12,000
This system$1,600–$3,100
About $8,900 to $10,400 less.
Parts are about $590; the rest is the plumber’s labor.
Ask of the Board
Does this solution satisfy the deductible-waiving conditions afforded to Leak Defense installations?
Like Leak Defense, it shuts off the unit's water automatically, sends a phone alert, and the valves would be installed by a licensed plumber.
What happens if…
A leak startsWATER OFFin about 10 seconds, plus a phone alert
The leak is fixedWATER ONone tap on the phone reopens the valves
The power goes outWATER OFFback on when power returns (or by hand)
The internet goes downWATER ONnothing changes; only phone alerts pause
The equipment breaksWATER OFFit fails safe
Safe by design: the valves need power to stay open, so any failure shuts the water off rather than leaving it running. Each valve also has a hand lever, like the current shut-off valves, so manual operation capabilities are preserved with this solution.
The details
Prices checked at the sellers’ websites on September 30, 2026. Tap a part name to see it at the seller.
Parts and prices
Automatic shut-off valves$192.993 × $64.33U.S. Solid 1″ stainless steel, with hand lever. Drinking-water safe (NSF/ANSI/CAN 61), lead-free. Opens in 6–8 seconds, closes itself when power is cut; 80,000+ cycles.
Controller$24.991 × $24.99Shelly 1 Gen4, a matchbox-sized smart switch. WiFi, Zigbee and Apple Home. 3-year warranty.
Leak sensors$319.928 × $39.99Shelly Flood Gen4. About 2 years on 4 AA batteries, loud alarm plus phone alert, 6.5-ft sensing cable. One by each toilet, under each sink, dishwasher, washer, water heater / HVAC closet, and at the valves.
Power adapter~$1212-volt, 3-amp, like a laptop charger. Plugs into the existing closet outlet.
Wire and small parts~$3250 ft low-voltage wire, lever wire connectors, small junction box.
Normal: power flows, valves open. Leak: controller cuts power, valves spring closed. Power failure: valves close, then reopen when power returns or by hand lever.
What the plumber does
Installs the 3 owner-supplied valves: after the unit's cold-water shut-off, after its hot-water shut-off, and before the shut-off on the hot-water return serving the unit.
Runs thin low-voltage wire from each valve to a small box by the closet outlet. Doorbell-class wiring; no conduit.
Wires the valves to the controller and power adapter.
Tests: with power on, all 3 open; cut power, all 3 close within 6–8 seconds.
After first power-up, the valves need about one minute of power before auto-close will work (manufacturer requirement).
Owner setup after install (about 15 minutes)
Add the controller to the Shelly phone app and switch it on. Valves open.
Add each sensor and name it by location (“Kitchen Sink”).
Create one rule on the sensors themselves (a local “action,” not an app scene): if water is detected, turn the controller off. It then works without internet.
Set the controller to turn back on after a power outage, and turn on phone alerts.
Test: touch a damp cloth to a sensor. Valves close within about 10 seconds. Tap the controller on to reopen.