Where should water leak sensors be placed?
On the floor at the lowest point next to each thing that can leak: the water heater, the washing machine, under kitchen and bathroom sinks, beside the sump pit, and below any pipe run that could freeze. Water follows the floor, so a sensor an inch uphill of the low spot can stay dry while the puddle grows.
Start with the highest-consequence spots
Water heater: in the drain pan if there is one, otherwise on the floor at the base.
Washing machine and dishwasher: behind or beside the appliance near the supply hoses.
Under sinks: at the back of the cabinet floor, below the supply valves and trap.
Sump pit and floor drains: a sensor just above the normal high-water line tells you the pump has failed.
Add the freeze-prone runs
A pipe that splits while frozen leaks when it thaws, often hours after the cold alert. Put a leak contact on the floor below pipes in the garage, crawlspace, or along exterior walls so the thaw does not go unnoticed.
Mounting
The contacts must touch the floor, flat, at the low point. Pour a cup of water nearby once to see where it runs, and test the sensor with a damp cloth when you install it.
ProbeHarbor treats a wet leak sensor as an alert on every plan, with no rule to set up.
Frequently asked questions
How many leak sensors does a house need?
One per water source you would not notice quickly. For most homes that is four to six: water heater, washer, kitchen sink, a bathroom or two, and the sump or lowest floor drain.
Can a leak sensor shut the water off?
A sensor alone only alerts. Shutting off the water takes a motorized valve on the main line that an automation or webhook triggers when the sensor gets wet.
Related
Get a freeze alert for your space
ProbeHarbor watches probes in garages, crawlspaces, and cabins and alerts you before pipes freeze. The free plan includes email alerts; bring an ESP32 probe or connect Home Assistant.