Where to Put Water Leak Sensors in Your Home

The best answer to where to put water leak sensors is this: beside every appliance and fixture that holds or uses water, at the lowest point of the floor where a leak would run first. Start with the washing machine, the water heater, the dishwasher, the fridge water line, under each sink and next to the sump pit. A typical house needs six to ten sensors to cover the places where leaks commonly begin.

Where to put water leak sensors first

If you are buying a few at a time, cover the highest-risk locations before the rest. These are the spots with pressurized hoses, tanks that eventually fail, or water that runs when nobody is watching.

1. Washing machine. Place the sensor on the floor behind or beside the machine, near the supply hoses and drain. If the machine sits in a drain pan, put the sensor inside the pan.
2. Water heater. Set it on the floor at the base of the tank, or in the pan if there is one. Tanks usually fail by leaking from the bottom.
3. Dishwasher. Slide the sensor under the unit through the toe-kick space, or place it in the cabinet beside it where the supply and drain lines run.
4. Fridge with an ice maker or water dispenser. Put it on the floor behind the fridge near the water line connection. This thin line is easy to kink or loosen when the fridge is pushed back.
5. Kitchen sink cabinet. Set it on the cabinet floor under the trap and supply valves. Leaks here can drip for weeks behind the cleaning supplies.
6. Sump pit. Mount a sensor or its probe just below the rim of the pit so it alarms when the water rises above its normal level, which tells you the pump has stopped keeping up.

Other places worth covering

• Bathroom vanities, under the trap and shutoff valves.
• Beside each toilet, at the back near the supply line and tank connection.
• The furnace area, near the air conditioner condensate drain, any condensate pump and a furnace-mounted humidifier.
• The water softener or filtration system, if you have one.
• Where the main water line enters the basement, near the meter and main shutoff.
• Near the basement floor drain, to catch water backing up or running toward it from somewhere else.
• Under a boiler or along a radiant heating manifold.
• Below a window or along a wall where you have seen seepage before.

The spots people forget

Upstairs plumbing matters most because the water has further to fall. A second-floor laundry, an ensuite or a tub over a finished ceiling should each have a sensor. If a bathtub or shower has an access panel behind it, put a sensor inside on the subfloor. Also think about anything added after the house was built: a basement bar sink, a bidet seat, a reverse osmosis filter under the kitchen sink, a fridge in the garage. Add-on connections are often the weakest ones.

How to place a leak sensor so it works

• Put it at the low spot. Floors are rarely level. Pour a little water and watch which way it runs, or use a marble, then place the sensor in that path.
• Keep the metal contacts flat on the floor. A sensor sitting on a hose, a ridge of flooring or a mat will not get wet until the leak is large.
• Use a sensor with a cable or rope probe for tight or wide areas. The rope detects water anywhere along its length, which suits the space behind a row of laundry machines or along a basement wall.
• Leave it where you can reach it. You need to test it and change the battery.
• Avoid placing it where normal splashes happen, such as right in front of a shower door, or you will learn to ignore the alarm.
• Label each sensor in the app by its exact location so an alert tells you where to go.

Which kind of sensor to buy

A basic standalone sensor sounds a loud alarm and costs around $15 to $25. It only helps if someone is home to hear it. A Wi-Fi or hub-connected sensor sends an alert to your phone, which is the better choice for basements, mechanical rooms and any house that sits empty during the day. Some sensors can also trigger an automatic shutoff valve on the main line, so the water stops even when nobody responds to the alert.

Check the wireless signal before you commit. Basement mechanical rooms are often the weakest spot in the house for Wi-Fi. Test a sensor in place before you buy ten of them.

Testing and upkeep

Test every sensor twice a year. Touch a damp cloth across the contacts and confirm the alarm sounds and the alert reaches your phone. Replace batteries on a set schedule, and wipe dust off the contacts while you are there. After any alarm, dry the sensor completely and put it back in the same spot.

To get started, walk through the house with a notepad and list every fixture and appliance connected to water, floor by floor. That list is your sensor count. Buy for the top six first and fill in the rest over time.

Common questions