Plumbing · Buying guides · Updated November 2026
Water Leak Detectors: Standalone Alarms vs. Smart Sensors
A leak detector cannot stop a pipe from failing, but it can turn a slow leak into a small cleanup instead of a big repair. The main choice is how you want to be alerted: a beep in the room, an alert on your phone, or a valve that shuts the water off.
Types of leak detectors
| Type | How it alerts you | Good for | Watch for |
|---|---|---|---|
| Standalone alarm | Loud beep when the sensor gets wet | Inexpensive coverage in many spots | Only helps if someone is home to hear it |
| Smart (Wi-Fi) sensor | Phone alert; some also sense temperature | Vacation homes, frequent travelers | Needs Wi-Fi or a hub; check battery life and subscription fees |
| Automatic shutoff valve | Closes the main water line when a leak is detected | Whole-house protection | Usually needs a plumber to install on the main line |
Where to put sensors
- Next to the water heater.
- Behind the washing machine.
- Under the kitchen sink and dishwasher.
- Behind the refrigerator if it has an ice maker or water line.
- Near toilets and under bathroom sinks.
- Next to the HVAC air handler or condensate pump.
- Near the sump pit.
What to check before buying
- Battery type and how you will know when it is low.
- Whether the app has a monthly fee.
- Freeze alerts, if you have pipes in unheated spaces.
- For shutoff valves: your main line size and whether you have a spot to install it.
Some home insurers offer discounts for leak detection systems. Ask yours. For an active leak, see leaking water heater.
Cost figures are national ranges from the sources listed in our plumbing cost guide, not a quote from FixFinch or any contractor. Calls connect you with an independent service provider in our network. FixFinch is not a contractor and does not perform the work.