Best smart sensors in water alarms and leak sensors
Four long-range leak sensors and a hub that send app alerts and a low-temperature warning, with a sounder on each sensor that works even when the internet is down.
Our score: 7.8/10 out of 10Researched, not lab-tested
- Connection
- Long-range radio to a hub
- Battery
- 2 × AAA per sensor
- Warranty
- 2 years
- Water resistance
- IP66
Is it right for you?
Pros
- Hub plus four leak sensors in one kit
- App alerts through the hub, plus a sounder on each sensor
- Freeze warning at a temperature you set in the app
- Pairs directly with YoLink valve controllers, no internet needed
- IP66 sensors on two AAA batteries; 2-year warranty
Cons
- Needs the YoLink hub and internet for phone alerts
- Rated for 32 to 122 °F only, so not for unheated spaces in winter
- Alarm loudness not stated by YoLink
- Rechargeable and zinc batteries are ruled out
- Best for
- Watching several spots at once (sump, water heater, washer, under sinks) and getting phone alerts away from home.
- Not for
- Unheated garages or crawl spaces that drop below freezing, or homes without reliable internet.
Our verdict
For alerts away from home, this is the kit we’d start with. YoLink pairs a hub with four Water Leak Sensor 4 units (YS7906-UC), which talk to the hub over YoLink’s long-range radio rather than your Wi-Fi; the hub then sends alerts to the YoLink app. Each sensor also has a sounder you can switch on in the app, so it beeps on the spot even if the internet is down.
The guide describes electrodes on top and bottom, so a sensor catches a drip from above as well as water on the floor, and a freeze warning at a temperature you choose. The sensors are IP66 and rated for 32 to 122 °F, so they belong in heated space. They can also pair directly with a YoLink valve controller, such as the Valve Controller 2 with Bulldog, to shut off the water with no internet involved. YoLink’s store sells the kit in Canada and the US.
Setting it up
Each sensor runs on two AAA batteries, already fitted. When they run low the sensor blinks red quickly; replace them with new alkaline or lithium AAA cells, never rechargeable or zinc, don’t mix old and new, and test the sensor afterwards. Four beeps mean a freeze warning and two beeps mean water. Place sensors where leaks start: beside the sump pit, under the water heater, behind the washer and under sinks.
Safety: A leak alert near the furnace, panel or washer is not a reason to rush in. If the basement is already flooded, stay out of the water while anything electrical could be live and ask your electric utility to cut the power; our guide to the first hours after a basement floods goes step by step.
Specs
YoLink Water Leak Sensor 4 Starter Kit (Hub + 4 Sensors)
Alerts
| Connection | Long-range radio to a hub |
|---|---|
| Phone alerts | Yes |
| Shuts off the water | No |
| Freeze alert | Yes |
| Hub needed | Yes |
| Alarm | Yes |
| Water resistance | IP66 |
| Sensors in the box | 4 |
Other details
| Battery | 2 × AAA per sensor |
|---|---|
| Warranty | 2 years |
Maker’s figures, checked 4 Nov 2026.
YoLink Water Leak Sensor 4 kit questions
Do YoLink leak sensors need Wi-Fi?
The sensors don’t use Wi-Fi; they reach a YoLink hub over long-range radio, and the hub connects to the internet for app alerts.
Can YoLink sensors warn about freezing pipes?
Yes. The sensor gives a freeze warning, four beeps plus an app alert, at a temperature you set. It is rated down to 32 °F itself, so keep it in heated space near the pipes you’re watching.
Can a leak sensor shut off my water?
Yes, with a YoLink valve controller. The sensor can pair directly with it (YoLink calls this Control-D2D), so the valve closes even if the internet is down.