Aqara Water Leak Sensor
A coin-sized, battery-powered Zigbee leak sensor for under sinks and behind washing machines - but it needs an Aqara hub before it can alert you.
Strengths
- Completely installation-free - a battery puck you place on the floor, ideal in a rented flat
- Very sensitive detection with near-instant alerting when water touches the contacts
- IP67 housing survives actually being flooded
Watch outs
- Requires an Aqara hub before it can do anything - it is not a standalone Wi-Fi device
- On third-party Zigbee setups (ZHA/Zigbee2MQTT) users report drop-offs and re-routing quirks that can need manual fixing
- Coin-cell battery rather than easily-swapped AAs
- Model SJCGQ11LM
- Protocol Zigbee
- Hub required Yes - an Aqara Zigbee hub (or an existing Zigbee2MQTT/ZHA setup for advanced users)
- Battery CR2032 coin cell
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What does the Aqara leak sensor actually detect?
Water reaching the two contact pads on its underside. The Amazon product listing puts the detection threshold at roughly 0.5 mm of water on the base, which is a shallow enough film that the sensor triggers well before a leak becomes a visible pool. Detection is a simple conductive bridge rather than a moisture-level reading, so it answers one question - is there water here - very quickly and reliably.
What it does not do is sense humidity, drips that miss it, or a leak inside a wall. It is a floor-level tripwire, and its usefulness depends almost entirely on placement. A sensor two feet from where the water actually arrives will report nothing at all while a cupboard floods.
Why does a renter want leak sensors at all?
Because the downside is asymmetric and the upside is cheap. A slow leak under a sink or behind a washing machine can run for days before anything is visible, and by then the damage is to flooring, plaster and whatever was stored nearby. In a rented flat the argument over who pays is rarely simple, and it is far easier to have caught the leak in hour one.
These sensors are small and cheap enough to deploy several around a home, which is the right way to use them - one under the kitchen sink, one behind the washing machine, one by the boiler or hot water tank. Damp from a leak is a different problem from damp caused by condensation; if your issue is misting windows and black spotting rather than an actual leak, our guide to stopping damp and condensation is the more relevant read.
What does hub required really cost you?
More than people expect, and it is the single most important thing to understand before buying. This is a Zigbee device with no Wi-Fi radio, so it cannot reach your router or your phone by itself. On its own it is inert - it will detect water and have no way to tell you.
You therefore need an Aqara Zigbee hub, which is a separate purchase, a mains socket and another box to site. Once that hub exists the economics invert nicely, because each additional sensor is very cheap and the hub is a one-off, so a whole-flat deployment costs little more than a two-sensor one. But the first sensor carries the full cost of the system. If you only want one sensor and own no Aqara kit, a standalone Wi-Fi leak alarm is very likely the better buy.
Where should you put them?
At the lowest point where water would actually collect, not simply near the appliance. Under the kitchen sink, put it beneath the trap rather than at the cupboard entrance. Behind a washing machine or dishwasher, it wants to be on the floor at the back where the hose connections are, which usually means sliding the appliance out once.
Also consider the boiler, the hot water cylinder if there is one, and any radiator with a valve that has previously wept. The IP67 rating matters here: the housing is sealed to survive immersion, so a sensor that ends up sitting in standing water keeps working rather than dying at the moment you need it. Since there is nothing to fix in place, you can move them freely as you learn where your flat's weak points are.
How does it hold up on third-party Zigbee?
This is where reported experience diverges from the marketing. On Aqara's own hub, behaviour is what you would expect. On third-party Zigbee setups such as Home Assistant's ZHA or Zigbee2MQTT, users report drop-offs and re-routing quirks that can need manual intervention - the sensor falls off the mesh, or attaches to a router node that then misbehaves.
It is worth knowing that the wet alert itself is the fast, reliable part. What owners more often report as slow is the dry-state reset and the secondary readings, which can lag well behind the instant notification that water has arrived. For an alarm that is an acceptable trade: you want the alert immediate and you can tolerate waiting for the all-clear. If you are running a third-party Zigbee network, budget some setup patience rather than expecting plug-and-play.
Does the Aqara Water Leak Sensor work without a hub?
How much water does it take to trigger it?
Can it survive being flooded?
How long does the battery last?
Where is the best place to put a leak sensor?
- Model
- SJCGQ11LM
- Protocol
- Zigbee
- Hub required
- Yes - an Aqara Zigbee hub (or an existing Zigbee2MQTT/ZHA setup for advanced users)
- Battery
- CR2032 coin cell
- Dimensions
- 50 x 50 x 15 mm
- Water resistance
- IP67-rated housing (per the Amazon product listing)
- Detection threshold
- Water reaching approx 0.5 mm on the base contact pads (per the Amazon product listing)
- Operating temperature
- -10 to +55 C
- Operating humidity
- 0 - 100% RH
- Ecosystems
- Aqara Home app; Apple Home via a compatible Aqara hub
- Subscription
- None