The cheapest insurance in the house, provided you put them where a leak would actually start — not where it's convenient.
A water leak detector is a small puck with two metal probes on the underside that completes an electrical circuit the moment water bridges them. It is one of the cheapest, most reliable smart-home devices there is — there is no ambiguity in the sensor reading the way there sometimes is with motion or presence detection, and false positives are rare because water is water.
The entire value of the category lives or dies on placement, not on which brand you buy. A sensor left in a drawer catches nothing. The right spots are: directly under a washing machine and dishwasher's water connections, behind a toilet, under a water heater, at the lowest point of a basement floor, and next to any exposed pipe joint that has ever needed a repair before.
The more capable end of the category pairs a leak sensor with a motorised shutoff valve on the mains water line, so a detected leak doesn't just send a phone notification — it closes the water supply automatically, which is the difference between a puddle and a flooded floor while you're at work.
What to look for
Probe vs extension cable/rope
A basic sensor detects water directly under its own probes, a few centimetres of coverage. Some models add a cable extension (a "rope" sensor) that can be routed around the base of a water heater or along a pipe run for wider coverage from one unit.
Battery life and low-battery alerts
Most leak sensors sip power and last one to three years on a coin cell, since they only draw meaningfully when triggered. Confirm the app surfaces a low-battery warning with enough lead time — a dead leak sensor is a false sense of security, worse than no sensor at all.
Pairing with a shutoff valve
The most effective setups link a leak sensor's alarm to a motorised ball valve on the mains supply, so the water shuts off automatically rather than just sending a notification you might not see in time. Confirm your valve and sensor are from the same ecosystem or that your hub can bridge the automation.
Local protocol vs Wi-Fi
Zigbee and Z-Wave sensors report through your hub and keep working during an internet outage for local automations (like triggering a shutoff valve). Wi-Fi-only sensors depend on your router and, for phone alerts, the manufacturer's cloud being up during exactly the kind of event — a flood near electronics — that can take a network down.
Sound and light alarms on the unit itself
A local siren or flashing light on the sensor itself is a useful backup for anyone in the house who isn't checking a phone, and matters most in a basement or utility room where notifications are easy to miss.
IP rating if placed somewhere genuinely wet
Most leak sensors are only splash-resistant, not submersible. If it might actually sit in standing water rather than just detecting the first trickle, check the IP rating explicitly rather than assuming.
The shortlist compared
Brand
Model
Protocol
Extension cable
Alarm on unit
Indicative price
Aqara
Water Leak Sensor
Zigbee
No
Yes, 100dB
€15
Fibaro
Flood Sensor
Z-Wave
Yes, sold separately
Yes
€45
Aeotec
Water Sensor 7
Z-Wave / Zigbee (dual)
No
Yes
€40
Eve
Water Guard
Matter over Thread
Yes, bundled
Yes, 100dB
€80
SONOFF
SNZB-05
Zigbee
No
No (app only)
€12
D-Link
Water Sensor
Wi-Fi
No
Yes
€35
Prices move constantly and vary by country, so we give an indicative band
rather than a figure that would be stale within a month. Check the brand's own store for the
current price.
The picks in detail
Aqara Water Leak Sensor
Zigbee
The default recommendation for a Zigbee household: cheap enough to buy five or six and scatter under every appliance, with a loud onboard alarm and reliable low-battery reporting through Aqara's own hub or any Zigbee hub that supports the device.
It has no cable extension option, so coverage is limited to directly under the unit — fine for an appliance connection, less useful for ringing the full base of a water heater.
Very cheap, easy to buy several
Loud 100dB onboard alarm
Reliable Zigbee reporting to any compatible hub
No cable extension for wider coverage
Coin-cell battery, no mains-powered option
Fibaro Flood Sensor
Z-Wave
Fibaro's sensor is the pick for Z-Wave households, and its optional cable extension — sold separately — lets one unit ring the full perimeter of a water heater or boiler rather than just the spot directly underneath, at the cost of an extra purchase.
It also reports temperature alongside leak status, useful for a frozen-pipe warning in an unheated utility room during winter.
Optional cable extension gives wider coverage from one unit
Also reports temperature, useful for frost warnings
Solid Z-Wave range and reliability
Cable extension is a separate purchase
Pricier than the Zigbee equivalents
Aeotec Water Sensor 7
Z-Wave / Zigbee (dual)
Aeotec's dual-protocol design means the same physical sensor works on either a Z-Wave or Zigbee network depending on a setting, useful for a household that hasn't committed fully to one protocol or is migrating between hubs.
It's a straightforward probe sensor without a cable extension option, so treat it as a direct-placement unit rather than a wide-coverage one.
Works as either Z-Wave or Zigbee, useful during a hub migration
Reliable, well-reviewed build quality
Reasonable price for a dual-protocol device
No cable extension option
Setup requires picking the protocol correctly at pairing
Eve Water Guard
Matter over Thread
Eve's entry is the Matter/Thread pick, meaning it pairs directly into Apple Home, Google Home or any Matter controller without a proprietary hub, and it bundles a cable extension as standard rather than as an accessory.
It's also the most expensive sensor in this comparison, and Thread requires a border router on your network (many recent smart speakers and hubs include one) to get the local, low-latency benefit.
Matter over Thread, no proprietary hub needed
Cable extension included, not a separate purchase
Loud onboard alarm plus phone alerts
Most expensive sensor here
Needs a Thread border router on the network for full benefit
SONOFF SNZB-05
Zigbee
SONOFF's sensor is the cheapest usable option in this category by a wide margin, aimed at anyone who wants leak detection under every sink and appliance in the house without the bill adding up. It reports reliably to a Zigbee hub and that's essentially the entire feature set.
There's no onboard siren, so it depends entirely on your hub or phone surfacing the alert — fine if you already trust your automation setup, less reassuring as a standalone device in, say, a rental property for a tenant who may not have the app.
Cheapest reliable option here
Small, unobtrusive body
Good Zigbee range for the price
No onboard alarm, notification-only
Coin-cell battery with no cable extension
D-Link Water Sensor
Wi-Fi
D-Link's sensor is a straightforward Wi-Fi option for a household without a Zigbee or Z-Wave hub at all — it just needs a Wi-Fi network and the D-Link app, with no bridge or hub purchase required.
As with any Wi-Fi sensor, it depends on your router and D-Link's cloud service being reachable at the exact moment a leak might also be threatening nearby electronics, which is the structural weak point of this whole protocol choice for this specific use case.
No hub required, works on Wi-Fi alone
Onboard alarm included
Simple app setup
Depends on Wi-Fi and cloud connectivity during exactly the event it's meant to catch
Battery life shorter than Zigbee/Z-Wave equivalents
Under the washing machine and dishwasher's water connections, behind the toilet, under and around the water heater, at the lowest point of a basement or utility room floor, and next to any pipe joint that has needed a repair before. Placement matters far more than which brand you buy.
Can a leak sensor turn off my water automatically?
Only if paired with a separate motorised shutoff valve on the mains supply, triggered by an automation rule in your hub when the sensor alarms. The sensor alone only detects and notifies; it has no physical connection to your plumbing.
How long do the batteries last?
Typically one to three years, since the sensor only draws meaningful power the moment it detects water and sends an alert. Confirm your chosen model surfaces a clear low-battery warning well ahead of time, since a dead sensor gives false confidence.
Do I need a cable extension?
Only if you want one sensor to cover a wider area than directly beneath it — typically around the full base of a water heater or along an exposed pipe run. For a single appliance connection, a basic probe sensor placed correctly is enough.
What's the difference between Zigbee/Z-Wave and Wi-Fi versions?
Zigbee and Z-Wave sensors report through your hub and can trigger local automations (like closing a shutoff valve) without needing the internet. Wi-Fi sensors need your router and usually the manufacturer's cloud service to deliver a phone alert, which is a weaker link during the kind of event — flooding near electronics — this category exists to catch.
Terms explained
Probe sensor
A leak detector with two exposed metal contacts on its underside that complete a circuit when bridged by water, triggering the alarm.
Rope/cable extension
An accessory cable, sometimes sold separately, that extends a leak sensor's detection perimeter around a wider area such as the base of a water heater.
Shutoff valve
A motorised ball valve fitted to the mains water line that can close automatically on command from an automation, physically stopping a leak rather than just reporting it.
Thread border router
A device (often built into a smart speaker or hub) that bridges a Thread mesh network to your Wi-Fi router, required for Thread devices to reach the internet and other networks.
