Does the 3RWS18BZ need a Third Reality hub to work with Edge?

No. Third Reality supports pairing it directly to open Zigbee platforms without its own bridge or hub. It joins the Zigbee radio on an EpiSensor Gateway, and Edge reads it there.

Can the alarm be silenced or shortened?

Yes. The buzzer can be switched off, or the alarm duration set from 1 to 255 minutes. A duration of 0 keeps the siren sounding continuously. Both are writable from Edge.

How long do the batteries last?

Third Reality rates the two AAA alkaline cells for three years. Edge reports the battery level and a low-battery flag, so the cells can be changed before the sensor goes quiet.

Does it still alarm if the network is down?

Yes. The 120 dB siren sounds locally when the sensor detects water, whatever the state of the internet connection. With Edge, the leak is also handled locally on the Gateway.

How is it different from the Third Reality WL2 (3RWS0218Z)?

The WL2 is a separate model. Its Zigbee definition reports the leak and the battery level only, with no buzzer switch or alarm duration. The siren settings on this page belong to the 3RWS18BZ.

Third Reality 3RWS18BZ Zigbee water leak sensor

Compatibility

Compatible with EpiSensor Edge over Zigbee.

Pair it with the Zigbee radio on an EpiSensor Gateway. Edge reads it locally on the Gateway.

Edge reads 7 values from it, listed under Interface.

Connect it with

Gateway ZGW-20
From €899 ex VAT Configure Gateway

Specifications

3RWS18BZ is the Zigbee model identifier of Third Reality’s Smart Water Leak Sensor, named Water Leak Sensor Gen1 in Third Reality’s firmware notes. It sits flat on the floor. When water reaches it, it sounds a 120 dB alarm on the spot and reports the leak over Zigbee. The local alarm does not depend on an internet connection.^1, 3, 5

Power: Battery. Two 1.5 V AAA alkaline cells, supplied. Third Reality rates them for three years.¹
Alarm: 120 dB built-in siren¹
Siren timer: 0 to 255 minutes; 0 is continuous⁴
Batteries: 2 × AAA 1.5 V alkaline, included¹
Battery life: Rated for 3 years¹
Wireless: Zigbee; needs a Zigbee hub or coordinator¹
Mounting: Placed flat on the floor²
Reset: Hold the reset button for 3 seconds²
Firmware: Updated over the air; Gen1 release 1.00.73 of 23 January 2026³

Where it is used

Floors under water heaters, washing machines, sinks and dishwashers in staff kitchens and welfare areas, alongside the building’s water metering.
Water consumption monitoring for commercial buildings
Plant rooms, on the floor near calorifiers, pumps and pipe joints.
Boiler performance monitoring
Serviced apartments and hotel rooms, where the manager needs the alert and a long siren in an occupied room is unwelcome.

Interface

Readings and settings, with units and ranges where Third Reality publishes them. readable, readable and writable.

Download

Reading	Unit	Range or values	Access
Measurements 2
Switch	-	-	Read only
Water leak	-	Binary state	Read only
Controls 1
State	-	Binary state	Read and write
Settings 2
Water leak buzzer	-	Binary state	Read and write
Water leak buzzer alarm mode	min	0 to 255 min	Read and write
Diagnostics 2
Battery low	-	Binary state	Read only
Battery	%	0 to 100 %	Read only

The leak state and the low-battery flag both come from the sensor’s IAS Zone status, as alarm 1 and the battery bit.⁵

The buzzer switch and the alarm duration live in Third Reality’s own cluster, 0xFF01, with manufacturer code 0x1233.⁵

The sensor also carries a standard On/Off cluster, which appears as a switch state. Third Reality does not document a use for it, so leave it out of alarms and dashboards.^2, 5

Setup

Open pairing in Edge
In Edge, open pairing on the Gateway’s Zigbee network. The Gateway accepts new devices while pairing is open.
Fit the batteries
Open the back cover with a screwdriver and fit the batteries. A new sensor goes into pairing mode as soon as it is powered.²
Reset it if it has been paired before
Hold the reset button for 3 seconds. This restores factory settings and puts the sensor back into pairing mode.²
Confirm the join
The sensor flashes and then turns red when it has joined. Check that Edge identifies it as Third Reality 3RWS18BZ.²
Set the siren
Read the water leak buzzer and alarm mode in Edge, and set them for the site: the buzzer off for a silent alert, or an alarm duration in minutes, with 0 for continuous.⁴

Common questions

Does the 3RWS18BZ need a Third Reality hub to work with Edge?: No. Third Reality supports pairing it directly to open Zigbee platforms without its own bridge or hub. It joins the Zigbee radio on an EpiSensor Gateway, and Edge reads it there.^1, 2
Can the alarm be silenced or shortened?: Yes. The buzzer can be switched off, or the alarm duration set from 1 to 255 minutes. A duration of 0 keeps the siren sounding continuously. Both are writable from Edge.^2, 4
How long do the batteries last?: Third Reality rates the two AAA alkaline cells for three years. Edge reports the battery level and a low-battery flag, so the cells can be changed before the sensor goes quiet.^1, 4
Does it still alarm if the network is down?: Yes. The 120 dB siren sounds locally when the sensor detects water, whatever the state of the internet connection. With Edge, the leak is also handled locally on the Gateway.¹
How is it different from the Third Reality WL2 (3RWS0218Z)?: The WL2 is a separate model. Its Zigbee definition reports the leak and the battery level only, with no buzzer switch or alarm duration. The siren settings on this page belong to the 3RWS18BZ.⁵