Water Leak Week – Switchbot, Sonoff and more…

Not sure why two companies I know, decided to introduce water leark sensors in the middle of summer – but I’m happy to do a quick write-up – as it happens I’ve just recently refitted a hot water tank complete with rather large calcium filter and I’m not 100% sure of my engineering skills so – here goes.

Just about now, Sonoff are releasing their SNZB-05P Zigbee water leak detector and SWV smart water valve – more on those when they arrive.

In the meantime, Switchbot sent me their latest “Switchbot Water Leak Detector”. It’s a small unit with integral beeper and self-test button – handy for a quick test after installing.

There are two stainless prongs at the front and two at the back and a text button at the front. Pressing the button gives off a fairly quiet alert, good for probably a couple of metres – I guess that’s intentional.

Sticking a damp finger across either of the stainless pairs lets off a much louder alert which stops immediately the source of moisture is removed. The unit looks substancial and takes a pair of (supplied) AAA batteries. As this is new I can’t comment on battery life as this would be a combination of standby current and what kind of batteries you use. When the battery is low or damp is detected, their APP will put up a low-battery notification and optionally send an email to a destination of your choice.

The manual is interesting, showing examples of places to position the unit, one example being in front of a toilet. Now, I was about to be sarcastic here when I noted that the unit does have a silicone seal around the base which you remove to change batteries.

Good idea – I can think of several local pub men’s toilets which could make use of this – it seems that significant portions of the male population can’t aim. Other examples included under a pipe bend and in the corner of a room on the floor. Switchbot are claiming 2 years battery life without making recommendations as to which brand of battery to use.

The only problem I initially found with all of this was that the unit seemed as if it was going to communicate by Bluetooth as the manual states you need to have a phone with BT4.2 or later. In my building that would be good for maybe 2 rooms between my phone and the unit – I’ve never had a great deal of luck with Bluetooth and range.

But hold on – later in the manual is a reference to the unit connecting to WiFi. Ok, long-press the test button and sure enough – pairing mode…. OK so the Bluetooth was just to get the pairing running. I turned on the Switchbot APP, hit + and immediately the water leak detector signed up and reported safe….OK I could see that being useful.

It is worth noting that unlike the Switchbot thermometer – this device did not show up in my Home Assistant network. There’s also a reference in the manual about using the detector for DRY detection using the “extended probe” inserted in a fishtank. Well, I didn’t get any kind of extended probe in the box!

The unit measure 78mm by 39mm by 32mm.

And now- the Sonoff SNZB-05P Water Leak Detector

Ok, I’m at a loss initially…here’s what you get in the pack… the main zigbee sensor unit uses a supplied CR2477 battery (I wish designers would stick with CR2032 and other more common batteries – I have no CR2477 batteries here at all – good job one was pre-installed). I’m sure the Sonoff site adequately covers usage with the eWeLink APP but here I’ll just mention installation into Zigbee2MQTT as that is what I use.

Ok, SNZB-05P paired with Zigbee2MQTT. I last updated my Zigbee2MQTT a few days ago – and the response to this unit is “unsupported” – not surprising as it is new – HOWEVER despite that it does accept the unit – see the image below – wet finger acros the two contacts – and I get a response immediately – see ALARM 1 below in the Zigbee1MQTT web UI.

At first glance, let me say this unit is WELL SEALED – the only metal bits being the short gold sensors – I see nothing that would indicate anything other than perfect performance on a wet floor – read the Sonoff information in the link above – they really do go into detail.. knowing where to start – there are so many places in our home that COULD leak.

Thanks to running my Zigbee2/MQTT in Docker on the Raspberry Pi using Antonio Fragola’s Docker setup and shortcuts, updating Zigbee2MQTT is merely a matter of navigating to the DockerIOT/Zigbee2MQTT folder and keying in DUPDATE in a terminal. Seconds later – done. The SNZB-05P entry still says unsupported at this time (not that surprising given the newness of the device) – but still continues to work and respond to ALARM 1 as above.

Sonoff are CLAIMING a 5-year battery life using that CR2477 – I can only hope they are right (clearly not tested for 5 years as it’s a brand new device).

When I checked my Home Assistant devices list, the SNZB-05P has magically appeared with an “automatically generated definition”. Again in Home Assistant, under “entities” it looks like everything is in there – see image below….

and as I sit here, pressing my wet finger on and off the gold contacts – Home Assistant knows all about it (quick click on the “tamper 1” entity reveals all). Good start – I just need a quick Home Assistant automation to DO something with that. As the unit has no audio output, sounding a bell or alerting my phone (or both) seem like sensible options

I’ll leave the extension lead for another time – not seeing the point of a USB-C connector in a damp environment but no doubt I’m missing the point…

See also Antonio Fragola’s comment below about cheap AliExpress-sourced CR2032-based sensors. Now, if I could time travel and confirm the 5-year claim for the Sonoff unit, I would say “you get what you pay for” but I can’t time travel to confirm or otherwise 🙂