Meross Smart Water Leak Sensor (MS405) Review: A Great Update at a Great Price

Today I’m reviewing the brand-new Meross Smart Water Leak Sensor (MS405) — and I’m excited to share my thoughts! This is the updated version of Meross’s older leak sensor, which has been around for a few years now (although I never got to try the original).
Meross kindly sent me this sensor to review, but as always, this is a completely honest review.
If you prefer watching, I also have a full video review up on my YouTube channel: Mark’s Tech Vlogs!

Pricing and Value
The kit, which includes the sensor and a new hub (the MSH400), costs around £25 — which is really impressive. Plus, you can save an extra 10% with my discount code marktech10
It’s important to note that the MSH400 hub included in the kit is different from Meross’s MSH450 Matter Hub. The MSH400 supports Alexa, Apple Home, Google Home, and SmartThings — but not Matter. However, you can use this sensor with the MSH450 hub as well (which is actually what I’ve been doing).
The MSH400 hub supports up to 24 devices, while the MSH450 supports up to 32.

Design
Both the hub and sensor have a clean, modern design.
Hub: A small white rounded box with a HomeKit QR code on the side, a LED light on top, and a USB-C port and pairing button on the back.
Sensor: Also white and rounded, with a sleek look you won’t mind tucking under a sink. It has a speaker, LED indicator, sensors on the top and bottom, and rubber feet for stability.
The hub connects via 2.4GHz WiFi, and once you add it to Apple Home, any future devices paired with it will appear automatically.
One tip: if you have an older Meross hub, you’ll need to factory reset your devices to move them to a new hub — they can’t just be ported across. I’ve raised this with Meross in the past.

Features and Specs
Here’s what the MS405 brings to the table:
IP66 water and dust resistance — perfect for leaks and splashes.
Powered by 2 AAA batteries (included), with a battery life of over 3 years.
Notifications when the battery gets low.
Works with Alexa, Google Home, SmartThings, and Apple Home — I’ve been using it with Apple Home exclusively.
Dual 100dB alarms — both the hub and sensor are super loud if they detect water.
Colour-coded alerts in the Meross app.
2 years of historical data logged in the app.
Top and bottom sensors detect everything from slow drips to pipe bursts.
100-meter transmission range from hub to device.
2-year warranty (standard for most Meross products).

Setup
Setting up the sensor was quick and easy:
Plug in the hub and open the Meross app.
Tap the “+” button, select Sensors, and find the leak sensor.
Choose your hub (you may need to add it first if you haven’t already).
Press the pairing button on the hub, then double-press the button on the leak sensor.
Let the app do its thing — name your device, assign it to a room, and you’re done!
If you’ve added the hub to Apple Home, the sensor will show up there automatically too.
A quick tip: In Apple Home, you can find it under Home Settings > Hubs to move it to the right room.
Finally, just place the sensor wherever you want it — under sinks, behind toilets, near water heaters — anywhere leaks might happen. I’ve placed mine under my bathroom sink.

Performance
I’ve been using the Meross Smart Leak Sensor for about two weeks now, and while I thankfully haven’t had any leaks, the sensor and hub have stayed connected and stable the entire time — which is important for peace of mind.
During testing, I poured small amounts of water on the sensor to see how it responds — and it works impressively well.
The dual sirens are loud enough that even if the sensor is tucked away, you’ll definitely hear it.
You’ll get notifications through both the Meross app and Apple Home.
You can even set the Meross app to send critical alerts — so you’ll be notified even if your phone is in Do Not Disturb mode. (Which is exactly what you’d want if there’s a water leak!)

Verdict
Overall, I’m really impressed with the new Meross Smart Water Leak Sensor.
✅ It’s great value considering it includes a hub.
✅ It looks modern and blends in easily.
✅ It’s loud enough to make sure you’re alerted immediately.
✅ And it’s compatible with all the major smart home platforms.
Honestly, I don’t have anything bad to say about it!
If you’re looking for a smart water leak sensor, I highly recommend checking this one out.
You’ll find links below — and if you have any questions, feel free to leave a comment, like the post, or check out my full video review over on Mark’s Tech Vlogs!