Smart Multifunctional Flood Sensor MEROSS MS420

The smart multi-function flood sensor MEROSS MS420 helps protect your home from the consequences of water leaks, rainwater flooding and frozen pipes. Thanks to the large electrode surface, adjustable probe height and additional 1.5-meter cable, it can also monitor hard-to-reach places - such as the space under the washing machine or around pipes - and the water level in tanks. The sensor emits an audible alarm with a volume of 100 dB and allows you to set the conditions under which the alarm will be triggered. The device has a water and dust resistance level of IP65, and thanks to energy-efficient Bluetooth connectivity, it can operate on a single battery for up to 4 years.

Accurate water detection and adjustable probe height

The large electrode surface area allows for the detection of even small amounts of water, allowing for quick detection of minor leaks. The adjustable probe height allows you to adapt the detection method to the surrounding conditions. At a low setting, the sensor reacts to small amounts of water, while a higher setting helps prevent false alarms caused by temporary surface moisture. The device can also detect a lack of contact with water, so it can monitor the water level in aquariums, tanks or animal feeders and alert you when the level drops.

Additional probe for hard-to-reach places

The included 1.5-meter probe cable allows you to extend the monitoring area without having to place the entire sensor in a place where there is a risk of flooding. The small probe also fits into narrow gaps, for example under a washing machine or dishwasher, near pipes and drains or behind furniture. This allows you to monitor areas where leaks could go unnoticed for a long time. The included adhesive tape makes it easy to attach an additional probe to the desired location.

Smart notifications and fewer false alarms

The sensor detects leaks, monitors precipitation and warns of the risk of freezing. It also allows you to combine different conditions – such as the presence of water and low temperatures – so that the alarm is triggered only in certain situations. The ability to set a detection delay reduces the number of false alerts caused by short-circuits with water. In the event of a threat, the device activates a loud alarm, allowing you to respond faster and limit potential damage.

Durable design and up to 4 years of operation

The IP65 housing protects the device from dust and water jets, making the sensor suitable for areas exposed to moisture. The operating temperature range of -20 °C to 60 °C allows for use in a variety of conditions. Bluetooth Low Energy (BLE) technology reduces power consumption, and the replaceable CR123A battery provides up to 4 years of operation. The device is compatible with smartphones with Android 8.0 or later and iOS 13 or later.

Included in the package

• MEROSS MS420 Smart Flood Sensor
• Cable with additional probe
• CR123A battery
• Battery compartment opening tool
• User manual

It is important to know

The key to choosing one is that it matches your specific goal: detecting water leaks. Wi-Fi and hub-less operation make it easy to get started, but they don't in themselves guarantee compatibility with every smart home platform.

• If you want to connect it to existing devices or automations, check support for your ecosystem before purchasing; a Wi-Fi connection doesn't guarantee that devices will connect to each other.
• For a larger system, it makes sense to think in advance about how the sensor will fit into the broader design, rather than assuming compatibility based solely on the connection method.

Source of editorial recommendations: ENAA guides and team experience.

In practice

💧 Water leak detection in the kitchen or bathroom

🟢 Very suitable - it is a dedicated water leak sensor, so it makes sense to monitor rooms where you are concerned about leaks.

🏠 The first step to a smart home

🟢 Very convenient - it does not require a central unit to use, so you can start with one sensor without first setting up a system with a central unit.

Answers to frequently asked questions

Do I need a control panel to use it?

No, this sensor does not require a control panel.

Description updated: November 2026

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