Milesight WS303 Mini Leak Detection Sensor: Your First Line of Defense Against Water Leak Damage


Water leak damage is a common issue that can lead to costly repairs and inconvenience. According to the insurance industry, water damage claims are one of the most frequent and expensive types of claims filed by property owners. Often, leaks go unnoticed until it’s too late. However, with the introduction of Milesight WS303 Mini leak detection sensors, property owners can easily monitor potential water leaks in their homes and take actions before any serious damage occurs.



  • Water leakages could go unnoticed until it’s too late, causing significant damage to the property.
  • It is challenging to detect low-level water leakage accurately without false alarms.
  • Installing traditional water leak detection systems is often difficult, time-consuming, and costly.
  • Power failures can also be a cause of concern as they can miss the alarm before the notice of power failure.



TheWS303 Mini Leak Detection Sensor is a compact and powerful device that helps to detect water leaks in homes, offices, libraries, warehouses, etc. The sensor can be easily installed under sinks, near water heaters, washing machines, and other water sources. Milesight WS303 Mini Leak Detection Sensor works by detecting water leaks through its two stainless steel probes. When the probes come into contact with water, they send a signal to the sensor. The sensor also has a built-in buzzer that sounds an alarm. Additionally, Milesight LoRaWAN® gateways and Milesight IoT Cloud can work with the WS303 to provide a complete water leak detection solution. The LoRaWAN® Gateway acts as a bridge between the sensor and the cloud server, enabling secure and reliable data transmission. Once a water leak is detected, it will alarm admins locally and remotely to take prompt action to prevent significant damage.


In addition, the WS303 Mini Leak Detection Sensor can work with the Milesight UC100 IoT Controller to provide additional functionality. The UC100 is an intelligent device that enables remote control of the water valves controller. When a leak is detected by the WS303 Mini Leak Detection Sensor, it will send a signal to the UC100 IoT Controller, which will then shut off the water pipe via a valve controller. This feature adds an extra layer of protection against water damage and ensures that the problem is basically resolved before significant damage occurs.


With this comprehensive solution, users can prevent significant damage caused by water leaks while ensuring the safety and security of their properties and assets.


Why You Need This Product? 

  • Early Detection of Leaks

Milesight WS303 Mini Leak Detection Sensor helps you detect leaks before they cause major damage. Early detection of leaks can save time and money in the long run, as admins can take action to prevent further damage.

  • High Sensitivity

Its high sensitivity enables it to detect a minimum water level of 0.5mm using liquid conductivity.

  • Easy to Use

Milesight WS303 Mini Leak Detection Sensor is easy to install and use. Compact design, 3M tape mounting, and wireless data transmission make it flexible to be mounted on walls or surfaces.

  • Local and Remote Alerts

Milesight WS303 sends alerts to the admin’s smartphone or email, ensuring that the admin receives notifications events. It also has a built-in buzzer that sounds an alarm when a leak is detected, alerting nearby people immediately.

  • Auto Pipe Valve Control

The WS303’s Milesight D2D communication protocol ensures ultra-low latency and direct control without gateways. WS303 can directly send a command to UC100 IoT Controller, which will then shut off the water pipe via a valve controller. It can avoid major damage even if there is no network connection.

  • Long Battery Life

The WS303 is effortless to install and operates on a long-lasting coin cell battery that can last up to five years.



Q: Can Milesight WS303 Mini Leak Detection Sensor detect all types of water leaks?

A: Yes, WS303 detects all types of water leaks, including slow leaks and bursts. Once conductive water connects two probes to form a circuit, it will send out alerts.


Q: Does the Milesight WS303 work with any gateways and cloud platforms?

A: The sensor is designed to work with Milesight’s LoRaWAN® gateways and Milesight IoT Cloud, but it can also work with other LoRaWAN®-compliant gateways and cloud platforms.


Q: What type of liquid can the WS303 detect?

A: WS303 uses liquid conductivity to detect a leak by forming a circuit with two little metal probes. Thus, Milesight WS303 can detect water, vinegar, liquid metal, molten salts, or other types of conductive liquids.


Q: How often do I need to replace the battery?

A: The battery in Milesight WS303 lasts up to 5 years, after which it will need to be replaced.


Q: What is the wireless range of the WS303?

A: The wireless range of the Milesight WS303 Mini Leak Detection Sensor is up to 2 km in urban areas with its LoRaWAN® technology.


Q: How can I choose between sensors of WS303, EM300-SLD, and EM300-ZLD?

A: In general, if you need flexibility in spot leak detection, WS301 may be the best option for you; If you require spot leak detection with an extended probe, EM300-SLD may be a better choice; If you need to detect leaks in a specific zone, EM300-ZLD would be the most suitable sensor.

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