LoRaWAN® Water Leak Sensor

WS303
Mini Water Leak Sensor

WS303 is a compact, wireless water leak sensor that triggers instant alerts upon leak detection and supports D2D automatic response, helping prevent water damage, ideal for smart homes, museums, and other design-sensitive spaces.

Get in Touch Watch the Video
  • FEATURES
  • MODELS
  • DOWNLOAD
  • Home
  • IoT LoRaWAN® Series
  • WS303

Instant Detection, Enduring Performance

Reliable Leak Detection

D2D & LoRaWAN® Connectivity

Long Battery Life

Compact & Durable Design

high sensitivity detection
immediate alerts

High-Sensitivity Detection Down to 0.5 mm

WS303 LoRaWAN® water leak sensor detects even minimal water presence as low as 0.5 mm. By leveraging water conductivity, it forms a circuit between two metal probes to instantly identify leaks.

Immediate Alerts with Local & Remote Notifications

WS303 will trigger an immediate audible alarm and sends a remote notification when a leak is detected. The built-in buzzer can be enabled or disabled, and can be stopped automatically when the leak clears or via a downlink command.

d2d enabled automatic valve shutoff
lorawan wireless transmission

D2D-Enabled Automatic Valve Shutoff for Damage Prevention

When a leak is detected, WS303 can instantly trigger a connected controller via Milesight D2D communication for automatic valve shutoff, helping prevent costly water damage. Powered by LoRa®, Milesight D2D enables direct communication between Milesight LoRaWAN® devices without a LoRaWAN® gateway, delivering lower latency and secure transmission.

Learn More about Milesight D2D Communication

LoRaWAN® Wireless Transmission with Long Range

Stable long-range wireless communication up to 2 km in urban areas and 15 km in rural areas.

up to 5 years operation
power failure alarm

Up to 5 Years Operation

Powered by a long-lasting coin cell battery, WS303 delivers up to 5 years of continuous operation.

Power Failure Alarm

Built-in capacitor storage enables a power failure alarm, ensuring uninterrupted LoRaWAN® leak detection even during unexpected outages.

compact aesthetic design
ip67 protection
corrosion resistant structure

Compact & Aesthetic Design

The mini and elegant design allows seamless integration into various environments while fitting easily into space-limited areas.

IP67 Protection

The IP67-rated enclosure ensures stable performance in wet and dusty environments.

Corrosion-Resistant Structure

Gold-plated probes and stainless steel screws prevent corrosion for long-term reliability.

LoRaWAN® Leak Detection across Wide Scenarios

In many critical environments, even a small water leak can lead to costly damage. In the U.S. alone, there were 1.2 million water damage insurance claims in 2022, and commercial water damage losses average $50,000.

WS303 LoRaWAN® water leak sensor delivers reliable leak detection to prevent costly damage across various environments:

Server Room / Data Center Water Leak Detection

Immediate local and remote alarm enables prompt intervention, protecting critical IT infrastructure from unexpected leaks, minimizing downtime, and preventing IT system disruptions.
Learn How WS303 Protects Server Room in Action

Water Leak Detection for Smart Restroom

With IP67 protection and a corrosion-resistant design, WS303 LoRaWAN® water leak sensor operates reliably in humid and harsh restroom environments, ensuring stable leak detection over time, helping facility managers respond before damage spreads.
Explore Milesight Smart Restroom Solution

Laboratory Leak Detection

Featuring 0.5 mm high-sensitivity detection and a compact mini size, WS303 enables precise and discreet installation near sensitive instruments and samples, ensuring early warning without interference.

Leak Detection for Libraries & Archive Room

WS303 LoRaWAN® water leak sensor offers low-maintenance, long battery life operation, making it ideal for protecting valuable documents and humidity-sensitive archives with continuous monitoring.

Water Leak Detection for Cold Storage

WS303 supports continuous monitoring with low power consumption and long battery life. The timely leak alerts help reduce potential losses caused by unnoticed water accumulation.

server room data center water leak detection
water leak detection for smart restroom
laboratory leak detection
leak detection for libraries archive rooms
water leak detection for cold storage

Water Leak Detection Made Simple

Flexible Installation

The compact design enables both
surface placement and wall mounting via
3M tape for quick deployment.

Download Installation Guide

One-Tap NFC Configuration

Quickly switch on/off and configure
the device via the Milesight ToolBox
App using NFC.

broad platform compatibility

Broad Platform Compatibility & Easy Payload Decoding

WS303 LoRaWAN® water leak sensor supports seamless integration with mainstream LoRaWAN® platforms including ChirpStack, The Things Network (TTN), and AWS IoT through a LoRaWAN® gateway. A standard payload decoder is provided to easily interpret battery level and leakage status, enabling quick and seamless integration.

Learn More about Milesight Playload Decoder →

Related Product

em300 sld zld 2

EM300-SLD/ZLD Leak Detection Sensor

EM300-SLD/ZLD
Leak Detection Sensor

EM300-SLD/ZLD

Leak Detection Sensor

  • Trigger Condition: Once Liquid Level Reaches 5mm / 1.5mm
  • Trigger Media: Dual Metal Probes / Rope
  • Detection Range: Spot Detection / Zone Detection
  • Typical Applications: Laboratories, Archives, Communication Base Stations, Warehouses, Server Rooms, Equipment Cabinets, Cold Chain Logistics, Shopping Malls, Workshops
em300 mld 2

EM300-MLD

EM300-MLD
Membrane Leak Detection Sensor

EM300-MLD

Membrane Leak Detection Sensor

  • Trigger Condition: When the Sensing Film
    Contact Conductive Liquid
  • Trigger Media: Customizable Leakage-Detecting Film
  • Detection Range: Zone
  • Typical Applications: Residential Environment, Construction Industry

Related Resources

Success Stories

Solution

Blog

iot smart building lab in spain

Transforming Monolitic's Building Into a More Efficient Office with People Sensing Driven IoT Solutions

Success Story
Learn More
iot digital energy comfort management croatian health resort

Digital Energy and Comfort Management in a Croatian Health Resort

Success Story
Learn More
milesight smart green building for enhanced energy efficiency

Put the "Smart" in Milesight Headquarters

Success Story
Learn More
smart restroom

Smart Restroom Solution

Solution
Learn More
water management in building

Water Management inBuilding Solution

Solution
Learn More
mini leak detection sensor defense against water leak damage

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

Blog
Learn More
water leak detection zone spot sensor

Identify Water Leak Problems in Time Using Zone/Spot Leak Detection Sensor

Blog
Learn More

FAQs

What liquids can a LoRaWAN® water leak sensor detect?

WS303 uses liquid conductivity to detect a leak by forming a circuit with two metal probes, so it can detect water, vinegar, liquid metal, molten salts, or other types of conductive liquids, covering most leak detection needs across residential, commercial, and public spaces.

How does WS303 LoRaWAN® water leak sensor enable automatic valve shutoff via D2D linkage?

When WS303 detects a leak, it transmits the leak signal via Milesight D2D communication to a UC300 or UC100 IoT controller. The controller then triggers valve shutoff through an RS485 interface to prevent water damage. Without relying on a LoRaWAN® gateway, this direct communication delivers lower latency, faster response, and secure data transmission.

Where is water leak detection monitoring most needed?

Water leak detection monitoring is especially important in leak-prone environments, such as bathrooms and cold chain facilities, as well as in humidity-sensitive areas like server rooms, libraries and laboratories, where even minor leaks may cause equipment damage, asset loss, or operational disruption. Featuring a compact design and two flexible wireless installation options, the WS303 can be directly placed on flat surfaces or fixed with 3M tape, making it suitable for a wide range of leak detection needs, even in space-constrained environments.

Specifications

Wireless Transmission
TechnologyLoRaWAN®, Milesight D2D
AntennaInternal Antenna
FrequencyCN470/IN865/RU864/EU868/US915/AU915/KR920/AS923-1&2&3&4
Tx Power16dBm(868 MHz)/20dBm(915 MHz)/19dBm(470 MHz)
Sensitivity-137dBm @300bps
ModeOTAA/ABP Class A
Leakage Detection
Liquid TypeConductive Liquid
Trigger ConditionOnce Liquid Level Reaches 0.5mm
Others
BuzzerSupport
ConfigurationMobile App via NFC or Downlink
Advanced FeatureMilesight D2D Controller, Water Leakage Alarm
Physical Characteristics
Power Supply1 × 590mAh CR2450 Lithium Battery
Battery Life*Around 5.7 years (One hour leakage per week, 25°C)
Operating Temperature-10°C to +60°C
Relative Humidity0% to 100% (Non-condensing)
Ingress ProtectionIP67
Dimension63 × 63 × 14 mm
Weight36.4g (Battery included), 29.8g (Battery excluded)
Material & ColorABS+PC, White
Installation3M Tape Mounting, Desktop
Approvals
RegulatoryCE, FCC
EnvironmentalRoHS

* Tested under laboratory conditions and for guideline purposes only.

Documents

WS303 Datasheet WS303 User Guide Water Leakage Detection Sensor Installation Guide Payload Decoder

Get in Touch about
Your Next Project

  • End User
  • Installer
  • Reseller
  • System Integrator
  • Distributor
  • Consultant
  • Managed Service Provider
  • Video Surveillance
  • Road Traffic
  • Parking
  • Smart Buildings
  • Smart Retail
  • Industrial Routers
  • Other IoT Solutions
Verify Code

If you are interested in Milesight, please leave us a message.

Verify Code

Contact Us

Contact Us

Verify Code

Contact Us to Get More Information