Soil Moisture Control Device for standard 24VAC controllers.

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Designed for DC battery powered controllers.

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Residential design for 24VAC controllers.

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System for managing multiple zones with different sensors.

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WATERMARK Electronic Module

The WATERMARK Electronic Module (WEM) is designed to control valves based on soil moisture requirements. Adjustable to plant requirements from 10 to 120 Centibars, the WEM uses input from WATERMARK Soil Moisture sensors to control individual valves, valve groups, or all valves. Irrigation controllers equipped with WATERMARK Electronic Modules control irrigation based on measured soil moisture, rather than the theoretical assumptions made by a climate based controller. The WEM includes a manual override and works with all 24 VAC controllers.

Also available in a "dry Contact Tech Support: " output version to signal sensor circuits or relays, version WEM-DC-T.


  • Control your irrigation costs
  • Save water, labor, and energy
  • Deliver water only when and where necessary)
  • Grow healthier turf and plants
  • Mitigate pest and disease problems
  • Reduce fertilizer leaching
  • Protect groundwater by minimizing runoff
  • No more re-programing controllers for seasonal changes
WEM Specification Document
WEM DC-T Specification Document

WEM Installation and Operating Instructions
WEM DC-T Installation and Operating Instructions

Additional Documentation

WATERMARK Electronic Module- Battery Version

The Battery WEM is designed for use with battery powered DC controllers that have a sensor circuit, functioning similarly to our standard WEM used with AC controllers.

Whenever a controller powers a valve, the WEM will either allow or prevent the irrigation based on soil moisture conditions. If the soil moisture is wetter than the setting selected on the WEM dial, an irrigation will be prevented. If the soil moisture is drier than the setting, the irrigation will be allowed.

Depending on the controller being used, either a closed or open switch position will be required to allow irrigation. The Battery WEM can be wired to accommodate either controller requirement, by selecting the appropriate switch connection wire pair.

WEM-B SpecificationDocument
WEM-B Installation and Operating Instructions

Additional Documentation


Designed for home owners and using the proven WATERMARK sensor, this simple device "controls the controller" so that watering is only allowed when necessary based on soil moisture status. One sensor and an adjustment range designed specifically for turf grass make this an affordable and simple way to make any controller with "sensor" terminals a Smart controller.

  • Simple to install on new or existing systems
  • Easy to adjust
  • Only allows watering if the sensing area actually requires water
  • Four selectable moisture levels cover the range required for turf grass
  • No need to re-program controllers for different seasons
  • Pays for itself in water savings
WS1 Specification Document
WS1 Installation and Operating Instructions
Installation Video

Additional Documentation

Multiple Hydrozone System (MHS)

With large commercial landscapes, the variety of watering demands is often too diverse to be adequately judged by a single sensor location. For such applications, this control product provides the flexibility to independently control any number of valves- watering plants with similar watering demands ("Hydrozones")- separately. Up to eight independent moisture zones can be created per 24VAC controller, to control up to 48 station valves.

This product is available in two versions: a "wired" version with up to 8 sensors wired to the MHS unit, and a "wireless" version using 2.4GHz solar powered radio nodes to transmit soil moisture readings to the MHS unit.

Our Landscape Design Guide demonstrates how all the WATERMARK soil moisture control products can be specified when designing systems. Suggested detailed drawings are available for the professional designer on our download page.