"Irrigation Controller" is a term that irrigation and landscape professionals often use when referring to the device (typically a timer) that controls an irrigation system. While traditional controllers simply work on set time schedules, newer technologies allow for "smart" irrigation controllers that make intelligent decisions based on the environment, contributing to water conservation.

According to the Irrigation Association, smart irrigation controllers "reduce overall water usage, typically by 30% or more, saving you money and making a large, positive impact on your community's efforts and water supply."

IRROMETER irrigation control products allow any controller to become a "smart" controller by using our proven IRROMETER or WATERMARK soil moisture sensing technologies. Our devices read the soil moisture before an irrigation and will prevent watering when not required by the plant. Our products can provide significant savings, even over other "smart" irrigation methods.

The graphs to the right display results from studies evaluating the effectiveness of our WATERMARK Electronic Module (WEM).

Select a link below or scroll down for more information about IRROMETER Soil Moisture products for landscape applications.

WATERMARK Electronic Module (WEM) -Soil Moisture Control Device for standard 24VAC controllers

WaterSwitch (WS1) -Single sensor residential design for controllers with sensor terminals.

WATERMARK Electronic Module (WEM-B) -Designed for DC battery powered controllers with sensor terminals

Multiple Hydrozone System (MHS) -System for managing and grouping multiple irrigation zones with up to 8 different sensor locations

IRROMETER TGA -Tensiometer based control system

Landscape Products Brochure
IRROMETER Soil Moisture Basics
IRROMETER Landscape Design Guide

Waterperfect Login:

Login page for IRROMETER Landscape Products Customers /"WaterPerfect Irrometer Portal"

For more Landscape document downloads, please click here

A pdf file of the Boulder, CO test reports can be viewed here.

For additional test results showing the potential water savings possible using IRROMETER products, please click here
For current results of the IWMS ET Demonstration Project, please click below:


Websites relating to soil moisture control of irrigation systems:

EPA Watersense Program
EPA Watersense Efficient Landscaping Guide
HGTV Water Conservation Tips
IA Turf and Landscape Irrigation Best Management Practices
SFWMD Irrigation Overview

Links to Water Conservation Sites: Scheduling Guide
Smart Approved WATERMARK (AU)
California Urban Water Conservation Council
Allience for Water Efficiency
California AB_1881 Water Conservation Bill
US Green Building Council LEED Program


The WATERMARK Electronic Module (WEM) is an electronic unit 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. Solid state electronics and potting ensure the module is maintenance free and long lasting.

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

WEM Features:

  • 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

For further documentation information regarding the WEM, please click here
WEM shown with included WATERMARK Sensors

WEM shown with included WATERMARK Sensors

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.

WaterSwitch Features:

  • Simple to install on new or existing systems
  • Easy to adjust
  • Requires only one sensor
  • 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

For a WaterSwitch installation video please click here

For further documentation information regarding the WS1, please click here

WaterSwitch with included WATERMARK Sensor

WaterSwitch with included WATERMARK Sensor

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 Specification Document
WEM-B Installation and Operating Instructions

For further documentation information regarding the WEM-B, please click here

WEM-B with included WATERMARK sensors

Battery WEM connected to battery powered controller

Battery WEM connected to battery powered controller

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.

MHS Installation and Operating Instructions
MHS Specification Sheet
WaterGraph 3.3 Software Download for MHS/W-MHS Systems
WaterGraph 3.3 Software for MHS/W-MHS Systems Instructions

MHS system, shown in wired configuration
MHS system

The IRROMETER Model TGA tensiometer is specifically designed for applications such as parks, golf courses, cemeteries, freeways & dividers, athletic fields, and industrial landscaping. Our Model TGA is aligned horizontally to allow for measuring irrigation in the shallow root zone of turf and landscaping, while also incorporating the IRROMETER Adjustable Moisture Level Selector & Switch feature. This feature allows for setting a desired point on the gauge at which a switch will be closed for automatic irrigation. The Adjustable Moisture Level Selector & Switch can be compared to a thermostat, continually measuring the soil moisture and signaling the controller whenever a water application is desirable, or preventing an application when there is no need for one. TGA IRROMETER

TGA Specification Document

For further documentation information regarding the TGA, please click here

The following tests show results that are typical of the savings users can achieve using our soil moisture based technology to make controllers "Smart". Our systems work "from the ground up" to provide the most accurate and cost effective control over landscape irrigation.

The results are generated using our WSMK, which is a kit that is retro-fitted into an existing landscape irrigation system. The kit consists of two irrigation valve box lids that replace similar ones in the existing system. One of these lids is fitted with the WATERMARK Electronic Module soil moisture control device that wires to the valve. This device limits this specific valve so it can only deliver water when the soil moisture has been sufficiently depleted. Both lids are fitted with 24 volt AC cumulative hour meters, wired to the valves, that record the actual time that the valves have been delivering water.

To demonstrate water savings, two irrigation zones of a system are chosen with similar plant material on identical scheduling programs from the controller, and then the kit is installed. A simple comparison of the accumulated hours of applied irrigation from the hour meters demonstrates the savings realized through the use of the soil moisture control device. Actual savings from numerous test sites are documented below.

IRROMETER Company, Inc. | Phone: 951-682-9505 | Fax: 951-682-9501 | |

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