About Us

The IRROMETER Company has been in business since 1951, manufacturing soil moisture measuring, controlling, and sampling instruments used worldwide for scheduling irrigation. Principal brand names are IRROMETER (Tensiometer) and WATERMARK (electrical resistance granular matrix sensor). These soil water potential/tension measuring instruments originated in the early part of the 20th Century, and were used by soil and plant scientists to measure soil water status in their experiments.

The IRROMETER Company was the first to produce commercially viable versions of this technology, and although this technology is scientific instrumentation, the instruments are inexpensive and easy to use for all irrigation applications. The use of soil moisture based irrigation scheduling has been proven an efficient way to deliver irrigation water for agriculture, nursery/greenhouse and landscape/urban irrigation. Further, the instrumentation can be used for controlling (automatic irrigation systems) and signaling (for data logging systems and inputs to weather stations).


The IRROMETER Company was founded in Riverside, CA in 1951. While at the Citrus Experiment Station at the University of California Riverside in the late 1940's, inventor Tom Prosser witnessed crude, homemade tensiometers in use and immediately saw the potential for farmers to use these instruments as tools for scheduling irrigation. Prosser set about designing user friendly, robust versions of these homemade instruments which could be economically manufactured for sale, and in 1951 the IRROMETER (or "irrigation meter") was born, fulfilling Prosser's vision of a commercially available Tensiometer.

In 1953, Sheldon Pooley, the son of a local citrus grower who was one of Prosser's first customers, joined the Company as its Sales Manager and began the growth of The IRROMETER Company worldwide. In the late 1980's, the Company expanded its product line with the addition of the WATERMARK soil moisture sensor which it acquired from its inventor, Glenn Larson. The low cost and reliable technology of the WATERMARK sensor has made a major impact on the large scale use of soil moisture measurement technology by production agriculture throughout the world.

With the development of electronic interfaces for automated irrigation systems used in landscape irrigation, the use of WATERMARK sensor technology now has become a "SMART" irrigation system technology. Water purveyors and the EPA are embracing the concept of "SMART" irrigation systems as a means to prevent the overuse of water in landscape irrigation. Coupled with the WATERMARK Monitor data-logger, the use of radio telemetry systems and Internet technologies bring IRROMETER and WATERMARK sensors in to the 21st Century. Irrigators managing millions of acres throughout the world now have the power of knowing both when and how much to irrigate with precision.

From the early 1950s, when Shel Pooley cruised the dusty farm roads of California and Arizona in a Nash Rambler stocked with IRROMETERs, to the computer equipped irrigation manager of today, both IRROMETER and WATERMARK sensors are standard management tools being used to Optimize Irrigation, Worldwide. Ask us today how we can help you join this ever growing irrigation management team and help make irrigation a more sustainable and profitable practice.