Programming Controllers: Avoiding Water-Wasting Runoff -The Benefits of the "Run/Soak" Function on "Smart" Controllers

By Gene Johnson, Technical Services Manager, Weathermatic Inc.

Modules like this supplemental decoder (below right) snap into existing controllers (top) and increase or even double the capacity. With this Underhill unit, all stations, or only selected stations, can be converted to two-wire operation. Two-wire technology has proven a cost-saving alternative on sites such as sports fields, cemeteries, HOA common areas, parks and schools.

Recently I viewed a manufacturer's web site that showed dollar bills floating down a "river" of curbside water. The purpose of the illustration was to remind us that the irrigation industry has the responsibility to provide efficient systems that protect landscapes, save money and conserve water.

The two major reasons for runoff are sloped terrain and hard, compact soils. In these situations, irrigation water ends up in the street or may just evaporate from puddles that are formed. Other causes of runoff are improper system design and installation or lax system maintenance. We've all seen sprinklers overspraying driveways and sidewalks, or broken and mis-aligned heads sending water down the gutter or, worse, eroding slopes and landscapes.

Poorly calibrated irrigation controllers are a leading cause of unintended runoff from turfgrass areas onto sidewalks or parking lots (as seen here). In areas with water rationing ordinances, visible runoff like this can result in citations and fines.

Today's Smart Controllers

Today, economical "smart" systems are a major proactive step for the industry. They use weather-based data to modify zone watering times on a daily basis and they limit overwatering, the primary cause of runoff.

Irrigation designers and contractors recognize that the answer to the problem of runoff is to use a zone watering schedule that allows for "soak in" time. This is often called "run/soak" or "cycle soaking" the landscape. The term "run" or "cycle" refers to how long you can run a zone before runoff begins. "Soaking" refers to the amount of time it takes for water to percolate or move into the soil.

Auto-Soak Advantage

Sounds simple enough. In fact, large commercial and golf course irrigation controllers have offered users "run/soak" features for many years. At the homeowner system levels different scenarios apply.

Additionally, most residential controllers water by program and have a limited number of start times to use. Ideally, runoff calculations need to be done for each zone, not just by program.

Here is a sample calculation of "run and soak" times for two different zones on a system utilizing spray head irrigation: View full Size Image

Calculation of "run/soak" times is just too complicated and time consuming for most homeowners. Also, watering "blackouts" mandated by many municipalities limit the number of hours available for watering and this can further complicate the use of "run/soak." It becomes almost an impossible scheduling task unless you have a controller that allows for "pause and resume" after watering blackout periods. Fortunately, some controllers now on market do have this capability.

"Today's ???smart controllers' have easy-to-program ???run/soak' and ???omit' pause functions to comply with the proliferation of local ordinances and water requirements," said Brodie Bruner, vice president of marketing at Weathermatic, an irrigation equipment manufacturer.

" With a ???smart controller,' I just enter the soil type and slope and the controller does the rest."??" Dan Andrus

"As irrigation manufacturers we have to do more than just apply the correct amount of water. We also have to also provide a method of eliminating wasteful runoff, such as offering ???run/soak' options," he said.

Many "smart controllers" on the market provide a method of run and soak watering. However, most have not been within the budget for the average homeowner. This is starting to change as some of the models now available can accommodate an 8-zone system for less than $350 retail.

Calsense's ET2000 is among the next-generation controllers that lets superintendents run multiple soak cycles. The unit is programmable by time, ET, and/or soil moisture with direct moisture sensing. Soak watering, 12-month programming, and interactive monthly volume budgets are among the features available with the state-of-the-art controller.

Put to Test

Dan Andrus, owner of All American Landscapes in La Crescenta, Calif., says: "I install ???smart controllers' for all of my clients. They like the idea of being more environmentally-responsible and saving on water costs. An automatic ???run/soak' feature works alongside an auto adjust ET-based watering schedule.

Note: "Smart irrigation" controllers with "run/soak" features include: Weathermatic's SmartLine, RainMaster's Eagle, Rain Bird's ET Manager, Hunter's ET System and Calsense's ET2000 (below).