Rain Sensors Help Protect Our River and Lagoon

On a walk through neighborhoods between periods of heavy rain, have you ever seen sprinklers running unnecessarily? During our rainy summers, the sight is pretty common, especially in the early mornings. All the extra water can contribute to flooding. The water can also flow across yards, driveways, and sidewalks, picking up nonpoint source pollutants (e.g., pet waste, fertilizer, etc.) along the way. Water and pollutants then flow out of sight into storm drains, making the problem easy to dismiss. However, our storm drains, canals, ditches, and other stormwater drainage systems eventually lead to the waterbodies we treasure, like the St. Lucie River and Indian River Lagoon.

Rain sensors can prevent unnecessary pollution and conserve waterSprinklers watering lawn while area is flooded due to heavy rains.

Unnecessarily watering our landscapes during times of abundant rainfall harms our environment and our quality of life by wasting water and polluting our natural waterbodies. Installing rain sensors on automatic irrigation systems is one good way to stop unnecessary irrigation. Rain sensors detect when a certain amount of rain has fallen and send a signal to the irrigation system, telling it to hold off on watering. By not irrigating when the extra water isn’t needed, we save water and prevent further pollution.


How much water can be saved using a rain sensor?

Dr. Michael Dukes and Dr. Dorota Haman of UF offer the following example of potential rain sensor water savings:

As an example, if a system irrigates 1/2 acre of turf and is set to run each zone so that 1/2 inch of water is applied per cycle, one can calculate that 13,576 gallons are being applied over the 1/2 acre of turf per cycle. Assuming water costs $2.00/thousand gallons, the savings will be $27.15 every time the sensor eliminates an irrigation event. Even more importantly, 13,576 gallons that would be lost to deep percolation or runoff will be saved. If this amount is multiplied by the number of substantial rainfalls that occur in the area over one growing season, a significant amount of money and water can be saved. 

Source: https://edis.ifas.ufl.edu/ae221
The state of Florida requires rain sensors or similar technologies

The importance of rain sensors and similar technologies was recognized by the Florida legislature and made a requirement for all automatic landscape irrigation systems. Florida Statute 373.62 requires that “Any person who purchases and installs an automatic landscape irrigation system must properly install, maintain, and operate technology that inhibits or interrupts operation of the system during periods of sufficient moisture.” Rain sensors are available wherever irrigation supplies are sold, and they can be installed by a homeowner or an irrigation professional.

Sensor installation and maintenance are key

Sensors must be properly installed and maintained to function well. During installation, consider the location and the sensor settings. Sometimes people mistakenly install rain sensors underneath building overhangs or other obstructions, where they will not be able to sense any rain events. Rain sensors must be installed in areas where they will receive any rainfall that occurs.

When setting up a rain sensor, UF recommends using the smallest set point possible. Most devices will have a lowest setting of 1/8 inch, which will result in the greatest water savings. In any case, set points of more than 1/4 inch should not be used.

Next, the sensor must be connected to the irrigation controller. Some rain sensors can be connected wirelessly, while others are wired into the control box.

Lastly, sensors do require maintenance and must be tested periodically. Sensor maintenance can be as simple as removing debris or vegetation interfering with sensor function. Sensor function can be tested during normal rainfall events, using a method described by UF researchers, Dr. Michael Dukes and Dr. Dorota Haman, in their publication “Residential Irrigation System Rainfall Shutoff Devices, or Rain Sensors.”

County irrigation professional checks the function of a rain sensor.
A Martin County irrigation professional checks the function of a rain sensor on county property.

Whenever a licensed contractor installs or performs work on an automatic landscape irrigation system, they are required to test for the correct operation of each rain sensor or other type of irrigation shutoff device (Florida Statute 373.62). If they find the required devices are not installed or not in operating condition, the contractor must install new devices or repair the existing ones before completing other work on the system.

According to research conducted by Dr. Bernard Cardenas-Lailhacar and Dr. Michael Dukes, in areas where water costs exceed $2.00 per thousand gallons, rain sensor costs were recovered in less than a year. The other benefits of rain sensors, in limiting pollution and conserving water, while not as easy to measure, contribute to our quality of life and enjoyment of our rivers and estuary.


Posted: July 28, 2020

Category: Conservation, Florida-Friendly Landscaping, Home Landscapes, Home Management, Horticulture, NATURAL RESOURCES, UF/IFAS Extension, Water
Tags: Commercial Horticulture Digest, Conservation, Environment, Green Industry, Indian River, Irrigation, Martin County, Rain Sensor, UF/IFAS Extension, Water


Nelson Merchan-Cely
March 2, 2021

Muy interesante la exposicion del problema. Seria maravilloso presentar la forma en que ese problema se solucionaria. Los lideres de cada comunidad pueden ayudar muchisimo a promover la vinculacion al Seguro de Salud. Dada la importancia del trabajador agricola con mayor razon motivarlos para que participen en su promocion. Dios les bendiga. Nelson Merchan-Cely Presidente, Hispanics in Action, Inc.

Carl Frost
August 26, 2020

Next blog post on Florida farms send me a link and I'll share on our farm Facebook page.

Barbara McAdam
July 29, 2020

Very timely blog! Many of us noted irrigation systems running on our way into work last week during heavy rain. The irrigation systems were in shopping centers with large parking lots which can easily flood and the irrigation contributed to larger areas being flooded out and not available for parking. New design recommendations for large expanses of parking areas is much needed and UF/IFAS/Extension has information that can be developed to provide concise details and examples for codes to be developed. something to work on as flooding and drought events are becoming more common.

Kim Bentz

July 29, 2019

Hello Janet, The next Master Gardener Training will be January 2020. You may contact the coordinator, Jennifer Pelham, 772-288-5654 for more information. We look forward to adding another member to our Master Gardener Family. Best regards, Kim

Yvette Goodiel

November 20, 2018

Hi Ruth, Our 2019 tree giveaway will be held on Saturday, January 19th. Please keep checking our website and Facebook for more information. You may also contact our new Master Gardener Coordinator and County Extension Director, Jennifer Pelham, at 772-288-5654. Yvette

Ruth Fox
November 18, 2018

, RuthYvette: Will you be having a seedling giveaway in 2019? Do you have a calendar of events for 2019? Thank You Ruth

Carl Frost
July 15, 2018

Welcome to the 4H neighborhood Natalie!

Kim Bentz

July 10, 2018

Hello Janet, The Master Gardener Program in Martin County will begin the application process this Fall 2018 with an early 2019 class start. Please contact our office at 772-288-5654 for more information. We look forward to hearing from you soon.

Janet Raider
June 29, 2018

Will you be offering a Master Gardener class anytime soon? I was a Master Gardener in Fayette County, KY, and am interested in taking the course in Martin County.

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