Express News Weekly Article
Saturday, April 23, 2005
By Calvin Finch, Conservation Director, SAWS, and Horticulturist

Ordinance Requires Rain Sensors

            The Water Conservation Ordinance that passed on January 20, 2005, has a provision that requires all in-ground irrigation systems with a controller must have a rain sensor by January 1, 2006.  A rain sensor detects rain and stops the irrigation system from operating until conditions are drier.  If you do not have one and your system irrigates during a rainstorm, you can receive a misdemeanor citation.   

 

            Rain sensors are inexpensive and relatively easy to add to your system.  The sensor itself is under $50.00.  If an irrigation contractor supplies it and connects it for you the cost ranges from $115.00 to $150.00.  SAWS’ customers may receive a rebate of 50% of the cost or $50.00, whichever is less.  To receive the rebate, you must select a sensor with the wafer/hygroscopic disk technology.  Karen Guz, SAWS Conservation Planner, has assembled the following Question & Answers to address the most common questions about rain sensors.  Check the SAWS website:  www.saws.org click ‘Conservation’, click ‘2005 Conservation Ordinance’, and then click ‘Rain Sensors’ for more information.    

 

How does the rain sensor work?

 

The most effective types of rain sensors have absorbent disks inside them that swell when they are wet.  The swelling interrupts power flow that would normally open a valve and start an irrigation cycle.  When the disks dry out, the power is allowed to flow the next time the controller sends a signal.

 

Will rain sensors stop irrigation immediately as rain begins?

 

No. Rain sensors must absorb enough water to swell the disks and cut off the electric signal. Just as it can take awhile for the ground to absorb water during a fast rain, it takes a little while for the disk to absorb water.  However, if it has been raining for any length of time or has been wet for many days, the rain sensor should keep the system from running.

 

What kind of rain sensor should I buy?

 

The best rain sensors have hygroscopic disks inside. The hygroscopic disk rain sensor is the only type available for rebate to SAWS customers through December 30, 2005. There are so many models and brands it would be impossible to list them all.  Ask questions about products and any warranty they may include.  Also consider if you want a product that allows you to bypass the rain sensor for a maintenance check during a wet period.  If you want an easier installation, there are wireless types that allow you to install the electrical interrupter right at the controller inside your garage and then the part that responds to rain outside where it will be exposed to weather conditions.  Of course these extra features come with increased cost.  We recommend that you visit an irrigation supplier and take with you the brand and model number of your irrigation controller.  The staff at the store can then show you different options and explain features and installation requirements.

 

Are the rain sensors difficult to install?

 

That depends on how comfortable you are with wiring, electricity, and digging.  The most economical models of rain sensors must be installed on the wires that supply electricity to all of the valves of your irrigation system.  These wires run alongside the main pipes that supply water to the valves of the system.  It is important to locate the rain sensor where it will interrupt power to all of the valves and not just some of them.  Wireless brands of rain sensors can be simpler to install because they have two parts.  One part is installed at the controller to the power wires (no digging) and one part is installed outside where it will be exposed to the rain. 

 

If you think you will have difficulty with installation, consider hiring an irrigation professional.  Ask questions about the product being used and request a test after installation is complete.  Make sure you can access the rain sensor device for future maintenance or testing.  Placing it high in a tree will create challenges in the future.

 

Will you be inspecting homes to check for rain sensors?  How will you enforce this rule?

 

            Citizens often alert us when they observe water waste, such as irrigation during rain or water running down the street.  Our enforcement process for all water waste includes a courtesy education visit to the site with an official warning to the homeowner or site manager.  When we hear that a site is watering during a rain or immediately after a big rain, we will visit the site to determine if a rain sensor is in place and if it works.  If the homeowner or manager has not complied with the requirement to put in a functional rain sensor, then he or she will be placed on the water waster list until the rain sensor is installed or repaired.  Being on the water waster list means that any additional violations of any water waste could result in the issue of a ticket.