David Butcher: Intelligent, Automatic, Internet Enabled X10 Controlled Water Saving Sprinklers

After years of watching other folks' lawn sprinklers watering before, during and after rain storms, and having to remember to enable the "Rain Delay" on my own sprinklers to save water, I finally combined my computer, an X10 controlled outlet, an X10 Firecracker Serial Port controller, a TM751 wireless receiver, a standard 6 zone sprinkler / irrigation controller, the national Weather Service, and a small program I wrote to create an "intelligent" sprinkler system that waters more when it's hot, and skips watering when it rains. Here is how it all fits together:

First, the theory:

  1. The sprinkler / irrigation control must be able to "remember" the watering program with power off.
  2. The watering program must be programmed to water the maximum amount you ever need, and it must be set to water every day.
  3. The sprinkler / irrigation control must be plugged into an X10 controlled outlet - I use an SR227 Wall outlet.
  4. The outlet must be ultimately controlled by a computer. It may be controlled by X10 hardware, but the computer must have the ultimate control.
  5. The computer must be turned ON at least once a day.
  6. The computer must be connected to the Internet.
  7. The computer must be programmable - there must be a way to control the outlet with a program, unlike 99.9% of the software available today, which requires a Human Being at all times to drive it. I use a shell script on my computer, which is running Linux. You will have to find your own solution - and there are many, many possible solutions.
  8. The computer must check the local weather, and then decide whether to turn the outlet off or on for the next watering cycle.
  9. The computer must turn the outlet on frequently enough in mild weather to water adequately, but not water every day. I "default" to watering Monday, Wednesday and Friday when weather is mild.
  10. The system must be reasonably "failsafe." The way I put this system together, there is no chance that an X10 control that sticks "on" (yes, it happens sometimes) will result in an expensive water bill. Yes, there is a chance that the watering will stop if the computer crashes, for example, but that will not cause problems as fast as a watering system that will not turn off.

And after that, you will never again have your sprinklers running during the rain, or running too little during hot weather. Every day, the computer will check the local weather, and if rain is forecast, the outlet will be switched off. If the forecasted temperatures are warm enough, the outlet will be switched on every day, and watering will occur every day. If the weather is mild, the watering system waters in a set pattern, but not every day.

I have had this system set up for a year, and the landscape has never looked better, while our water bills are half what they used to be.

The web page you are reading is being served from an old AMD K6-III 300MHZ (similar to a Pentium) computer. Since this Web site is always available, this computer is on all the time. Lucky me. If your computer is not on all the time, you can still automate your watering system, but you will have to start the computer up to check with the National Weather service to do it. I would bet that most of you readers run your computer every day, and if not, you run them almost every day. Fine - with the right software and possibly some additional X10 hardware, you can use this solution.

The three ingredients you must concoct:

Put the three together and you are home free.

Would you like more details? Here they are:

Does it work? Indeed it does! Here is a snapshot of the log file:

THU High temp: 79 did water
FRI High temp: 86 did water
SAT High temp: 94 did water
SUN High temp: 96 did water
MON High temp: 83 did water
TUE High temp: 79 did water
WED High temp: 79 did water
THU High temp: 77 did not water
FRI High temp: 81 did water
SAT High temp: 86 did water
The "default" is to only water Monday, Wednesday and Friday. As you can see it was hot when I copied the log and the system was "aware" of it, and it was watering more frequently.

It took a while to get everything assembled and "tuned." If you decide to try the same thing, I hope this page saves you some time. Good luck!

If you are interested in saving water in other ways, check out my home-made Do-It-Yourself Toilet Tank Top Sink Water Saver.

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