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:

• The sprinkler / irrigation control, set to water every day. This unit must be plugged into the outlet the computer is controlling.
• A flexible control program that checks the weather and turns the outlet on or off depending on your requirements.
• A computer to execute the program, contact the Weather Service, interpret the results, and "decide" whether to have the outlet on or off that day. If the computer does not run for a day, the worst that can happen is watering or not watering that day. WARNING: if the outlet is off and the computer remains off, watering will stop! Don't trust this system 100% - YOU are still responsible for monitoring how well it is working.

Put the three together and you are home free.

Would you like more details? Here they are:

• The sprinkler / irrigation control is an Orbit Model No. 57161-WT2X (6 Stations) purchased at Orchard Supply Hardware. This compact unit is perfect - its "brain" is NOT powered by the 24 volt transformer. It is 100% powered by two AA batteries. The unit can be unplugged (or as we need, plugged into an unpowered outlet) indefinitely. The 24 volt transformer only needs to be powered during the actual watering cycles. Note that my watering cycle lasts 15 minutes, and the computer keeps the outlet off the rest of the day, saving a measured 70 Watt-hours/day, or 25.5 KWH/Year. I live in California, and yes, we care about things like that.
• The sprinkler / irrigation control is plugged directly into the X10 SR227 outlet. Note that only one "half" of the outlet is controlled (one of the two sockets). Testing the sprinklers or overriding the automation is easy - just plug the transformer into the other socket. It's always on.
• The outlet is controlled by the computer. In my case, the computer has an X10 Firecracker transmitter plugged in COM1, and I have an X10 TM751 receiver plugged into the nearest convenient outlet.
• I used "bottlerocket" software running under Linux to send X10 control commands out the Firecracker to the TM751, down to the basement to the SR227. The highly complex and arcane Linux command line command to do this is "br A12 on" or "br A12 off" where 'br' is the bottlerocket command, A12 is the code I assigned to the SR227, and, well, you can figure out the rest.
• If you get this far, you are close. You can turn the outlet off and on from the command line. Bravo. Now we need some intelligence. I have a "cron job" running every day. Here is the crontab command line:

  # watering system transformer, runs the watering program every day
  # the program checks the weather and decides whether to run the watering
  28	06	*	*	*	/usr/local/bin/water_more
  

  The Orbit is set to start its watering cycle at 6:30 AM every day.
• Of course, you need the water_more script! Here it is.
• The program uses 'lynx' to check the National Weather Service for my local weather - here - take a look: San Jose Weather. Yesterdays precipitation, and today's forecast temperature. Perfect. The program "reads" the weather report and then decides whether to water.
• Done! The program checks the date, adjusts a bit for season, checks to see if it has rained in the past 24 hours, checks the forecast temperatures, and "decides" whether to water or not. Computers are our servants.

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

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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