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Sunday, August 16th, 2015 08:02 pm
One of the new capabilities I wanted to add to v1.5 system is the ability to monitor water usage. I started by adding support for hardware water meters (of a typical pulse type), and even bought nice water meter device like this one:

It works, but while working on this feature I realized that supporting water meter is not enough. Ideally I would like to know how much water is used by every zone, so I can optimize watering for maximum results while conserving water.

But it is impractical to equip every zone with a separate water meter. It is also hard to use common water meter to measure individual zones - in some cases it may require multiple water meters (e.g. my setup uses three separate water feed connections), also sometimes water is dispensed manually, for hand-watering from the same water line (going through the same water meter).

However there is a way to do it, and actually it does not even require connected water meter :-)
The water flow for each zone is relatively constant when it is running, and if you calibrate each watering zone you can reasonably reliably calculate the amount of water used simply based on the run time of the zone.

To calibrate each zone you can either use common connected water meter (if there is one installed in the system), or you can use simple cheap stand-alone water meter like this one:

It costs only 10-15 dollars, and it allows measuring water consumption. You can just run each zone for 5-10 minutes, measure the amount of water used, and calculate calibration value. Or as a poor-man option you can use your main house water meter - it has dials you can read, just need to make sure nobody in the house is using water while you are measuring it.
Once it is done, the system can be running with no water meter at all, while producing reasonably accurate water usage reports.

Of course, ideally would be to have real connected water meter as well - it can be used to cross-check calculated and actual consumption, also it could be really helpful as a mechanism for detecting broken valves and water leaks. But minimal setup can run without it.

This mechanism for water metering (both computed water usage and actual water meter support) are part of the v1.5 firmware. I'm planning to have it ready for v1.5 system installation this fall - probably end of September or so.