While attending EC1205 in Offenburg two weeks ago, I was demoing some of the Flukso site's features on Friday night. When looking at the hourly water chart, I noticed anomalous water usage at my home. The Fluksometer was reading a nearly constant water consumption of 11 liters per minute for over an hour already. Since our electricity consumption was near its base load, I figured my better half and the children were not at home. I then SMS'ed my wife asking her to check what was going on. Somewhat grudgingly she went home and noticed that one of the toilets hadn't properly terminated its flushing operation. In electricity terms, there was a short circuit between the water supply and the drain.
A quick calculation shows that this flushing incident caused a total of 1486 liters of water to flow down the literal and metaphorical toilet in a 2h15m time span. Money-wise this amounts to less than 4EUR. Nevertheless, this kind of needless waste bothers me.
Instead of haphazardly discovering these kind of leaks, we should have a monitoring system in place that performs a number of checks automatically. As a big bonus, it will not be me spoiling the party anymore, but rather an innocent bot!
Ironically, server-side threshold alerts have been running in alpha mode for quite a while now. The only thing that's still lacking is the configuration interface. I've bumped the priority of the feature to high. That should mean a beta in a couple of weeks time.
Comments
An acquantaince had a very senstive water tank level measurement system using capacitance wires. It was apparently so senstive that by looking at the graphs you could tell that someone had flushed the toilet during the night. My water tank uses a differential pressure sensor, which has enough noise on the readings that I filter them with a simple rolling average filter and hysteresis, before inferring how much water is collected or used. Together with a water efficient toilet, the filtering prevents night time analysis of my water usage.
These water readings are obtained by piggybacking on the utility's water meter, see this blog post. I assume that you use a rainwater tank to flush your toilets.
Do you have a more detailed description on the capacitance wires and differential pressure sensor methods mentioned in your comment?
My differential pressure sensor is from http://www.electrosense.com.au/
It isn't one listed on the web page. It's similar to the Aquagage, but just has an RS232 output.
The differential pressure sensor sits at the bottom of the water tank, with a tube to the surface (with the wires inside). The sensor thus measures the difference between pressure at the bottom of the tank, and that at the surface. One atmosphere is about 10m of water. My sensor is a 2m unit.
The capacitance sensor is no longer functioning due to corrosion. The technique is to hang two wires in the water. One is insulated, the other is not. The water becomes part of the uninsulated conductor, and the capacitance is determined by the length of water around the insulated wire, the diameter of the wire, and the thickness of the insulation.
+1 for monitoring/alerting features :-)