Water usage 2019 Q4

Our first quarterly water bill in the new house means water usage data!

While water usage is not a "passive house" criterion, it is certainly related to the general principles of trying to live sustainably.

From 14 October 2019 through 15 January 2020 we used 16,000L of water supplied from Sydney water (173L/day). While I don't have super precise numbers from the rainwater tank we probably used about the same about from the rainwater tank over the same period. Possibly the amount of rainwater used was a little bit more than that, but it could not have been much more.

The reasoning behind estimating 16000 - 20000L from the rainwater tank... We had ~176mm of rain in mid-September which filled the tank (and then some), we had an additional ~22mm of rain the week before the water bill period started, so it would have been full at the start of the billing period (17500L capacity). On November 3rd we received 14mm of rain which would have topped it up a bit. In December we received less than 1mm of rain. Our first significant rainfall of 2020 was on January 17th.

We use rainwater to flush toilets, wash clothes and for all exterior water taps. We ran out of rainwater sometime between the 20th of December and the 7th of January (the water level was too low to draw from as evidenced by clear city water in the toilets on our return from holiday [yes, the house only had 3 people rather than 4 while we were gone]).

The water bill water indicated that we used 173L/day of city water (~ 44L/day per person), and based on the information above we used approximately the same amount of water per day from the rainwater tank (< 51L/day per person). I am 100% confident that we used less than half that used by the average Sydney resident (~ 210L/day).

In comparison at ~ 346L/day total usage is half of the ~740L/day we had in the old house... props to no leaks and water conserving plumbing fittings.

Due to the rain over the past few days the rain water tank is back to about 1/3 capacity.

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