Some of you know my indiscriminate interest in understanding the unfathomable, i.e. utilities costs. My new target is the enormous water consumption of my summer house, especially painful in a country (France) where water for non residents costs a feckin’ €4 per cubic meter (hear that, Irish friends?)
This may sound like “not much” (0.4 euro cents per liter) until you receive the bill stating that your house consumes 2,500 cubic meters per year (almost 7 cubic meters PER DAY on average), with no more than 80 days per year occupancy.
The first thing I thought is a leak, and a big one. However, the water circuit is all exposed in the great french invention of the “vide sanitaire” or crawlspace: since the house is built on the side of a rather steep hill, the crawlspace in many places is higher than a normal ceiling, allowing easy access for inspections.
Surely a leak of those proportions should leave visible traces (puddles of water, humidity) which to be honest we could not find. As always in these cases, the problem starts with the fact I DO NOT KNOW how much water a house like mine should normally consume. Without a benchmark, it is hard to assess exactly how bad the problem is.
So I got a plumber to divide the circuit in three sub-circuits: one feeding the yard, one for the pool with the surrounding lawn and one for the house, each with its own sluice valve and counter.
After a mere few days of observation, I now know the following:
- In a normal day when there’s people, our house will consume about 400 liters of water; of course this will vary with the number of people.
- The sprinklers watering the lawn around the pool are quite thirsty, consuming about 1 cubic meter per day.
- The rocky garden drip watering system in comparison is more thrifty, requiring only 1.8 cubic meters per day for a much larger expanse.
- The pool itself requires topping up every 10-12 days, to compensate for evaporation and – perhaps – a few small leaks, at the rate of about 2.2 cubic meters each time.
Tweaking the programming of the various sprinklers I have now settled on a yearly theoretical consumption of around 350 cubic meters (the vast majority of which is used during the summer) a far cry from the 2,500 of my last bill !
Moreover, the new system will make easy to shut off altogether the branches I am not using (the house when we’re not there, the garden except during the summer, the pool except when it is being refilled) making mistakes less likely and easier to correct, also thanks to a friendly neighbour which is kind enough to keep an eye on my house in our absence.
The proof of course will be in the pudding, i.e. my next bill, but also in the negotiation I will have on monday with the water company, as there is a little law in France that allows to get a kickback in case there’s a leak certified by the bill of the plumber.