Collecting rainwater
Reducing our consumption of drinking water – the production and transport of which are costly in terms of energy – is essential. A good solution is to increase our domestic use of rainwater.
1. Specify your project
Unfit for drinking, cooking or personal hygiene, rainwater can be used for many other purposes: watering green spaces, cleaning floors or cars, filling toilets, etc.
But washing your laundry in the machine using rainwater is more complex and expensive than irrigating your vegetable garden. So start by assessing how far you want to go in your approach, and specify your motivations: reduce your water bill? Gain autonomy in the event of a drought order? Participate in the collective effort to improve rainwater management complicated by climate change?
2. Choose your tank
Your project will also depend on the surface area of the roof that collects the water. You can use an online calculation tool (read the box at the end of the article) in order to assess the ideal dimensions of the tank. For the garden and washing floors, an outdoor model of 0.3 to 1 m3 is sufficient. Be careful to choose an opaque one, treated against UV rays and equipped with an anti-mosquito filter. For larger uses, such as supplying the flush, you should plan for an underground tank of 5 to 10 m3. And call a professional for the necessary separate connections.
3. Find out about the regulations
The rainwater connection inside the house must be separated from the drinking water supply network in order to avoid any mixing between the two. Each tap delivering non-potable water must therefore be identified as such. Since September 1, new regulations govern the domestic uses of rainwater. They are authorized without administrative procedure, except for washing clothes, which must be declared to the prefecture.
4. Maintain your equipment
After falling from the sky, rainwater flows down a roof, encounters large or small debris, then stagnates in a tank. Hence the importance of maintaining the filters properly. It is mandatory to empty and clean any tank, whether outdoor or underground, at least once a year. To make your garden recovery equipment last, do not hesitate to empty it before winter to avoid frost attacks.
Sources: Jérémie Steininger, general delegate of the actors of the treatment of the plot’s water (Atep), Water information center.
