How to recover rainwater?
No risk that she is crouching?
Is there a double channel?
What type of tank should be installed?
The ideal size of the tank?
How much does it cost ?
To whom should I entrust my work?
What are my obligations?

How to recover rainwater?

It is necessary to install a recuperator , in fact a big tank , in which the water will be stored before being distributed. The rain falls on the roof, is conveyed by the downpipes of gutters, then by collecting ducts to the tank. Be careful, this roof must be inaccessible (no question of using rainwater if you have a roof terrace).

No risk that she is crouching?

To be used inside our homes, rainwater will be filtered at different levels. At first, gutters to the inside of the tank. Then, in a second step, the tank at home, with two filter elements : one that retains fine sludge and sediment (mandatory), and the other, activated carbon, which traps odors (not mandatory) . To supply rainwater to a washing machine, it is also necessary to install a UVC anti-bactericidal lamp .

Is there a double channel?

The water of the pre-purified tank is pumped on the surface (the deposits thus remain at the bottom of the tank), again filtered and rebalanced in pH ; then an electric pump of automatic feeding will supply the various points of drawing. Attention, to be able to use the rainwater in the house, it is obligatory to install a double network of pipes clearly identified by a pictogram "water not potable", then to install specific taps (square head or cache entry) that a child must not not be able to handle. Finally, it is essential to provide an "overflow disconnector" (standard NF EN 17 17) in order to be able to switch to the city network when the tank is empty without mixing drinking water and rainwater.

What type of tank should be installed?

▪ For watering the garden : a plastic tub (opaque) or wood to be installed behind the house and above ground. ▪ To feed the house , two options: a flexible tank (opaque) installed in the basement or crawl space on perfectly level ground. It can not be placed in a transit area (such as a driveway), but it is less expensive and lighter than a rigid tank. Or a tank of high density polyethylene or concrete, buried in the garden, which offers greater storage capacity and keeps the water away from light and heat. More expensive and heavy (it requires a crane), it remineralizes water and neutralize its naturally acidic pH.

The ideal size of the tank?

Everything depends on his needs. On average, 600 liters of rainwater can be recovered per year per square meter of roof . For a family of 4 people, we plan on a tank of 4 000 l for the regions located in the north and 6 000 l for the departments located in the south (75 m3 / year, in Brest, against 80 m3 of water / year, in Nice!).

How much does it cost ?

▪ Count 3 000 € HT for a buried container of 3500 l reserved for outdoor use and more than 5 500 € HT if it is a tank of 7,500 l for domestic use , all equipped, to which it is necessary add between € 1,000 and € 1,500 for installation and, depending on the company, an additional € 1,000 for the connection inside the house. ▪ Until December 31, 2011, a tax credit is granted to individuals who equip their main residence : up to € 8,000 for a single person and € 16,000 for a couple. Namely: some departments, regions and communes have put in place means-tested grants.

To whom should I entrust my work?

To a certified company which, in addition to an invoice, will provide you with a commissioning form (defined in the appendix to the decree of 21 August 2008) attesting to the conformity of the installation. Some companies offer free quotes (type "rainwater collector" on Google and compare).

What are my obligations?

▪ Cleanliness , signage and disconnection of the rainwater network with the drinking water network should be checked twice a year.

▪ Filters and storage tanks must be cleaned every year.

▪ A sanitary record of maintenance of the storage tank and filters mentioning the name of the person in charge of the maintenance, the plan of the recovery device, the dates of the verifications carried out ... will have to be kept up to date.

▪ It is necessary to declare to your town hall the installation of a recuperator , because the worn rainwater, unless equipped with a septic tank, will be poured into the public sewer network. This reprocessing may be subject to a flat-rate tax (maximum 60 € per year), calculated from a rainwater consumption survey.

Thanks to Valéry Jimonet , President of Snarep (National Union of Rainwater Harvesting Actors).