Rainwater collectors (récupérateurs d’eau de pluie) have become increasingly popular in recent years, especially among gardeners looking for eco-conscious ways to save water.
It is perfectly legal to collect and use rainwater that falls on your land or property, even if you live in an area subject to water restrictions.
However there are strict rules on what you can use it for, how it is collected and how it can be used in your house.
How to collect it
Rainwater can be collected either using above-ground rainwater collectors or in-ground silos.
You do not need to declare you are collecting it (unless you are pumping it inside your home – see below).
Many old farm buildings in France still have tanks to take the runoff from roofs, which can often be put back in use. Usually the gutter water is fed into a feeder tank, which acts as a filter before going into the storage tank.
For people who do not have ready-installed garden water tanks, devices can be bought at local DIY shops.
Until recently, most had limited storage – 200 litres was common. However, in the last few years 1,000litre and even 2,000litre tanks have arrived.
Expect to pay around €150 for a 1,000litre tank and at least another €50 for kits for the tap and to direct water from the gutters into the tank.
It is possible to link two or more tanks, especially when keeping the vegetable plot productive is a priority.
Building your own tank, either above or below ground, is an alternative. It will cost more in material and time, but can be made large enough to last a drought.
In most places in France it will take years for a rainwater system to pay for itself in lower water bills.
The great advantage, however, is not seeing precious gardens shrivel during droughts.
One point to note is that rainwater can only be collected where it falls.
Article 640 of France’s Civil Code states that landowners should not install systems preventing water running off their property to a neighbouring one.
Dykes cannot be built to prevent rainwater running into another property or to stop it running into yours, nor can you pipe your rainwater to a location which is not part of your property.
The French Code civil also states that if rain has fallen onto a property and remains there it is the legal obligation of that person to deal with it, in the case of stagnating water or health hazards.
Collected rainwater use
Allowed:
- Water plants
- Wash clothes (if water has been disinfected)
- Use in toilets
- Wash floor
- Wash car
Not allowed:
- Drinking
- Use in cooking
- Use in dishwasher
- Use in bath/shower
Inside the house
In contrast to using rainwater in gardens, regulations for its use in the house are strict – it must not be used as drinking water, for cooking, or for use in baths, showers or dishwashers.
This is because it usually contains measurable traces of chemicals and harmful bacteria.
If your roof contains lead or if it is made of asbestos-cement, rainwater gathered from it is banned from use inside houses. It can still be used outside for the garden and washing cars.
Water from tiled, slate or steel roofs can be used for toilets, cleaning floors and washing clothes, although for the latter it should be filtered and treated for bacteria first.
If your property has an individual sewerage system such as a septic tank, the rules are simpler than if you are on a collective system.
In both cases rainwater must only be collected from the roofs of buildings.
Tanks can either be buried or above ground, and it is forbidden to use antifreeze in them.
Any interior taps for rainwater must have a label stating eau non potable and the same must be attached to pipes carrying rainwater to a lavatory.
Rainwater taps are banned from rooms where there are drinking water taps, except for cellars and other annexes such as laundry rooms and garages.
They must be recognisably different from drinking water taps via separate colours and signs, and should have a locking mechanism.
A plumber will need to install a non-return valve for your rainwater pipes, to avoid polluting drinkable water from the water mains.
Rainwater systems inside houses must be maintained every six months, and details of the maintenance logged.
These checks must ensure the system is clean, that eau non potable labels are present, and that there are no connections between the rainwater and the drinking water systems.
Once a year all filters should be washed, the rainwater tank emptied, cleaned and disinfected, and all the valves on the system tested to make sure they work.
Maintenance logs (which can be done by the property owner or a plumber) should include a plan showing the water system in the house, the date it was installed and the dates and details of all maintenance.
It should also include monthly estimates of water use, both for drinking and rainwater in the house.
If you rent out the property, you must explain to tenants how the rainwater system works. Ditto for buyers if you sell the property.
For those on a collective sewage system, installation of a rainwater tank for inside use must be accompanied by a déclaration d'usage des eaux pluviales at the mairie.
You can find out what this entails on the Service Public site.
It must give an address where the tank is installed, and an estimate of the volume of water from all sources used inside the house. It will be used to determine the taxes due for wastewater treatment.
The mairie can send an agent to inspect the system to ensure it does not pose a pollution risk.
If the agent has reason to believe it does, they can require the homeowner to upgrade or disconnect it.
Some departments have grants towards installing rainwater systems – it might be worth asking the mairie they apply where you live.
Note that if a rainwater collection system connected to the sewer is judged to be the cause of contamination, the law includes a fine of €45,000 and up to three years in prison.
