What are the rules for using rainwater for domestic use?

Recovering and using rainwater for domestic use can represent significant savings on your water consumption bill. But beware, rainwater is non-drinkable water, because potentially contaminated, which cannot be used just anyhow, and especially not be consumed. Very specific rules, defined by legislation, apply to the recovery and storage of rainwater. Explanations.

Rainwater: characteristics that require regulations for its use

“Rainwater” refers to water that can be collected at home. after runoff on the roof and storage in tank “, as indicated by the Ministry of Health.

This is non-potable water because it potentially presents a risk of being contaminated by bacteria, due to its passage on the roof of a dwelling, and by pesticides or metals, such as asbestos. , which may also be present on the roof of the house. Rainwater is therefore untreated water.

Unlike water intended for human consumption, which complies with the quality rules defined by the Public Health Code, rainwater must therefore not be used for any purpose in order to guarantee the health safety of consumers.

Thus, in general, the use of rainwater is strictly prohibited inside health establishments and establishments, social and medical-social, accommodation for the elderly, medical offices, dental offices. , medical biology analysis laboratories, blood transfusion establishments, as well as crèches, and nursery and elementary schools.

On the other hand, any connection, temporary or permanent, of the rainwater network with the drinking water network is prohibited.

How can rainwater be used for domestic use? What are the applicable rules?

Given its possible chemical, bacteriological or parasitic contamination, rainwater must in no case be used for food consumption. This includes drinking it, using it for cooking or washing dishes. This is why it is strictly forbidden to recover rainwater for such domestic uses.

The recovery and use of rainwater inside and outside buildings, whether or not they are connected to a public drinking water distribution network, are regulated by an order published in the Journal official on August 28, 2008. The latter strictly defines the conditions under which rainwater can be used, in particular at home.

This decree thus stipulates that it is possible to use rainwater inside your house only to fill the toilet flush, wash the floors, and wash your clothes, provided you use a adapted water treatment device that ensures the disinfection of rainwater. However, it is prohibited to use rainwater for these practices if it is recovered after having run off on a roof containing asbestos cement or lead.

On the other hand, it is authorized to use rainwater outside his house, but on the express condition of installing a rainwater recovery system in his home, to clean his car. , or watering your garden. In the latter case, this mandatory equipment allows the consumption of products grown in a garden and which have been watered with rainwater.

The recovery and use of rainwater for domestic use requires the installation of specific equipment

If rainwater, which is not drinking water, cannot be used for food consumption, some of its uses are authorized, in particular inside the house, on condition that it has been installed beforehand specific equipment intended for its recovery and storage.

The obligation to install a rainwater storage tank

Thus, the storage of rainwater which has previously run off the roof of a dwelling must be carried out by means of an above-ground or buried tank equipped with filters which make it possible to purify this rainwater to a minimum. Caution: no antifreeze product should be poured into this rainwater storage equipment.

It is possible to connect a rainwater storage tank to a collective sanitation network, i.e. the “all-to-the-sewer” whose role is to evacuate and treat the domestic wastewater (those from toilets, sinks, kitchens, washing machines, etc.). In this case, and if the rainwater is used inside the house, by virtue of article R 2224-19-4 of the General Code of Local Authorities, it is mandatory to make a declaration to the sanitation service of the town hall of his commune. This declaration must mention the identification of the dwelling concerned and an assessment of the volumes of rainwater used inside the residence.

On the other hand, if the rainwater is used for certain authorized uses inside a house, any taps connected to the storage tank for this water must be clearly identified by means of signage. specific (a mention “non-potable water” and an explicit pictogram). These taps must also be equipped with a mechanism (not attached to the taps) allowing them to be locked. In addition, except in an adjoining room such as a cellar, basement, garage, etc., it is prohibited to install taps that supply rainwater in a room where there are taps that supply the house with drinking water.

Regarding the signage specifying non-potable water, the same precaution must be taken in the toilets if rainwater is also used there.

Mandatory maintenance of rainwater harvesting and storage equipment

If rainwater is used inside the house, owners are required to regularly maintain and monitor their rainwater harvesting and storage equipment.

Thus, it is necessary to check the cleanliness of all this equipment every 6 months, as well as the presence of the “non-potable water” sign. Every 6 months, it is also mandatory to ensure that there is no connection between the water network intended for human consumption and that for the distribution of rainwater.

Then, at least once a year, the filters of the rainwater storage tank must be cleaned, just like its taps if it is equipped with them, and this tank must be emptied, cleaning and disinfection. It is possible to carry out these procedures yourself or to call on a specialized company.

To justify the performance of this general maintenance, it is mandatory to keep an up-to-date sanitary maintenance log for these rainwater recovery and storage facilities. This document must mention the detailed plan of the rainwater recovery equipment, their commissioning sheet, the dates of the checks and maintenance operations, the monthly statement of the indexes of the water volume evaluation systems used inside the dwelling if they are connected to the waste water collection network and, where applicable, the name and address of the company responsible for maintenance.

Verification of the proper maintenance of rainwater harvesting and storage equipment and its monitoring by their owner can be carried out by the local authorities. As the Department of Health points out, In order to prevent the risks of contamination of the public drinking water network, article 57 of the law on water and aquatic environments introduced the possibility for water service agents, when using a water resource different from that coming from the public distribution network, to access private properties to carry out inspections of indoor drinking water distribution installations and abstraction works, wells and boreholes ».

Any contamination of the public drinking water distribution network, due in particular to a lack of maintenance, may in fact lead to administrative and penal sanctions provided for by the Public Health Code.

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