Au fil de l'eau or how to recycle rainwater

Faced with climate changes characterized in some regions by drought in summer and heavy rain in winter, we must adapt our behavior to be more in harmony with our environment. Moreover, as our water bill is constantly increasing, we must react by adopting alternative solutions such as water recycling.

Recovering rainwater: it's a no-brainer

Did you know that up to 50% of the water we use daily in our homes can be replaced by rainwater? So why not do something for the planet and for your wallet? It is certainly a drop in the ocean of bad habits... Water is a resource that is becoming increasingly scarce, so let's take advantage of this gift from heaven with its many virtues.

Rainwater is not drinkable because it contains atmospheric contaminants that are dangerous for humans and animals. It can also be polluted when you collect it from your roof runoff or when you store it in containers. On the other hand, it can provide you with many benefits:

• A savings on your drinking water bill;

• Rainwater is softer than tap water and thus reduces wear and tear on your appliances;

• Lower energy consumption of washing machines;

• Increasing the effectiveness of soaps and laundry detergents;

• Reduced soil erosion around buildings;

• Increased water supply for crops.

A cascade of ideas for the home

Collected and filtered rainwater, depending on the use, can cover a large part of your water needs and reduce your consumption. You can use the recycled water outside for :

• cleaning your terraces and garden furniture for example;

• washing your vehicles

• watering your beautiful plantations and vegetable garden;

• filling your swimming pool or a natural pond;

• having a water reserve in case of fire.

• cleaning your floors and tiles;

• evacuating the waste from your toilet as a flush;

• to wash your clothes;

• to power household appliances.

Recycled water is also very useful in the house for :

Beware, however, of domestic water use. Compared to spring water, rainwater has a better quality, but before it can be used safely, you must treat it to remove any bacteria, particles or organic matter. However, the treatment depends on what you want to use it for. If you want to use it for the toilet or the washing machine, you don't need to do so. But for the shower, take all the necessary precautions to avoid skin diseases. For example, you can use an ultraviolet sterilizer with activated carbon filtration. Installing a water treatment plant will also allow you to have clean water at all times.

Recycle on a larger scale: Using rainwater can be a good idea for municipalities with large water-consuming facilities such as sports fields, equestrian centers, golf courses, etc.

Take the plunge by investing in sustainable management

You'll need to find the right device for your home that makes good use of the rainwater that falls on the roof. Thanks to collectors connected to the downspouts, for example, the water can be channeled to a storage tank. At the entrance of the tank, a small grid performs a first filtration by retaining the debris of the roof (moss and leaves). Upstream of the tank, the water passes through a filter-settler which separates the suspended impurities. These impurities can then be evacuated to the rainwater system via an overflow with a siphon.
Once the water is stored, it must be redistributed. The solution is based on an overpressure pumping unit that conveys the water to the various drawing points. It should be noted that a non-return device (backflow preventer, EN1717 standard required) prevents any accidental mixing with the drinking water network. To wash clothes, a specific filtration (activated carbon or UV treatment) must be added.
The underground tank is more particularly intended for watering and supplying toilets and washing machines. Made of concrete and located near the house, it offers a storage capacity ranging from 2,000 to 10,000 liters. For a 4-person household with an 800^m2 garden, 9,000 liters are required.
In addition to estimating the cubic capacity required, the surface area of the roof and its recovery rate must be taken into account. A tiled roof has a rate of 80-95%, while a green roof is limited to 20%.

Don't be cool with the regulations!

Before installing a water recovery system, you must inform the town hall by submitting a prior declaration of work. For the system to be "crystal clear", many criteria must be respected. Considering the health issues at stake, the installation must be done according to the rules of the art. Without a doubt, this sustainable water management system deserves to be taken into account in a construction project because it raises a few more complications if it is to be grafted onto an existing house. In any case, it is advisable to approach a professional to find the right solution. Moreover, your installation will be subject to regulations and will have to be checked every 6 months concerning the cleanliness of the equipment and the absence of connection between the network intended for consumption and that dedicated to the redistribution of rainwater. Water collected and used inside your home and returned to the sewer system is subject to the sanitation tax. As a homeowner, you are obliged to make a declaration of use at the town hall, as provided for in article R 2224-19-4 of the General Code of Local Authorities. Be careful, if you use rainwater inside your home, the access taps must be clearly identified and you cannot install them in a room where there are taps distributing drinking water (except in cellars, basements and other rooms such as a garage for example).

Stephanie Swiklinski.