Rainwater recovery: buried or above-ground vat?

Deciding to collect stormwater to water your garden, clean your car or clean your toilet and wash your laundry is a responsible but also economical choice. There are many ways to install a rainwater collector, depending on how the water is harvested and the space you have for this installation will be used.

In particular, you will have a first choice between an above-ground tank and a buried tank. Both types of tanks have their advantages and are not intended for the same uses.

Why choose an above-ground tank to collect rainwater?

An above-ground rainwater recovery tank is directly connected to your gutter and simply placed on the floor of your property. Offering a capacity of up to 1700 litres, these tanks are ideal for collecting small amounts of rainwater. The above-ground tank is mainly suitable for outdoor use of collected rainwater, especially for watering the garden or cleaning your car. It is often chosen by individuals for its simplicity of installation that does not require the intervention of a professional.

The above-ground tank, on the other hand, has the disadvantage of being sensitive to frost. If you choose an outdoor waste picker, you will have to return it, or at least protect it well during the winter.

The polyethylene vats are perfect for outdoor installations. Economical, easy to install and move, they connect to your gutter with ease with special kits. When the tank is full, simply remove the fitting so it doesn't overflow.

As for the distribution of water, it is provided by a simple faucet already integrated into the tank or to be connected to the waste picker.

The benefits of the buried rainwater recovery tank

If you want to use rainwater inside your home, for example for your toilets, to clean the floors but also to wash your laundry (a specific treatment of water is necessary),a rainwater recovery tank to burywill be more suitable. This system is still relatively unknown to the general public but it allows to value rainwater in greater quantities and for more uses.

This type of tank will allow you to recover larger amounts of water and can be used throughout the year, summer and winter. Because the container is underground, there is no longer a risk of exposure to frost or sun. The water is constantly protected from the cold and UV rays. The burying tanks proposed by multitanks can hold up to 10,000 L of water.

Unlike rainwater recovered from an above-ground tank, the water remains perfectly transparent and odourless. A buried facility is not only about storing water, it filters it - water passes through an active charcoal filter and a sediment filter - before redistributing it via a water infal separate from that of drinking water.

The installation of the buried tank

While there are many advantages to it, installation of a buried tankrainwater recovery, however, is more complex than that of an above-ground tank, since it requires a hole to be dug. It is also more expensive than installing an aerial tank that simply requires the purchase of a tank and a connection to connect it to the gutter. But the investment is quickly profitable thanks to the savings made by using rainwater to clean his laundry, his floors or for the evacuation of his toilets, in addition to using it to water his garden.

If you intend to collect stormwater for use inside your home, you will need to study your needs in order to invest in a tank of the right size. Of course, the amount of water recovered from this technique differs from region to region. A Norman family will apparently recover more water during the year than a household living in the south-east of France. It may then be necessary to hire a professional to install a buried tank.

Buried tank and regulation

The operation of a burying tank is also a little more complex and above all more controlled than that of an above-ground (or aerial) tank. In addition to the hole to be drilled, a specific connection is required and special equipment must be installed in a mandatory manner. Among them:

- A pump that will extract the water and direct it to the water distribution system.
- A filtration system
- A ventilation system
- An anti-return system that prevents communication between rainwater and drinking water
- A level indicator to determine how much water the tank contains
- A overflow system to drain water when the tank is filled

Please note that rainwater and drinking water infed must be separated. They must not communicate under any circumstances and a report that rainwater is not safe to drink must be clearly visible.