Drought orders drive interest in rainwater systems

The increasing number of "drought" orders, which limit the use of tap water, along with the expected rise in water prices, is encouraging people to look into rainwater harvesting systems. These systems can provide water for tasks like washing cars, flushing toilets, and even operating washing machines, depending on local regulations.

Rainwater systems vary in design and cost

Above-ground rainwater systems are affordable and simple to install, while underground tanks offer greater storage capacity and can be connected to household plumbing. The size of the tank must be tailored to local rainfall, roof area, and household needs, with capacities ranging from a few hundred to several thousand liters. Costs can range from under 50 euros for a small system to over 10,000 euros for a full installation.

France's 2026 summer highlights water stress

In France, the summer of 2026 was the hottest on record, with an average temperature of 24°C and a 40% drop in rainfall. This led to strict water usage restrictions, emphasizing the strain on water resources. Rainwater harvesting can ease this pressure, as most tap water in France comes from groundwater and surface water, both of which are under stress during dry periods.

How rainwater systems work

Rainwater is collected through gutters and directed to a tank via a collector connected to the downspout. The system must include an overflow to prevent tank overflow, which could lead to flooding or soil erosion. Above-ground systems are easy to install, while underground systems are more durable and can be linked to household plumbing for non-potable uses.

Rainwater usage and regulations

Since 2008, rainwater can be used for non-potable indoor tasks, potentially covering 44% of a household’s water needs. However, the actual savings depend on the system’s size and efficiency. Some local governments offer financial assistance for purchasing rainwater systems, and installation requires a declaration to local authorities.

Costs and benefits of rainwater systems

A 300-liter garden rainwater system can save between 3 to 6 cubic meters of potable water annually, reducing water bills by about 15 to 30 euros. However, the return on investment can take several years or even decades. The average cost of tap water in France is 4.89 euros per cubic meter, though it is gradually rising.

Installation and maintenance considerations

Using rainwater from harvesters is allowed in some situations but not automatically permitted, so it is important to check local regulations. Essential components include gutters, filters, and tank covers. Regular maintenance is needed, such as cleaning gutters and emptying tanks in winter. Additional precautions, like mesh grilles, can prevent mosquito breeding, and proper installation can reduce risks like soil cracks.