21.07.2026
From sky to home: Using rainwater cleanly and safely
Those who want to use rainwater not only for the garden, but also within the home can save a significant amount of drinking water. Modern rainwater utilisation systems make it possible to keep collected rainwater strictly separate from the drinking water system and use it, for example for toilet flushing, washing machines, or cleaning – reliably and in an environmentally friendly way. While collecting rainwater via the roof, gutter, and downpipe forms the first step, the exciting part of the technology begins at the rainwater storage tank. Here, we show you how rainwater harvesting works within the house – step by step, safely and sustainably.
1. Rainwater inlet
2. Preliminary filter
3. Calm inflow
4. Floating intake
5. Overflow siphon incl. animal protection
6. Outlet
7. Sewer
8. Mains water
9. Supply line to extraction points, e.g. toilets
From the preliminary filter to the storage tank
Before the rainwater reaches the rainwater storage tank, it should be freed from coarse impurities by a preliminary filter. Leaves, sand, and other dirt particles are kept out early on, protecting subsequent components such as the pump, filter, or control system and improving the water quality right from the start.
Calm inflow for clearer water
Rainwater is introduced to the rainwater storage tank as gently as possible. A calm inflow ensures that it reaches the bottom without stirring up dirt particles and sediments. The gentle movement simultaneously introduces oxygen into the water, supporting the natural self-cleaning process within the tank.
The integrated overflow syphon ensures that impurities floating on the surface can drain, which should occur at least two to three times a year – for consistently clean water in the storage tank.
Water extraction at the optimal point
The highest quality water in the tank is located approximately 15 cm below the water surface. This is where the floating intake takes place. It draws water from the purest spot, which is then channelled through the rainwater utilisation system to where it is needed – such as for flushing toilets or into the washing machine.
Depending on system configuration – for example, whether a rainwater filter is installed upfront – the floating intake should be equipped with either a fine or coarse filter. This ensures high water quality throughout the system.
Ready for the home – safely separated, automatically controlled
Via floating intake and an appropriate rainwater utilisation system, the water reaches the points of use within the home. If there is ever insufficient rainwater available, the system automatically switches to the mains water supply from the public water network – without interruption.
It is important to adhere to regulations such as EN 1717: rainwater and drinking water must be completely separated. This prevents any backflow into the drinking water network. The water in the integrated drinking water tank is also regularly automatically exchanged, preventing any loss of quality – even during prolonged periods of non-use.
In addition, local regulations and requirements regarding the use of rainwater must be complied with.
Conclusion
A well-thought-out rainwater system ensures that collected water is not only stored but also efficiently used within the home. By using the technology correctly, one can conserve valuable resources in everyday life, reduce environmental impact, and even save money – quietly, efficiently, and reliably operating in the background.
