How To Use Rainwater In The House And Garden

How To Use Rainwater In The House And Garden

All good things come from above – this also applies to rainwater. It’s far too bad to drain the precious water through downpipes into the ground and let it seep away. We explain how to use rainwater properly in your home and garden.

Those who use rainwater save precious drinking water and money. Statistics show that the average European citizen uses about 150 liters of drinking water per day. But drinking water quality is only absolutely necessary for about half of these uses.

For garden plants, the toilet flushing, the washing machine and also for the car wash for example rain water is suitable even better than expensively prepared drinking water.

Rainwater utilization by means of rain barrel


The simplest way to collect rainwater is to install a rainwater barrel above ground and connect it to the downspout of the roof gutter.

How you can easily build a small rainwater cistern yourself, you will find further down in the text or you can click here.

There are now, in addition to the classic “rain barrel” many other plastic vessels of various shapes. At first glance, they are hardly recognizable as water tanks and can thus additionally be used as a privacy screen or decorative element in the garden.

To ensure that the rainwater enters the tanks cleanly, a water collector with a filter system must be attached to the gutter. If possible, place the collectors in a shady spot and cover the containers so that the water does not become algae or mosquito larvae settle.


Of course, a secure cover with tightly closing lids is also important to protect children and small animals from falling in. Freestanding rain barrels* come in sizes ranging from 150 to 1,000 liters. Some models can also be linked together to form larger units.

Rainwater harvesting in the garden


But how does the collected rainwater get to the plants? The simplest variant is to let the water run from a tap in the lower area of the barrel into watering cans. If you want to have a water tap away from the tank in another place in the garden, for example by the vegetable patch, you can install a swing pump in the appropriate place as a tap for watering water and connect the water tank to the swing pump by means of a garden hose* laid underground.

It is best to hang a submersible pump* in larger collection tanks without an outlet and can then water the plants via a garden hose with a shower head* connected to the pump.

Filter for clean rainwater


A downpipe filter is used to clean the rainwater from leaves and the like.

Filter collectors made of titanium zinc* and copper* filter the rainwater through a sieve that is easy to clean. With a variable attachment piece, you can connect to it either a DN-50 HT pipe, a 3/4-inch garden hose or a rain barrel with a 3/4-inch connection.

Rainwater tank for garden irrigation


A rain barrel is often not big enough or does not fit into the overall appearance of the garden for design reasons. On the basis of the following three picture galleries, we will show you how you can easily build a rainwater tank with connection to the gutter yourself:

Since a filled rainwater tank has a considerable weight, it is important to create a stable, safe and level base before the construction.

Rainwater utilization thanks to underground tank


If you not only want to water your garden, but also use the rainwater for the toilet and washing machine, you can sink larger concrete or plastic tanks into the ground. An investment, which does not amortize in the short term, but with rising drinking water prices becomes increasingly interesting and creates a good environmental conscience.

Sensible use also depends on the annual amount of precipitation on site.


With a complete rainwater harvesting system, you can not only use rainwater for watering the garden, but also connect the toilet flush and the washing machine in the house to it.

This can reduce drinking water consumption by up to 50 percent. The prerequisite is a sufficiently large underground tank to which all rainwater gutters are connected via plastic pipes. High-quality filters in the tank well ensure good water quality.

The underground tank can be installed both in the garden and in a driveway, or under the parking lot or carport. Only the cover of the tank shaft is visible on the surface.


The tank size depends on the size of the family and the garden. Of course, the most cost-effective way is to purchase the tank when the house is built. Subsequent installation is usually more expensive.


Connect all roof surfaces to the underground tank via pipes; the carport, tool shed or garden pavilion also provide their share of rainwater collection. With an underground storage tank, the filter system sits in the tank well directly below the inlet pipes.


For more detailed information on how to go about building your own cistern and what to look for, read here.

Good filtration is crucial for water quality. For new construction, think about a rainwater harvesting system well in advance of backfilling the excavation.

Smaller underground tanks with a capacity of up to 2,000 liters* can usually still be moved into the ground by yourself; larger tanks require machine power.

Earth tanks are available in many different sizes. For a four-person household, it is recommended to install a 3,000- to 4,000-liter tank if you also want to use rainwater for toilets and washing machines.

A rainwater harvesting system is always equipped with a drinking water feeding system, so that in the event of a rainwater shortage, it is possible to switch to a supply of drinking water. The installation of such a system does not require a permit. Depending on the equipment and tank size, it costs between 2,500 and 4,500 euros.

In the long run the rain water use is worthwhile itself in any case. Even after a short time, the purchase will pay for itself – provided, of course, that there is a sufficient amount of precipitation in your region.

In this text we use so-called affiliate links. Products marked with an asterisk (*) are available for purchase. If the purchase comes about, we receive a small commission. However, you do not pay more for the products than usual. You can find out more about affiliates here.

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