Rainwater is an important part of the water cycle. It feeds waterways and thus helps to preserve them. Sustainable rainwater management in urban areas benefits both people and the environment.

Watering the garden

Watering with rainwater: Watering plants, trees, fruits, and vegetables around the house and garden is the simplest and most sensible use of rainwater.

To use rainwater in the garden, water running off the roof can be directed into a rainwater collection tank. This soft water is ideal for garden plants. Many plants tolerate rainwater better than hard tap water, such as rhododendrons and geraniums.

You can also fill garden ponds with rainwater. Using rainwater for watering is safe from a health perspective.

Watering Effectively

A key factor in efficient watering is the time of day. The best time is early in the morning, at sunrise. In the summer, this means watering between 4 a.m. and 6 a.m., when evaporation is minimal and the water can slowly seep into the soil.

When watering the garden by hand, with a hose, or using a watering can, it’s often done in the evening because there isn’t enough time in the morning. However, it’s best not to let the plants spend the night with wet leaves.

A smart irrigation system delivers the right amount of water at the right time, helping to conserve precious drinking water. However, manufacturing the technical equipment needed for a smart garden consumes a lot of energy and resources and generates electronic waste after a few years.

From an environmental perspective, the effectiveness of smart irrigation has not yet been clearly established. Water savings must be weighed against the increased
resources required for technical devices and distribution equipment. Smart technology is expected to become widespread in private gardens in the coming years, just as robotic lawn mowers have already done.

It is therefore advisable, even in a smart garden, to optimize water use by choosing the right plants and using rainwater.

Using Rainwater in the Home

Rainwater for flushing toilets

There is no risk of infection. A dual plumbing system is generally not necessary, because during prolonged dry spells, the rainwater tank can be topped off with drinking water. However, using rainwater for flushing toilets may result in wastewater treatment fees.

Rainwater for laundry

Using rainwater to do laundry has environmental benefits. Washing with soft water reduces detergent use by about 20%.

However, this benefit must be weighed against hygiene concerns, especially for people at risk: although washing at the right temperature with detergent generally kills harmful germs, subsequent rinses with cold water do not guarantee their removal, which can lead to contamination of the laundry.

This risk can be eliminated only by treating the water properly or by ironing the laundry after washing.

It is therefore important to take these precautions if you plan to use rainwater for laundry, especially for people with compromised immune systems: young children, the elderly, the sick, and particularly those with weakened natural defenses. No health risks should be taken when it comes to these groups.