By disconnecting the downspout from the sewer system in buildings, the sewer system and the treatment plant are relieved of their load, overflows of dirty water into the surface water are prevented and the groundwater is replenished. When the downspout is disconnected, provisions must be made that are appropriate to the soil and the available space, so that the building and the environment do not suffer damage and inconvenience. When disconnecting the downspout, it is important to ensure that the rainwater is directed away from the house to avoid moisture problems.
One of the determining factors is the degree of infiltration capacity of the soil. In sandy soils, for example, water can infiltrate easily. There are various possibilities for this: pond, ditch, infiltration crates or a connection to a ditch.
The rainwater can be drained via an open gutter to a pond, ditch or, if there is one, to a ditch.
If space is limited, the downspout can be linked to underground facilities such as infiltration crates, IT sewers or pocket wells.
Another possibility is that the rainwater is stored and used for example for toilet flushing and for watering the garden. This measure can be found under Rainwater usage.
All these measures help to prevent flooding of the streets and gardens during heavy showers. Draining rainwater via a well-designed gutter beautifies the garden; if it is drained via a ditch, it can slowly infiltrate the soil and thus naturally replenish the groundwater.
How to design a garden in a water friendly way and what to look out for can be found at Stichting Rioned.