Drainage locally lowers the groundwater level. When this is not desirable, for example in the case of groundwater underloading near wooden pile foundations, foundation on steel and infrastructure, drainage can be reduced by modifying the drainage system. This can be done in several ways:
- Remove the drainage system in its entirety;
- Raise the drainage base so that the groundwater level is not brought below a certain point;
- Adopt a flexible drainage base that depends on the groundwater level.
Again, this measure must strike a good balance between avoiding flooding and preventing groundwater levels that are too low.
The municipality has the groundwater care task, a best-effort obligation, for the groundwater in the public area and the property owners for the private area. Relevant laws and regulations are the Environmental Management Act and the Water Act.