For my part, contact with authorities both as a private person and at work has varied from authority to authority and even from administrator to administrator. You can be unlucky and come across administrators who are both incompetent and "paragraph riders" at the same time.
In the Summer Cottage area where we have a small cottage, a few years ago we had to install a common infiltration facility for the BDT water. Two years later, after the installation was done (all cottage owners had to pay out of own wallet ). New administrators in the municipality and they said: No, you do not have to do that in your area. The bedrock itself takes care of it. We've done measurements and ... and so on. So it can go.
BDT water means wastewater from baths, dishes and laundry. This is also called greywater and has normally seen a large volume, but little load if you exclude phosphate from soap and detergent. BDT water can be purified separately with simpler methods, for example by sludge separation and sewage infiltration. For the most part, however, BDT water is mixed with heavily loaded wastewater from toilets (toilet water), which gives so-called mixed wastewater, also called black water.
sv.wikipedia.org
And yes we performed tests on the BDT water that we submitted to the administrators who forced us to install the BDT infiltration facility. It did not help.It was like a Kafka novel, short story.