So many people are unaware for example that you cannot for example put anything into surface water drains other than surface water. I lost track of the number of companies who were washing staff cars on site, with the dirty water produced going into surface water drains back when I used to do resource efficiency visits for Envirowise. There were plenty of others putting "clean" condensate from compressors etc. into surface or groundwater.
Doing it yourself or getting a non-professional to do it for you might well be a false economy.