Do you need Building Control approval to install a septic tank/sewage treatment system?
Generally, septic tank installs do not require Building Control approval if you are replacing like-for-like or installing a tank in the same place as the original. If you are moving the location of the septic tank, you may need approval.
Sewage treatment plant installs generally do require approval from Building Control. Always check with your local council, as different council areas vary.