You require this approval to connect (directly or indirectly) to a public sewerage network. This approval only authorises you to make the connection to the public system and a separate approval is generally required to conduct work on the sewerage network itself.
Public sewerage networks may be regulated by different authorities in different areas of NSW.
Please note that plumbing and drainage work can only be carried out by individuals that hold the relevant professional licences.
Please consult the relevant authority for more information.