Onsite Sewage Management System Application for Plumbing and Drainage Inspection. All plumbing and drainage works must be in accordance with the Plumbing and Drainage Act 2011. This includes provision of a Notice of Work, Certificate of Compliance and a Sewer Service Diagram by the licensed plumber within the required time periods. Plumbing works are required to be inspected by Council. Principle Certifiers are not authorised to inspect plumbing works.