State Environmental Planning Policy (Exempt and Complying Development Codes) 2008
(1) All stormwater drainage collecting as a result of the erection of, or alterations or additions to, a dwelling house or ancillary development must be conveyed by a gravity fed or charged system to:
(a) a public drainage system, or
(b) an inter-allotment drainage system, or
(c) an on-site disposal system.
(2) All stormwater drainage systems within a lot and the connection to a public or an inter-allotment drainage system must:
(a) if an approval is required under section 68 of the Local Government Act 1993, be approved under that Act, or
(b) if an approval is not required under section 68 of the Local Government Act 1993, comply with any requirements for the disposal of stormwater drainage contained in a development control plan that is applicable to the land.