Clean water has a positive impact on human health, the environment and the economy. The EPA works to minimise pollution and improve water quality, including collaborating with other agencies on Our Living River.

Water pollution can threaten both human health and the health of our waterways. Our water resources are of major environmental, social and economic value to NSW and when water is polluted the value of the resource can be reduced.

Water pollution can be caused by both point source (such as industrial and treated sewage discharges) and diffuse sources (such as stormwater runoff from agriculture and urban areas).

The Protection of the Environment Operations Act 1997 (POEO Act) provides the statutory framework for managing water pollution in NSW. It is supported by the Protection of the Environment Operations (General) Regulation 2009, which among other functions prescribes certain matters for the purposes of the definition of water pollution.

There is a broad allocation of responsibilities under the POEO Act between the EPA, local councils and other public authorities. The EPA is the appropriate regulatory authority for:

  • activities listed in Schedule 1 of the POEO Act and the premises where they are carried out
  • activities carried out by a State or public authority
  • other activities in relation to which a licence regulating water pollution is issued.

In nearly all other cases, the regulatory authority is the relevant local council.

Chapters 16-20 of the NSW State of the Environment 2015 report provide a comprehensive summary of water quality status and trends in NSW waterways.

What is water pollution?

The definition of 'water pollution' in the Protection of the Environment Operations Act 1997 (POEO Act) sets out general and specific circumstances that constitute pollution. At its broadest, water pollution means introducing any matter into waters which changes the physical, chemical or biological condition of the water. It also includes placing any matter where it might fall, descend, be washed, be blown or percolates into any waters (e.g. soil which might washed into a waterway).

Additionally, the Protection of the Environment Operations (General) Regulation 2009 (see Schedule 5) includes a list of specific substances (prescribed matter) which, if they are introduced onto or into waters, are automatically assumed to constitute pollution of waters (e.g. animal matter, soil, thermal waste, any matter that contains faecal coliforms, pesticides, etc.).

It is an offence under section 120 of the POEO Act to pollute waters. However, section 121 and 122 of the POEO Act provides a defence against prosecution under section 120 where the pollution was regulated by an environment protection licence or regulation which was complied with fully.


Water pollution is often discussed in terms of its source:

Point source water pollution comes from a discrete source, such as a pipe or drain flowing from an industrial activity. Point source pollution can be critical to the health of a waterway as it occurs independently of flow conditions and can therefore impact a waterway when it has the least ability to accommodate the pollution, especially in dry conditions.

Diffuse source water pollution arises from a multitude of diverse urban and rural land uses across a catchment, rather than a discrete point source. Diffuse source water pollution is mainly driven by rainfall runoff, particularly from storms, although contamination of underground water systems and aquifers can occur over long periods independently of rainfall and may be linked to current or past land uses on the ground.

For further information on diffuse source water pollution see Diffuse source water pollution.

More information

See the Office of Environment and Heritage website for