Teacher background information
What is wastewater?
Wastewater is a hidden part of everyday life and is collected from households, commercial businesses and industries. It is directed by sewers to treatment plants and treated to an environmentally acceptable standard.
The treated wastewater is then either:
- returned to the marine environment via ocean outfalls
- reused in horticulture or to irrigate recreational areas
- allowed to infiltrate back into the ground or evaporate.
In WA, Water Corporation is responsible for the treatment and disposal of wastewater. It operates more than 100 wastewater treatment facilities around the State.
Drainage systems consist of pipes or open-channel drains that convey storm water runoff and groundwater to natural water bodies such as rivers, wetlands, and the ocean or to compensating basins. They often follow the route of natural watercourses that existed before any land development or clearing took place.
Drainage systems prevent flooding of developed land from surface runoff and from rising groundwater levels. In areas or high water tables, drainage systems lower the groundwater level so that land can be developed.
Storm water is not treated and in some cases leads directly to our water bodies such as rivers, lakes, wetlands or the ocean. Alternatively, the water seeps back into the ground and is taken up by plants, evaporates or gradually trickles down into the groundwater. Storm water runoff easily collects pollutants along its path.
Impact of littering
Litter is a serious pollution issue that affects our waterways, coastline and ocean impacting on wildlife, human health and the marine environment. In 2015 it was estimated that 8 billion tonnes of litter and waste debris enters the world’s oceans annually and most of this comes from the land. Plastics create up to 99% of this debris. Rivers, streams and storm water drains transport litter hundreds of kilometres to the ocean where currents and wind carry them all over the world.
Nutrients can be pollutants
Nutrients are elements or compounds including nitrogen, phosphorus and organic carbon. They enter the rivers from the catchments through drains, surface runoff and groundwater. The most common sources of nutrients entering our rivers include fertilisers, plant matter (e.g. grass clippings, leaves), detergents, sewage and animal waste.
Nutrients are essential for plant growth, including algae. However excess nutrients fuel algal blooms and can promote harmful algae, which take oxygen out of water. Low oxygen conditions and toxic algal blooms can result in fish deaths.
Where does storm water go at school?
How pollution affects our catchment