Domestic and urban stormwater drains are usually at ground level for effective rainwater drainage. They’re placed to collect water from outside buildings – rooves, downspouts and yards – and from roads and paved areas.
Sewer traps receive water from inside buildings – bathrooms, laundries and kitchens – and should be raised above ground level to prevent surface water getting in. This is where all wastewater and liquid chemical residues such as household cleaning products should go!
Only rain down the drain
So you’re just washing the car or cleaning the brushes after that painting job. But if the soapy water, paint residue or turps goes down the stormwater drain, you’re not getting rid of it – only moving it to another place.
It travels through a system of underground pipes, designed to prevent flooding by collecting rainwater, and is released untreated into streams, rivers or the sea. So any waste entering our stormwater drains can affect water quality and the habitat of aquatic plants and animals. People’s health may also Help us protect our environment be affected, for instance if they eat contaminated shellfish or swim in polluted water.
Activities that introduce waste into waterways
To avoid polluting our waterways, we need be aware of what activities introduce waste. These include washing vehicles and boats in yards and driveways, washing out paintbrushes, letting cattle wander through drains, washing spilt chemicals down the drain, and tipping away engine oil, paint thinners or the like. Not sure what’s safe? We have an adage: Only rain down the drain!
Ways to avoid common contaminants in our waterways
Some simple ways you can dispose of contaminants responsibly include washing cars on the lawn, and washing water-based paint or turps off brushes at an indoor sink such as the laundry tub. This means the waste products enter our sewerage system, which is designed to remove liquid wastes from kitchen sinks, basins, showers, washing machines and toilets. Wastewater is treated to remove harmful bacteria, solids and other pollutants so it can be disposed of either on land or at sea without harming our health or the environment.
We'll have more tips for you in coming weeks on what you can do at home, on the farm, or at your business to stop pollutants getting into drains.
Don’t hose house-washing or concrete-cleaning liquids – or any other chemicals – down a stormwater drain. They belong in the sewerage system.
Oil and water don’t mix
If you have used engine oil, ask your local garage if they accept it for recycling. Otherwise, put it in a sealed container and take it to one of the Council’s transfer stations for disposal with hazardous waste.
Keep it clean
To clean up any spills or dirt outdoors, don’t just wash the mess down the stormwater drain. Soak it up with rags, sand or newspaper, or sweep it up, for disposal with general rubbish.
On the farm
- Fence off streams from cattle.
- Plant riparian margins.
- Apply fertilizer and dairy effluent responsibly to control nitrate leaching into groundwater and streams
Have a Business Plan
Keeping chemicals out of our stormwater network is just as important at work as at home. Think “Only rain down the drain”. All other waste liquids belong in the sewerage system.
At workplaces such as industrial or automotive businesses where chemicals or cleaners are handled outdoors, have a plan to ensure they’re disposed of responsibly and lawfully. Recently we received a complaint when a mechanic was noticed allowing coolant to run into a street drain, leading to a local stream. Coolants and anti-freezes often use glycol as the primary active ingredient – the same toxin that sparked a worldwide scandal in the mid-1980s when it was added to some Austrian wines to make them sweeter and more full-bodied.
Bottom line: you wouldn’t want to drink it, so don’t put in our water
It won’t all come out in the wash
A carwash is a popular way to raise funds for your community group, sports team, or a good cause. Often, a business will help out by offering the use of a car park – but have you thought about where the soapy water will go?
If it enters the stormwater drain, it will flow untreated to our streams, rivers or the sea. Soap – even if it is biodegradable – is a pollutant that can diminish water quality, harm aquatic plants and animals, and affect people’s health. Carwash residue may also carry dirt, oil, and other automotive fluids.
So if you’re planning a carwash, look for a venue such as a field where contaminated water will be disposed of responsibly. Avoid sealed surfaces unless you can capture the wash-off as commercial
service station carwashes do. It’s just an extension of the principle of washing your own vehicle on the lawn instead of the driveway.