Understanding the difference between wastewater and stormwater

Water treatment tank with wastewater

Most people’s water supply comes from one of two sources – wastewater or stormwater.

To deliver water to communities requires a deep understanding of wastewater and stormwater and the difference between them.

Each source has unique characteristics that require an expert level of knowledge when developing civil engineering solutions.

Water stream flowing out the underground tunnel

Stormwater and wastewater - the difference between the two

In short, stormwater, as the name suggests, is water that comes from rainfall. It can also come from melted ice and snow. Stormwater runs off hard surfaces like roofs, driveways and roads into stormwater drains. These drains feed into an underground network of pipes designed to flow into local waterways like creeks and rivers.

Wastewater, also its the name suggests, is used water from homes, factories and schools. Wastewater comes from sinks, laundries and bathrooms. According to Sydney Water, 99% of the material that goes down drains is water, which is why it is crucial to design infrastructure capable of recycling water.

Pit and Drainage Pumping Station with cloudy sky

Why stormwater and wastewater cannot mix

Stormwater is channelled into underground pipes and is then moved into local rivers, creeks and streams.

Wastewater undergoes a much more complex process. It undergoes various treatment processes to remove the waste within the water that is either fit to be channelled back into local waterways or reused in households, businesses, parks and agriculture as non-drinking water.

It is critical that wastewater and stormwater do not mix. When stormwater enters a wastewater system, it causes overflow of raw sewage. This is not only inconvenient for communities and councils but causes significant health concerns too.

Modern urban wastewater treatment plant.

Keeping the two separate requires skilled expertise in civil engineering

The eastern seaboard of Australia has witnessed some of the highest rainfall deciles in history. Floods have plagued many communities across NSW and Queensland. The effects of flooded wastewater systems are too devastating to imagine.

And let’s be honest – the word ‘flood’ (along with ‘epidemic’ and ‘pandemic’) is not a word we want to hear anytime soon.

Each system requires a unique approach, skilled civil engineering expertise and full-scale capability, specifically around the infrastructure requirements for stormwater, wastewater and ESC (erosion and sediment control), so if you need expert civil engineering, contact our team today.

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