Treated Waste Water being utilised in Cape Town
[For convenience, this article is repeated from City of Cape Town website]
City makes treated water available to keep industry going
07 December 2017
Statement by the City’s Executive Mayor, Patricia de Lille
Today I visited the Potsdam Wastewater Treatment Works where the City of Cape Town is making treated wastewater available to businesses dependent on water.
By using treated water, businesses are reducing their use and reliance on drinking water. This is one of many ways in which the City and businesses are adapting to water scarcity and stretching drinking water supplies for essential use.
Treated effluent is the final product from the treatment of sewers which meets the general authorisation standard for discharge into the rivers for irrigation. It is further filtered and pumped into the network for further use. This network is separate from the potable water reticulation network which supplies drinking water.
Although many residents and businesses have done well to reduce their consumption of water, we are still not saving enough water to avoid Day Zero. If dam levels reach 13,5% the City will be forced to turn off most taps and residents will have to collect water daily from collection sites across the city.
The City remains steadfast in its commitment to creating an enabling environment for businesses to thrive and to doing everything we can to bring additional sources of water on stream.
The City is using and reusing every drop of water we can. Treated wastewater is made available to businesses.
The City is also using treated wastewater to clear stormwater drains and unblock sewer pipelines as well as at parks and at some Fire and Rescue Service facilities.
More than 200 businesses are using treated effluent from permanent pipelines, while 150 businesses are collecting treated effluent at wastewater treatment works and draw-off points. These include stormwater and sewer cleaning companies, construction companies, painting companies, boat-cleaning companies, car washes, movie production companies, the Cape Town International Airport, outdoor improvement companies, manufacturing companies and drilling companies. They are all using treated effluent in their operations.
Construction-related activities where treated wastewater can be used include:
• Sub-base material for reinstating asphalt as per City specification
• Construction of road sub-base layers not sensitive to water quality requirement
• All construction site dust control
• Washing off of retarder from concrete
• Terrace works compaction
• Earthworks compaction
• Trench backfilling
• Cleaning of construction equipment
• Spraying on compacted surfaces
Currently the City has made available seven treated water draw-off points to businesses – including the two points in Goodwood and Thornton which opened this week.
The City has made R2,4 million available to make 24 treated water draw-off points available to businesses.
Using treated wastewater on site also makes financial sense because at R5,30 (including VAT) per kilolitre (1 000 litres) it is much cheaper than using potable water. More importantly, using treated wastewater helps Cape Town to conserve the potable water supply.