Seawater flushing: Capetonians willing to pay extra for sustainable sanitation.
Image: Jaman Asad/Unsplash
Capetonians are prepared to pay up to 10% extra on their water bills to flush their toilets with salt water as long as it does not smell or stain.
This is according to research conducted by the University of Cape Town (UCT). The research is titled "Feasibility of using seawater to flush toilets in the African context" and aims to investigate the use of seawater in Cape Town toilets.
In the study commissioned by South Africa's Water Research Commission, Teboho Mofokeng, a lecturer in water engineering at UCT and co-author of the report, investigated the country's water management and reuse.
The researchers surveyed 239 individuals to determine whether they would prefer using saltwater or recycled water for flushing toilets instead of continuing to use drinking water, even if it meant paying more. They also explored participants' opinions on the disposal of toilet effluent into the sea.
Mofokeng added that 20-30% of the city's potable water supply to houses is used to flush toilets.
Another issue was that wastewater from several Cape Town neighbourhoods, as well as the coastal cities of Durban and Gqeberha, was released into the sea with no treatment to eliminate hazardous microorganisms.
"The third problem is that as demand for housing grows, so does the need for water and sanitation. When more and more wastewater is discharged into the sea, it is a lost opportunity to keep the water within the urban water management system, and use it again," she said.
However, when new housing complexes are connected to the water supply network, alternatives to flushing toilets with drinking water might be discussed. One possibility is seawater. Another option would be recycled water, added Mofokeng.
"Toilet water could be treated to remove harmful bacteria and reused for flushing. This would need a closed water system for flushing toilets. It would eliminate the current loss of drinking water flushed down toilets and then discharged into the sea."
However, seawater flushing has several downsides. It would be necessary to put up a duplicate network, with one network of water pipes for drinking water and another for toilet flushing water supply. This would imply that both new and old water systems would be installed or replaced with systems having a duplicate pipe network.
"Usually water supply networks use concrete, steel or plastic pipes. But because seawater corrodes, plastic pipes will be needed for the seawater flushing pipe network. Plastic manufacturing and the raw materials needed have a significant impact on the environment. On the other hand, steel or concrete pipes would need to be replaced more frequently than plastic pipes," added Mofokeng.
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