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Woolies leads in using water wisely

1 August 2011

Retailer Woolworths has installed a water treatment system that uses water from a stream under its Cape Town head office to flush the toilets and run the building's car wash, entrance fountain and cooling towers for the air conditioning units.

The development will save the Cape Town municipality an estimated 27 375 000 litres of water a year or 75 000 litres of municipal water a day, while the retailer will benefit from a reduced water bill.

The underground water runs about 20 metres under Woolworths head office building in the centre of Cape Town. The water currently flows into the city's storm water system, and is eventually discharged into the sea. After much inquiry, the source of the underground stream is still somewhat of a mystery.

Woolworths' head of engineering services, Alex Kuzma, said the company had started investigating the project three years ago, and after consulting with the municipality and a range of experts had realised they could harvest the underground water, treat it, and use it instead of municipal water.

"Everyone wins – Woolworths, the City of Cape Town, residents, and importantly, the environment," Kuzma said in a statement last week. "This is part of our 'Good Business' journey, which helps to conserve natural resources and conduct business as responsibly as we can."

Reverse osmosis

The treated water is completely safe for use even though it will not be used as drinking water. To make the water safe for drinking, Woolworths has invested in a treatment plant that purifies the water using a number of steps including reverse osmosis.

Under that process, pressure pushes the underground water through a semi permeable membrane. The membrane, which is about as thick as cellophane tape, allows only the water to pass through, eliminating impurities or contaminates.

Drinking water will continue to be channelled separately into the building for the 2 000 people who occupy it daily. Once the treated water has been used, it will exit the building into the municipal waste water system.

"The conservation and management of water is a major focus area of our Good business journey programme, as it should be in a country where water is a scarce resource," said Kuzma.

Woolworths' Good business journey is a comprehensive plan to make a difference in in the areas of transformation, social development, the environment and climate change.

SAinfo reporter