Woolworths has tapped into an underground water supply to meet some of its daily water needs. Woolworths installed a water treatment system that uses water under their Cape Town Head Office building to flush toilets, run the building's car wash, the fountain outside the building and the cooling towers for the air conditioning units. This will save the Cape Town municipality an estimated 27.37 mln liters of water a year or 75,000 liters of municipal water a day conserved by Woolworths. In addition, the retailer's water bill will be reduced. The treated water is completely safe for use even though it will not be used as drinking water.