A £7m recycling plant was opened last week by environment secretary Caroline Spelman on the Stratford site of a former sewage works. It produces 570,000 litres of recycled water a day, pumped into the park's pipe network.
It will save parks staff using up to 83 Olympic-size swimming pools worth of drinking water every year, said the Olympic Delivery Authority. This will help it far exceed its 40 per cent water-efficiency target.
Water from the plant, which has a green roof, will also be used to flush toilets.
Martin Baggs, chief executive of co-funder Thames Water, explained: "This system provides water of different standards for different purposes. Water is a precious resource that we must use wisely."