Earlier, the Indian Railway had decided to set up automatic coach washing plants at 10 major depots to save water required for cleaning trains. Reports inform that about 12,000 litres to 14,000 litres of water is used for cleaning one rake consisting of 22-24 coaches.
According to a PTI report, the automatic plant will require only 6000 litres to clean a rake out of which 4000 litres will be recycled water. As per the calculation, one depot will save 1,24,000 litres of water per day and 453 lakh litres per year once the plant is operational.
Source: http://www.railnews.in/railways-installs-automatic-train-washing-system-at-hazrat-nizamuddin-station-it-takes-8-minutes-to-wash-a-24-coach-rake/