Question: how many litres of water to wash hair?
Answer: Toilet flush: 126 litres (two flushes per day; the rest of the time use grey water) Washing hands: 25.2 litres (12 times per day, on average) Brushing teeth: 5.6 litres (twice per day) Bath: 50 litres (1 half-full bath per week, which includes water for rinsing hair.