Many locations can collect rainwater for communal needs.
RaHa gives rainwater harvesting systems of capacity either half the collectible rainwater in the month with the highest precipitation or double the water demand, the lower of the two.
The house above, for example, has a rainfall collection area of 190 square metres –– note that the area is 19m x 10m [NOT 19m x 14m (7m + 7m)]. If the house is located where precipitation report below is about, then April is the month when the largest amount of rain can be collected from the roof –– precipitation in April is 243mm –– therefore, collectible rainwater to be considered for this house is 46170L (190 x 243).
Half of the collectible rainwater (46170L) is 23085L.
Since 4 people stay in the house, water demand is 12000L per month; going by WHO recommendation regarding water demands.
Two times the demand (12000L) is 24000L.
The lower of the two (half of the collectible rainwater & doubled water demand) is 23085 L therefore, RaHa will give a 23,000 L rainwater harvesting system to residents of the house –– RaHa will retrofit a 23,000 L rainwater harvesting system to this house.
The residents will agree to use the water together with villagers around the house, so that there is no waste. To avoid waste, the residents will recruit 4 more water users every 3 months after the construction of the system.