Harvesting rainwater is an old practice and many water tanks that were used in the past for watering and house use can still be seen today in country houses.
It seems obvious that some uses of rainwater do not require the quality expected for drinkable water. This is the case for toilets or garden watering for instance.
Harvesting rainwater is an opportunity to get free water and to be autonomous in case of a drought or if there are restrictions.
With no prior treatment to make it drinkable, rainwater can have various purposes: W.C, garden watering, swimming pool filling up, cleaning, car washing.
However, it is not permitted to use rainwater for food purpose (drinking, preparation of food) or sanitary purposes (dishwasher, washing machine, shower, taps)