I read that it is perfectly fine to be drinking collected rain water as long as the air and the container are not polluted. However, would it be possible for a civilization to

  1. survive and
  2. live healthy

while only collecting rain water?

I am mostly concerned by these two factors:

  1. Rain water usually has a pH value of 5 to 5.5 whereas tap water has a pH value of around 6.5 to 8.5.
  2. Rain water is almost pure H₂O but tap water contains lots of minerals like calcium and magnesium, which are quite important for the human body to work properly.

Thus, would it be possible to only drink rain water? Would one have to process it first to add certain minerals?

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  • 3
    $\begingroup$ There have been and there still are cities in arid regions where almost all drinking water is rain water collected into enormous cisterns and reservoirs. (And rainwater is pure water immediately after collection. After sitting in a cistern for a while, it is no longer so pure.) $\endgroup$
    – AlexP
    Nov 23 at 18:04
  • 2
    $\begingroup$ Not only is it healthy - it will protect you from the international Communist conspiracy to sap and impurify all of our precious bodily fluids. $\endgroup$ Nov 23 at 18:44
  • $\begingroup$ Would you please be more specific with what you mean by "Rain water" almost all fresh water has been rain water in the not too distant past. What does it have to touch for you to stop qualifying it as rainwater and be classified as something else? $\endgroup$
    – Mathaddict
    Nov 23 at 19:19
  • 1
    $\begingroup$ @Mathaddict I mean water that is collected directly from the sky as opposed to water obtained from rivers, lakes, sources, wells etc. $\endgroup$
    – Itschotsch
    Nov 23 at 22:12

Rain water will collect minerals from the places where it is stored, usually a room dug underground in rocks and covered with some waterproof substance, therefore it will never be equivalent to demineralized water.

As a matter of fact, many places have relied on harvesting rain water as only way to get fresh water.

Personally I have grown up in such place, like my parents, grandparents and grand-grandparents did, where the only water we got during summer was the winter rain harvested from the roofs in an underground chamber, coated and painted with lime. It had a very light taste and very little minerals, and the lime had the function of balancing the pH and also be blandly disinfecting. Some people even added a live eel in the chamber, to get rid of any major residual. The only time we didn't use it was in the summer following Chernobyl, for obvious reasons.

As comparison, once it was economically feasible to dig a well, the water there was very rich in calcium carbonate and much more "heavy" to the taste.


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