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Comment by Lendal | Hacker News Reader

Because we don't drink rainwater.

In the Boston area, our water comes from the Quabbin Reservoir. That's largely fed by rain, as far as I am aware. How much PFAS actually gets filtered out? Probably not much.

You can actually easily find this information online [0]

> PFAS compounds, used since the 1940s for many purposes, from stain and waterproofing to firefighting, continue to be a concern. Tests of MWRA water show only trace amounts of these compounds, too small to be quantified, and well below the state standard of 20 parts per trillion. MWRA results are also well below recently proposed EPA standards.

[0] https://www.mwra.com/annual/waterreport/2022results/PDFS/Bos...

A lot of the world most certainly does, especially in rural areas that are not connected to water treatment plants. Bore water tends to be hard, so humans stick to the rain water when we can get it.

What are we drinking then ?

Spring water or water coming from water treatment plants, both of them are very dissimilar to rain water

All of which ultimately comes from rainwater.

Ultimately all water comes from the creation of the earth, which in turn got it from space. The ultimate origin is not very useful.

If we just want the first step before treatment plants, it depend on location. Generally it is what ever water that is cleanest and cheapest, usually lakes and rivers with the best connection and high flow of ground water. Ground water tend to be highly filtered which lowers the amount of treatment that treatment plants has to do.

Rainwater collection is usually not used for drinking water given the high amount of pollution. It can be used in industry/agriculture, or as backup for areas where the ground water is severely limited.

Of course, and most of it comes from sea water, it doesn't mean you can drink sea water

There is a substantial level of natural filtration between rainwater and springwater, so they are not equivalent.

Groundwater, water from wells.

In a lot of places drinking water is pumped from open air aquifiers(a lake basically) so presumably it contains everything rain does, since it doesn't go through the rock layers.

Which is also polluted with pesticides and other agricultural pollutants.

Not all wells, mainly those that are in aquafier catchments that include heavy PFA sites and agricultural runoffs, etc.

Airports are notorious sources, PFA's were used in fire fighting foams for a decade or more (depending on global location).

We don't but are we alone on this planet?

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