So I admit I really don't know much about radiation and how it would affect something like water especially over time. I find it very odd how every water source I have found and jumped into is hot yet I can stand out in the middle of a rain storm without a care (well other than the normal stuff trying to kill me). I find it even stranger that I can not build anything to catch this clean water source so that makes me wonder is the rain suppose to be radioactive? This would be bad if caught outside but would it really be much different than that fog thunderstorm thing that happens? And if it isn't suppose to be hot then why is no one taking advantage of this. Another question is how can the ground water be clean wouldn't that have been affected as well?

There doesn't seem to be difference to dirty water and purified water for settlements. For example it's not possible to build the water purifier in the farm settlement?? Only dirty water machine.

Well you need a water source in order to build a water purifier. You can build one at sanctuary (river) and the castle already comes with one in the ocean. Not sure which farm you mean but the one I can think of doesn't have a river, ocean, or lake inside the building borders. The question I am most curious about is why is the rain not radioactive when every other natural water source is.

Water have to contain radioactive particles to be radioactive. Rain is condensed water vapor therefore unless wind or something else did not raise radioactive particles in to the atmosphere, it should not be radioactive.

Nuclear explosion of course puts huge amount of radioactive particles in to atmosphere but perhaps 200 years after explosions all or most of the particles fell already to the ground ...in the form of radioactive "fallout" ...therefore in Fallout, radioactive fallout is already over

https://en.wikipedia.org/wiki/Nuclear_fallout

In Fallout 3, all the water was radioactive and every single tiny puddle gave you rads. In reality stepping in small puddle, even if the water was radioactive, would only give you a trace exposure. In Fallout 4, most of the small puddles and damp sewers don't give you rads, just swimming in large rivers or the sea. Rain just after a nuclear detonation is black and massively contaminated with radioactive dirt that is shot way up into the atmosphere. However, as mentioned, it's been 200 years so the exposure you get from rainfall is probably too small to be detectable. Even the radioactive storms only give about 20 rads over time. I think it makes sense.

the length of time that has passed since the bombs fell should be enough to have cleansed most of the surface rads from all the area's outside the primary blast zones most water sources especially those protected from direct exposure to the blasts such as wells should be rad free as well as rain even the smallest of radioactive particles will quickly precipitate out of rain they are very heavy and don't stay airborne for long so yeah the left over rads in this game are just a that a game effect giving all of us something else to worry about hehe

Radiation also doesn't turn scorpions into giant monsters.

Science!

It's just so crazy!

Well well well, that's odd too, because whether it's a water pump or a motor driven pump that shouldn't make any difference as to location. But it's still odd that water in the settlement menu is not distinguished WHEN there are both dirty pumps and purifier pumps adding to that number.

Maybe I don't understand what you mean. I don't think the hand pump well water supply is dirty which is part of my confusion. Also even though the tool tip says water purifier I am not sure if it really is doing that as I don't think we can drink from it but then again I haven't really tried. I was under the impression that they all did the same thing but just in different sized returns.

Now that I know it is normal for the rain to be rad free I really don't understand why no one takes advantage of that. It would be so easy to do and far more efficient than a motor driven machine for which fuel is suppose to be in very short supply. I think that is really my biggest hang up with this Fallout game and settlement building is that the resource issue is all but ignored.