JoshG said:
On the subject, There is a resevoir not too far from where I live in the hills. We found a stream running directly into the resevoir and the water looked very nice. We had a few gulps but didn't want to drink too much incase it had too much of something in it and may have had laxative effects etc... The stream was fast flowing directly from the hills, but further up the hills we noticed some of the stream beds were very orange, possibly large quantities of Iron in the water? Do you think it is safe to drink?
-Josh.
since there is no way that you could be sure that the water is safe no matter how clear and clean it looks without taking a sample and testing it scientifically , it is totally impossible for people on an internet forum to advice you whether your stream is safe to drink from.
if you are confident that there is no chemical pollution of the water source (which in this case you are not) then the simplest and most reliable method of purification is to boil the water.
if there is any chance that the water contains chemical contaminates then it should be avoided entirely, regardless of what the instructions that come with a water filter/purifier pump say that will not remove chemical contaminates.
for example if you take a pint of water and add salt so you have a saline solution then pump this though a filter/purifier into another glass you will find it is still a saline solution, the filter/pump hasnt removed any of the salt, nor could it have done (dont do this with your filter/purifier it will damage it)
the only pump system which can remove most chemicals in solution is a reverse osmosis pump (used on ships for creating drinking water from salt water) but the cost, weight, and effort involved in using one of these would defiantly put you off carrying one around and some chemicals would still get though, urea for example.