This weekend we went "pole camping". A pole camp site (dutch link only) is a camp site offered by the departments of forestry in the Netherlands and Belgium. It is very basic. What is offered is a handpump providing ground water, a fire place and and a place for three trekking tents usually some where along hiking trails in both the Netherlands and Belgium.
At the pole-camp site we stayed at this weekend, the ground water looked very clear. Directly from the source you could see right through. However, upon cooking the water turned brown with a fatty film floating on top. The longer the water boiled, the more brown the water became.
What makes clear ground water turns brown upon cooking and more importantly can you still consume it after thoroughly cooking it?