Originally Posted by cyccommute

Now your are being really silly and not a small bit ignorant of what your filter does...and does not...do. Your filter will remove organism that can make you sick but it does nothing to remove other toxic contaminants. The grid that you pooh pooh can remove those contaminants because it can do things that you can't. There are streams within the mineral belt of Colorado that you should drink from because of mine drainage and if you don't have knowledge of what's upstream, you can be ingesting several toxic metals that are natural as all get out but hardly good for you.

Further east you are going to run across water that may contain other chemicals that aren't good for you either and for which your filter is useless.

Gramatically, 'their' posessive is different from 'there' as is a place.