Brian, YOU CANNOT afford to compromise the safety of your water supply. Either boil it, or filter it. If you cannot do either of those then you must use chemical purification. The key to that is organisation. Set up a rolling cycle of purification. Mark/number your waterbottles so that you have one to drink, one spare and one purifying. Just to make the point: At Agincourt, for every English Man at Arms who was KIA or died of wounds received, Four died of water related illness.