Thanks maizar- according to the description, the filters can be cleaned up to 100 times. I will look into activated charcoal filtration, thanks!
Remember gravity is your friend. As long as you have some space and a slope, you can put several filtration methods in series and get pristine water from the most disgusting sludge if it came to it.
I saw one idea of making a garden creek (basically an elongated half-pipe made from cement pond base along the side of a sloping block), with a bed of builder's sand (riverbed sand which has no salt in it) and water grasses growing through it. The grasses are picked occasionally and used as mulch or for compost (or discarded if you are worried about radioactive fallout at the time), the sand can be removed, washed and returned periodically. The thing is 10 or 20 meters long, or longer if you make it into a winding pattern, and water is continually cycled through it with a solar powered pump. It will maintain a body of water in a drinkable state by biodynamic filtration plus aeration, but not very good in a drought. The acidity/alkalinity will be perfect and it will be very sweet to drink. It's more for a farm situation where for example you are taking water from a creek or pond or river or some place that experiences run off from farms.
Nice idea if you have a good back and most people will have no idea what it does. When you want to take a drink of that, put it through your charcoal filter plus whatever else you have, but essentially those filters won't be overwhelmed and will last longer.
In one survivalism book I read there were accounts of people in recent wars surviving in beseiged cities (such as in Bosnia) using the above methods plus locally available chemical sanitization (household ammonia in this case). They were sneaking around at night and bringing back buckets of water from the river (which was heavily contaminated with cholera and untreated human waste). Fascinating reading actually and some very good points made, such as randomly using different routes, preparing hide-outs along the way and so forth.