Question:
I am looking for some information on water purification systems. It is in regard to purifying surface water. everything that I came across on the web so far that was for sale was not very effective in this area. They only guaranteed that their machines worked in clear water. (Notice the touch of sarcasm) Are there any systems that will do an effective job in removing agricultural chemicals, metals and microbes?

Answer: The best portable water filter is the Katadyn unit. They are currently backordered everywhere so you need to place a order now. The Katadyn uses .2micron ceramic filters which will remove all harmful particulates except for viruses and chemicals(bad taste). Use an activated charcoal filter to remove chemicals and either distillation or UV filtering to remove viruses. There's just not a SINGLE magic method that will remove all bad particulates

Surface water in an urban area will need to be filtered through activated charcoal. If you expect to do this, don;t depend on the limited ammount of charcoal in microfilters. FIlter the water first through a full size charcoal filter (homemade or a water washer). As far as pathogens, you can treat with a halogen (iodine or chlorine) or use a microfilter, or a combination of the methods.

My choice would be to: 1) Allow the water to settle 2) pour through a coffee filter 3A) treat with 1 ppm iodine to kill viruses or 3B) Treat with 5ppm iodine (will kill anything but crypto). This will leave a iodine taste that should be removed by the charcoal filter. If it isn't this is a sign the charcoal filter has reached the end of it's life 4) Filter through a activated charcaol filter 5) Check for iodine taste 6) Filter though a microfilter with a carbon stage