Letter Re: Seeking Advice on Rainwater Catchment and Filtration

Sir:
I am an environmental engineer. You posted a letter that inquired as to whether a ceramic water filter was capable of removing chemicals that leach from plastic containers. The answer is no, a ceramic microfilter will not remove the chemicals. Aside from reverse osmosis, which requires pressures that are too high [for treating large volumes of water] in a survival situation, the best choice for treating water with chemical contaminants is to use activated carbon. Activated carbon is very cheap, widely used by municipal water treatment plants, and is highly effective at removing many organic contaminants (through adsorption). I am not sue about the specific compounds leached from plastic containers, as some compounds are not removed well by activated carbon. In general though I would highly recommend it. A simple web search for activated carbon will yield some suppliers. Please note that the starting material the activated carbon is made from will effect its properties, such as pore size. A good water purification strategy is to chlorinate the water, filter through the microfilter, and then filter it through activated carbon. If the water is very dirty I suggest chlorinating after microfiltration but before activated carbon filtration, as the chlorine can react with compounds in the water forming harmful disinfection byproducts. The activated carbon will remove the chlorine also. I have a Katadyn hand held ceramic microfilter that also has an activated carbon cartridge accessory, but it is a bit expensive. - Jorge