From the blog
However, there is also a lot that chlorination can't do. Just because it kills a wide range of microorganisms doesn't mean that the water is completely clean after that. It can't actually remove anything from the water, such as chemicals or even particles of sand. All of these can degrade water quality, even if they are far less immediately hazardous than bacteria, so depending on local water conditions, a filter may still be needed.
Water Filtration and Chlorination
Gravity Water Filters are the most viable means of supplying yourself with clean water after a disaster because they require no running water or electricity to work. With two stainless steel chambers stacked one above the other and upright “candle” filter cartridges.