This document discusses different methods for treating and purifying water on both large and small scales. It addresses hardness in water and various processes for removing both temporary and permanent hardness. Methods for purifying water naturally or artificially on a large scale include storage, filtration using slow sand or rapid sand filters, and disinfection through chlorination. Purification on a small scale includes boiling, chemical disinfection using various chlorine sources, and filtration. Specific processes for disinfecting wells are also outlined.