The smallest of all water supply types, whether public or private, is the individual system for a single user. This is usually a private well, because the minimum treatment for a surface supply is often more trouble than is worthwhile: chemical disinfection and fine-filtration to remove parasites are unavoidable, and the addition of flocculants and the holding time needed to promote coagulation may also be needed. We usually recommend that well waters be chlorinated (for disinfection) and that will also change any iron or sulfide to filterable particles which are easy to remove. Well water often requires softening or conditioning (removal or reduction of hardness), and that can also remove small to moderate amounts of iron and manganese by ion exchange.