The Citrus County Health Department issued a caution to area residents Friday, warning that some people have been posing as health officials and have been using "scare tactics" to sell water treatment systems. The health department suggests that anyone approached by someone claiming to be from the office should ask for identification. Also, officials say because water in this area flows through limestone, it is normal for the water to be hard and contain minerals. These require treatment only if the elements are present in high concentrations and cause taste or odor problems. Central water systems already are required by law to monitor their water quality regularly.