Reverse osmosis is best at removing dissolved substances including sodium, calcium, iron, manganese, nitrates, lead, other heavy metals and dissolved organics. The biggest draw back with reverse osmosis units is their initial cost, on-going maintenance costs and the small amount of purified water produced. Distillation Units Distillation Units operate on the principal of condensing water vapors generated from boiling water. The contaminants remain in the pot, producing relatively clean water in the distillate. Home distillers are effective at removing salts, inorganic ions and hardness.
Distillers actually increase the concentration of trace organic contaminants in the distillation.
Also, distillers need frequent cleaning if used with hard water. The ion exchange resins must be regenerated periodically, a process which fl ushes out calcium ions and makes the sodium form, so the resin can be used.