Distillation for Well Water


Distillation unit

Distillation for well water under the sink unit.

Distillation for well water is an option for treatment.  One of the oldest, and yet still very effective methods of purifying water is distillation. It is based on a very simple principle. Water in a liquid state is the “universal” solvent, meaning it dissolves and carries most everything it contacts. So well water can carry all manner of contaminants – inorganic compounds (like iron, arsenic, copper, fluoride, arsenic), organic compounds (like some pesticides), and microorganisms (introduced from plant material, leaking septic systems, or surface water intrusion). However, water in a gaseous state, carries nothing. Simply put, distillation uses heat to convert (boil) the well water to vapour or steam, which then passes over cooling coils and condenses.  The resulting fluid is nearly pure water.

Removal rates for inorganics and total dissolved solids can range from 95-99%. Very effective!  Distillation will not be nearly as effective, however, for some organics that have a boiling point close to that of water, which is why it’s a good idea to add an activated carbon filter between the condensing coil and the reservoir for a more complete system. The boiling process effectively inactivates any microorganisms such as bacteria, viruses, or protozoan cysts.  A note of caution here – the water may become re-contaminated if bacteria are inadvertently introduced through the spigot.

Given their energy usage, distillers are better suited to point-of-use applications. That is, using it only as a supply for water used for cooking and drinking.  This will require the installation of a dedicated tap. Since not all the household water is being treated,  nuisance contaminants in the water like hardness minerals and iron or iron bacteria and even hydrogen sulfide ( the culprit where water smells of rotten eggs) will still be present and can damage the household plumbing or stain fixtures.

In some distillers, the intake water will be run through the cooling coils. In this instance, it may take from 4 to 7 gallons of water just to produce 1 gallon of consumable water.  With water shortages impacting much of the USA, this wastage can be a serious consideration.

From a maintenance perspective, it is important to clean the distiller regularly.  Contaminants and hardness minerals, in particular, form a residue or scale on the unit which can reduce efficiency and drive increased energy usage. In fact, if your water is particularly hard, you may want to purchase a water softener too. If your unit incorporates an activated carbon filter, this will need to be replaced periodically.

Simple in principle and simple in operation and maintenance, distillation can solve many water contamination issues.  Simply put, it’s an oldie but a goodie – although not practical for whole-home treatment.