State University Extension
Home Maintenance And Repair - 01500609
Distillation Water Treatment
Distillation is one of the oldest methods of water treatment and is
still in use today though not commonly as a home treatment method. It
can effectively remove many contaminants from drinking water, including
bacteria, inorganic and many organic compounds.
Note that home water treatment is considered only a temporary solution.
The best solutions to a contaminated drinking water problem are to
either end the practices causing the contamination or change water
sources. Distillation is a process that relies on evaporation to purify
water. Contaminated water is heated to form steam. Inorganic compounds
and large non-volatile organic molecules do not evaporate with the
water and are left behind. The steam then cools and condenses to form
Distillation is most effective in removing inorganic compounds such as
metals (iron and lead) and nitrate; hardness (calcium and magnesium);
and particulates from a contaminated water supply. The boiling process
also kills microorganisms such as bacteria and some viruses. The
effectiveness of distillation in removing organic compounds varies,
depending on such chemical characteristics of the organic compound as
solubility and boiling point. Organic compounds that boil at
temperatures greater than the boiling point of water (some pesticides)
can be effectively removed from the water. Organic compounds that boil
at temperatures lower than the boiling point of water (ex., benzene and
toluene) will be vaporized along with the water. If these harmful
compounds are not removed prior to condensation, they will
recontaminate the purified product.
Distillation units or stills generally consist of a boiling chamber,
where the water enters, is heated and vaporized; condensing coils or
chamber, where the water is cooled and converted back to liquid water;
and a storage tank for purified water. (Vis.
Distillation units are usually installed as point- of-use (POU)
systems. They are generally placed at the kitchen faucet and used to
purify water intended for (drinking and cooking purposes only. Stills
vary in size, depending on the amount of purified water they produce
The production rate varies from 3 to 11 gallons per day. Home stills
can be located on the counter or floor, or attached to the wall.
Models can be fully or partially automated, or manual. Some stills have
columns or volatile gas vents to eliminate organic chemicals with
boiling points lower than water, thus ensuring uncontaminated water.
Operation, Maintenance and Cost
As with all home water treatment systems, stills require some level of
regular maintenance to keep the unit operating properly. Unevaporated
pollutants remaining in the boiling chamber need to be regularly
flushed to the septic or sewer system. Even with regular removal of the
residual water that contains unevaporated pollutants, a calcium and
magnesium, scale will collect at the bottom of the boiling chamber.
This scale eventually needs to be removed, usually by hand scrubbing or
by an application of acid.
Heating water to form steam requires energy. This means that operating
costs for distillation units are generally higher than those of other
forms of home water treatment. The distillation process also removes
oxygen and some trace metals from water. Some people claim this leaves
the water tasting flat.
This information comes from Michigan State University Extension
bulletin WQ 22, Distillation for Home Water Treatment.
to main page
This information is for
educational purposes only. References to commercial products or trade
names does not imply endorsement by MSU Extension or bias against those
not mentioned. This information becomes public property upon
publication and may be printed verbatim with credit to MSU Extension.
Reprinting cannot be used to endorse or advertise a commercial product
MSU is an
employer. Michigan State University Extension programs and materials
are open to all without regard to race, color, national origin, gender,
gender identity, religion, age, height, weight, disability, political
beliefs, sexual orientation, marital status, family status or veteran
status. Issued in furtherance of MSU Extension work, acts of May 8 and
June 30, 1914, in cooperation with the U.S. Department of Agriculture.
Thomas G. Coon, Director, MSU Extension, East Lansing,MI 48824. This
information is for educational purposes only. Reference to commercial
products or trade names does not imply endorsement by MSU Extension or
bias against those not mentioned.
information.was reviewed as
of June 2008. For more information about the contents please
for webpage problems