Distilled water is water that has many of
its impurities removed through distillation.
Distillation involves boiling the water and then condensing
the steam into a clean container. Where exceptionally high purity
water is required, double distilled water is used.
water is preferable to tap water for use in automotive cooling systems. The minerals and ions
typically found in tap water can be corrosive to internal engine components,
and can cause a more rapid depletion of the anti-corrosion additives found in
most antifreeze formulations.
Distilled water is also preferable to tap water for use in model steam engine boilers and model
engines of other types. Mineral build-up resulting from the use of tap
water in model boilers can severely reduce the efficiency of the boilers if run
for long periods. This build-up is known as boiler scale.
is a measure of the ability of water to pass an electrical current.
Conductivity in water is affected by the presence of inorganic dissolved solids
such as chloride, nitrate, sulfate, and phosphate anions (ions that carry a
negative charge) or sodium, magnesium, calcium, iron, and aluminum cations
(ions that carry a positive charge).
Electrical conductivity or specific
conductance is the reciprocal of electrical resistivity.
is measured in micromhos per centimeter (µmhos/cm) or microsiemens per
centimeter (µs/cm). Distilled water has a conductivity in the range of 0.5 to 3
µmhos/cm. Industrial waters can range as high as 10,000 µmhos/cm.
The conductivity of water from various sources:
Absolute pure water - 0.055 µS/cm
Distilled water - 0.5
Mountain water - 1.0
Most drinking water sources
- 500 to 800 µS/cm
Sea water - 56 mS/cm
Max for potable water
- 1055 µS/cm
conductivity of water samples is used as an indicator of how salt-free,
ion-free, or impurity-free the sample is; the purer the water, the lower the
conductivity (the higher the resistivity).