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Chemical Technology • January 2015
Central softening
The issue of having calcium and magnesium in finished
drinking-water can be of importance not only for those water
suppliers that utilise desalination processes, but also for
the broader water industry internationally. The Global Water
Research Coalition, as representative of many water-related
research institutes worldwide, has prepared a review on the
reasons and criteria for softening and conditioning (Mons
et al
2007). It recommends that in addition to nutrition,
other health-related and other pertinent aspects should be
considered. Both very soft and very hard water can interact
with piping materials, whichmay negatively impact the water
quality and the integrity of the piping system. It is therefore
important that those other considerations, including the
optimal composition of piped drinking-water to prevent
corrosion and scaling, are taken into account.
In several countries, softening is sometimes applied
centrally (eg, Netherlands, Germany, Belgium, France,
United States). Point-of-entry (POE) softening at the indi-
vidual residence is the most frequently applied method of
softening. Central softening of drinking-water offers public
health and environmental benefits. Moreover, consumer
comfort is increased, and there are also several financial
benefits for the consumer.
Reasons for central softening include:
• reduced exposure to trace metals due to reduced
corrosion of plumbing in the distribution system and
household plumbing;
• reduced costs because of reduced consumption of
detergents and energy as well as lessened need to use
private softeners;
• fewer discharges to the environment (eg, less detergents,
Water production,
technical issues and economics
by Perialwar (Regu) Regunathan
Can calcium and magnesium (‘hardness’)
in drinking-water contribute to preventing
disease? Typical diets are often deficient
in calcium and magnesium, both
essential for strong bones and teeth,
and for cardiovascular function. There is
also evidence that ‘hard’ drinking-water
may be associated with reduced risks for
some diseases.