In the preamble of the Department of
Health of South Africa (2006) regulations that can be
www.doh.gov.za/department/dir_foodcontr.html are the
following definitions for “prepared water”
“prepared water” means bottled water that has undergone
any treatment acceptable for bottled waters and may
originate from any type of water supply, e.g. distilled
tap water, tap water with added minerals”
Dept of Health of South Africa. 2006. Regulations relating
to all bottled waters. Foodstuffs, Cosmetics and
Disinfectants Act, 1972 (Act no. 54 of 1972) No. R. 718.
28 July 2006
Fundamentally, all water packed into sealed containers and
sold for human consumption that does not contain sugars,
flavourings (etc) are classified as bottled water. This
includes carbonated, natural, mineral, spring and prepared
water. Let us examine the prepared waters in more detail.
Prepared water is defined as bottled water that has
undergone treatment(s) acceptable for bottled waters and
may originate from any type of water supply such as
environmental sources and municipal sources.
How can prepared water be processed? Legally, prepared
waters may be subjected to any anti-microbial treatment
and any treatments that modify the physicochemical
characteristics of the original water as long as the end
result comply with all the legal provisions for all
The labelling of prepared waters must state that it is
prepared water, the treatment methods declared as well as
the phrase “from a public or private distribution system”
if the water was indeed supplied by such a source. This
legislation is very much in line with overseas thinking,
such as in Canada. Keep in mind that prepared water can
originate from any source or combination of sources, such
as springs, wells, reservoirs, icebergs, glaciers, rivers
and lakes. The difference between prepared water and
natural water is solely that prepared water can be treated
and modified by various means. All these treated waters
are grouped in one category. Natural water must be potable
at source whereas prepared water is treated to ensure its
Due to the various sources of prepared water, quality
regulations include the absence of heavy metals and
classified toxic compounds such as mercury, cyanide and
pesticides. But then again, these requirements also
pertain to natural mineral water.
Which processes are traditionally used in prepared waters
for its purification?
Distillation can be used to purify water. However,
distillation is expensive as water needs to be boiled and
then condensed, collected and stored. It is noteworthy
that chemicals such as some pesticides with a low boiling
point will be distilled into the distilled water.
Distilled water can also be very acidic (low pH).
Distilled water is often called “hungry” water because of
the lack of mineral content. It lacks oxygen and minerals
and has a flat taste, which is why it is mostly limited to
industrial use. I believe that drinking distilled water is
unhealthy as it may lead to mineral depletion of your
In ion exchange systems, water percolates through
bead-like spherical resin materials (ion-exchange resins).
Ions in the water are exchanged for other ions fixed to
beads. The two most common ion-exchange methods are
softening and deionisation. Softening is used primarily as
a pretreatment method to reduce water hardness prior to
reverse osmosis (RO) processing. The softeners contain
beads that exchange two sodium ions for every calcium or
magnesium ion removed from the "softened" water.
Deionisation beads exchange either hydrogen ions for
cations or hydroxyl ions for anions. The cation exchange
resins exchange a hydrogen ion for any cations they
encounter (e.g., Na+, Ca++, Al+++). Similarly, the anion
exchange resins exchange a hydroxyl ion for any anions
(e.g., Cl-). The hydrogen ion from the cation exchanger
unites with the hydroxyl ion of the anion exchanger to
form pure water. The resin must be "regenerated" once it
has exchanged all its hydrogen and/or hydroxyl ions for
charged contaminants in the water. This regeneration
reverses the purification process, replacing the
contaminants bound to the resins with hydrogen and
Deionisation can be an important component of a total
water purification system when used in combination with
other methods such as RO, filtration and carbon
adsorption. Deionisation systems effectively remove ions,
but they do not effectively remove most organics or micro-
organisms. Micro-organisms unfortunately can attach to the
resins, providing a culture media for rapid bacterial
growth and subsequent contamination.
Carbon adsorption (or carbon filtration) is a widely used
method of home water treatment because of its ability to
improve water by removing disagreeable tastes and odors,
including chlorine. Activated carbon effectively removes
many chemicals and gases, and in some cases it can be
effective against microorganisms. However, generally, it
will not affect total dissolved solids, hardness, or heavy
metals. Only a few carbon filter systems have been
certified for the removal of lead, asbestos, cysts, and
coliform organisms. Activated carbon is created from a
variety of carbon-based materials in a high-temperature
process that creates a matrix of millions of microscopic
pores and crevices. Half a kilogram of activated carbon
may provide between 24 and 60 hectares of surface area!
The pores trap microscopic particles and large organic
molecules, while the activated surface areas cling to, or
adsorb, small organic molecules. Carbon also removes free
chlorine and protects other purification media in the
system that may be sensitive to an oxidant such as
chlorine. Carbon is usually used in combination with other
treatment processes. The placement of carbon in relation
to other components is an important consideration in the
design of a water purification system.
Filtration is not unique to processed water as filtration
is widely used in the natural water bottling processes.
However, filter systems for processed water may also
contain stages and types of cartridges that remove certain
mineral elements, e.g. nanofilters, ultra filtration,
desalination filtration, charcoal filtration and more.
Depth filters are usually used as prefilters as they can
economically remove up to 98% of suspended solids. Next in
line are the surface filters that can remove 99,99% of
suspended solids. Lastly, microfilters are used to remove
traces of particles and microbes. The above microporous
filters remove particles according to pore size. By
contrast, an ultrafiltration membrane functions as a
molecular sieve, separating dissolved molecules on the
basis of size. Ultrafilters remove most particles,
pyrogens (dead bacteria), and produces the highest quality
water for the least amount of energy.
Many large processors use reverse osmosis membranes to
remove salts, chlorine and impurities. They then add a
standardised mineral salt solution to the RO water
(re-mineralise). They can therefore manipulate and control
the taste of the prepared water very closely. Quality is
closely monitored and only high purity salts should be
used. The consumer can then expect a standardised,
specific taste at all times. RO is the most economical
method of removing 90-99% of all contaminants. The pore
structure of RO membranes is much tighter than the
ultrafiltration membranes, and can remove particles,
bacteria, pyrogens and organics greater than 300daltons
molecular weight. RO is highly effective in removing
several impurities from water such as total dissolved
solids (TDS), turbidity, asbestos, radioactive isotopes,
lead, heavy metals and dissolved organics (e.g.
Ozonation can be successfully used to oxidize metal salts
such as iron and manganese and to precipitate them. After
precipitation, the water must be filtered to ensure the
removal of these salts. These specific precipitates are
dark coloured, typically rusty colour. Ozonation is mostly
used for disinfection purposes. Residues of ozone in
bottled water leave a metallic taste. However, this taste
will dissipate after a few days in storage as ozone is
Pasteurisation may be used to remove vegetative
micro-organisms from water. Pasteurisation will not
sterilize the water, and spore formers such as Bacillus,
if present, may multiply after bottling and form floaters.
Pasteurisation will be effective against the majority of
pathogens. UV radiation is another means of disinfecting
clear water. A UV lamp that generates both 185 nm and 254
nm wavelengths will be able to decrease the total organic
carbon (TOC) levels to 5ppb through photo-oxidation.
Because each purification technology removes a specific
type of contaminant, a well designed water purification
system uses a combination of technologies to achieve a
specific water quality.
The following is required to be indicated on the label:
The name of the product: “prepared water”
The disinfection or treatment method used
The analytical composition in milligrams per litre
in the same order as provided in the regulation.
Descriptors as “still” or “non-carbonated”
and “sparkling” or “carbonated”
The phrase “from a public or private distribution
system” if the prepared water was supplied by a public
or private tap-water distribution system.