Reverse osmosis and mineral water

Another issue in the global bottled water industry, that particularly affects consumers, is the fact that there are distinct types of bottled water on sale. The main types are mineral water and prepared water.

Natural mineral water is internationally defined as water sourced from a natural source and which has undergone no treatment that alters its mineral content.According to the South African Bottled Water Association (SANBWA) prepared water on the other hand is ‘stripped of all its chemical and mineral contents and impurities’ and can be sourced from either municipal sources or natural sourcesInternationally, regulations require that bottled water labels must indicate the source of the water, the processes it was prepared by and the mineral content of the water, in order to afford buyers a true reflection of the product they are paying for.In Namibia, the issue is, predictably, muddled. Labels are often out of tune with international guidelines and standards. Some labels state contradictory information e.g stating that the water is ‘mineral’ water but also stating that the water has undergone reverse osmosis, which means that it is in face ‘prepared water.’Charlotte Metcalf, a water expert at SANBWA, said that ‘once a bottler chemically alters the water it cannot be categorised as natural mineral water and has to be called prepared water.’Metcalf added that prepared water is ‘legitimate in SA’. She added however that the ‘market leader in SA, however add some minerals back to give it a more balanced composition and appealing taste.’The South African regulations relating to all bottled waters, defines natural mineral water as ‘bottled natural water which contains mineral salts in various proportions and which is characterised by the presence of trace elements and other substances such as calcium, magnesium, sodium and potassium’The regulations furthermore explain that ‘natural water’ ‘means bottled water derived from an underground formation which has not been modified and has not undergone treatment …’Although there is some international debate on whether prepared water is essentially tap water with a fancy label on it, SANBWA states that ‘prepared water is perfectly safe and a legitimate bottled water category …’ and reiterated that prepared water is ‘never untreated tap water.’ But without regulations and monitoring in Namibia, it is unclear whether those standards are upheld locally.In South Africa, it is ‘illegal for anyone to put tap water in a bottle and label it as spring water or natural mineral water.’ The debate on mineralsInternationally, there is some debate regarding the health effects of water that contains no or very little minerals. The South African National Bottled Water Association (SANBWA) however advocates that mineral content is ‘not an indication of quality.’Charlotte Metcalf, SANBWA’s water expert, added that the quantity of minerals contained in water ‘has a direct influence on the taste, and depending on where you grew up or, lived long enough to get used to the taste of the water, that is what you will prefer.’ Mineral content is measured, and stated on the labels, as the total dissolved solids (TDS) found in water. TDS is the total amount of dissolved solids in milligram per litre of water. A high measure of TDS usually indicates the water has not been chemically changed, and a low, or zero TDS means that the water has no mineral, or very little, mineral content.’The taste of water reflects different concentrations of minerals and trace elements,’ Gleick confirms in his report.He adds that it is this ‘taste factor’ on which many in the industry depend to sell their product.’Highly subjective preferences for taste and flavour in water help drive the market for bottled water. Water has different flavours and tastes depending on its origin, type and duration of storage, treatment and method of delivery,’ he writes.SANBWA reported that TDS values depend on the source of water, and can range from naturally low to very high.’Generally, our bottled waters in SA are below 500 ml/l which, in international terms is described as low mineralised ground waters.’ Internationally, it is also accepted that water with a mineral content of 250 ml/l or higher, can be labelled as mineral water. Anything lower than that, can no longer be classified as mineral water.On the other side of the mineral coin however, there are some questions about water containing very low or no minerals.A draft document written by Dr Frantisek Kozisek for the World Health Organisation (WHO), titled ‘Health risks from drinking de-mineralised water’ defines de-mineralised water as ‘water almost completely free of dissolved minerals as a result of distillation, de-ionisation, membrane filtrations (reverse osmosis or nano- filtration).’According to Kozisek, research has indicated that a reduced intake of minerals from drinking de-mineralised water could potentially result in the ‘dilution of the electrolytes dissolved in a person’s body water’.A concern Kozisek notes about drinking de-mineralised water, noted in the report, is the ‘practically zero calcium and magnesium intake from low-mineral water.’Kozisek adds that although drinking water, with some rare exceptions, is not the major source of essential elements for humans, its contribution may be important for several reasons. ‘The modern diet of many people may not be an adequate source of minerals and micro-elements.’He added that in a ‘case of borderline deficiency of a given element, even the relatively low intake of the element with drinking water may play a relevant protective role.’Dr Gleick wrote that ‘users should not assume that the purity of bottled water is adequately protected, regulated or monitored. Many bottlers themselves do most of the sampling and testing, which opens the door to fraud, misreporting and inadequate protection.’ His words reflect the reality in Namibia. What really mattersThe debate around mineral content does not address the issue of disinfection, however.Menge added that it is important to know that mineral content does not ‘address the presence of bacteria and viruses.’Dr Hesham Lotfy, a scientist employed at the University of Namibia (UNAM) said that mineral content, whether high or low, should be fine if they are within the guidelines.He explained that ‘most of the known specifications indicate that up to 500 mg/L TDS is acceptable. World Health Organization 1999 specifications indicated that customers should complain at 1000 mg/l.’What is most important to Dr Hesham, and others, is that the concentration of substances such as ‘metal ions, such as Antimony, Arsenic, Copper, Lead , Mercury and Selenium should be indicated.’Dr Hesham said that the most crucial things to look at are the disinfection steps that were taken.’I would want to know what the concentration of the total coliform bacteria in the water is. We need to know that they do bacterial inspections,’ he said.He noted that an additional disinfecting step ‘using UV, ozonation or chlorination is necessary after reverse osmosis to ensure safety.’ SANBWA standards in South Africa require a ‘mandatory sterilisation step after reverse osmosis,’ Metcalf said. UV and ozonation treatments are the most often used treatments to kill and remove bacteria from drinking water.Oldest trickIn the bookTDS content is often used as a basis for a popular scam, the so-called ‘precipitator’ or ‘jam jar’ purity test. This scam is used by bottled water salesmen to falsely convince customers that water with a low TDS is healthier than water with a higher mineral content.The method is simple: The salesman will use a very crude electro-chemical circuit. Water without minerals will not conduct an electric current between two electrodes whereas water containing minerals (TDS) conducts the current and dissolves the one electrode, creating a brown and murky suspension in the water. This gives the consumer the impression that the water is contaminated and not safe to drink.The salesman then compares this to the very low TDS of water from his reverse osmosis unit. In this way, he falsely ‘demonstrates’ that water containing a lower TDS is pure when compared to water with a high TDS content.’This is high school chemistry and misleading marketing – show them the door!’ SANBWA recommends.And now …Diet waterAnother misleading statement put on labels of bottled water, is that the water is ‘weight loss water’’ or is ‘calorie free’.At least two Namibian bottled water companies advertise their water as weight loss or calorie free water.According to Metcalf, ‘bottled water does not contain calories, except for flavoured or enhanced water where sugar and calorie-containing additives have been added’. Metcalf added that, under legislation in South Africa, related to the labelling and advertising of foodstuffs, labelling pure water as calorie free is a ‘negative claim’.’It should say a naturally calorie free product or that bottled water is a naturally calorie free drink,’ she explained.Eish2O water recently advertised a new bottled water label, Eish2O ‘lean’ and the pamphlet claims ‘sometimes we believe that just drinking Eish2O will help weight loss’.The label on Finkenstein Natural Mineral Water also indicates that the water has ‘no calories’, which is misleading as all water is calorie free, except if flavourants are added.

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