This is according to utility Rand Water, which tested the shelf-life of five brands of locally bottled water in a year-long study.
Researchers Yvonne Liee and Karl Lubout found all bottled water brands had a very limited shelf-life. Keeping them longer than a few days or weeks was likely to produce water with an unpleasant taste and smell and "high bacteriological counts that can affect the immuno-compromised".
This included chemotherapy patients, people living with Aids, organ-transplant recipients, the chronically ill, elderly patients or very young children whose immune systems were not fully developed.
The study noted that all the brands exceeded the bacterial "alert level" guidelines of 5 000 colony-forming units/millilitre.
On the positive side, none of the bottled water samples showed traces of faecal pollution such as E.coli, and all samples complied with SA National Standards guidelines for inorganic pollutants such as mercury, aluminium, chromium, arsenic and manganese.
The study was conducted to determine the shelf-life of locally bottled water as Rand Water was exploring the feasibility of getting into the bottled water market, the report read. - (Sapa)