THE Pasteur Institute, a Government laboratory has confirmed that the pH level of the PHE Water from a certain area of Upper Shillong is 5.7 which is slightly acidic. The word slightly might gives a sense of relief to the consumers but let us hear what the experts say. In general, water with a pH < 7 (less than 7) is considered acidic and with a pH > 7 is considered basic. The normal range for pH in surface water systems is 6.5 to 8.5 and for groundwater systems 6 to 8.5. Alkalinity is a measure of the capacity of the water to resists a change in pH that would tend to make the water more acidic. The measurement of alkalinity and pH is needed to determine the corrosiveness of the water.
The pH of pure water (H20) is 7 at 25o C, but when exposed to carbon dioxide in the atmosphere this equilibrium results in a pH of approximately 5.2. Because of the association of pH with atmospheric gases and temperature, scientists believe that it is such water be tested as soon as possible. While the pH of the water is not indicative of the strength of the acidic or basic solution and this alone does not provide a full picture of the characteristics or limitations with the water supply but is is a cause for concern and requires a more intensive study to determine whether the water is potable. In general, water with a low pH (< 6.5) could be acidic, soft, and corrosive. Therefore, the water could leach metal ions such as iron, manganese, copper, lead, and zinc from the aquifer, plumbing fixtures, and piping. Therefore, water with a low pH could contain elevated levels of toxic metals, cause premature damage to metal piping, and have associated aesthetic problems such as a metallic or sour taste, staining of laundry, and the characteristic blue-green staining of sinks and drains. We can well imagine what effect such water would have on the human system. It is pathetic that the PHE has come up with a clarification defending the indefensible. That the Greater Shillong Water Supply System has been a hub of correction is well established. That it has been allowed to continue for decades reveals the rot in the system. Will the public wake up and shake up the entire PHE machinery?