Acidic well water


In the most recent episode where well water in the Weliveriya area got acidic brings about several pertinent questions as to the safety of the water people drink from their wells. It is important to understand the complexities of how well water can get affected from a factory which is relatively far from the inhabitants. Water in the affected area underlain with lateritic rocks is generally more acidic than the well water from other areas of the country. Also the buffering action which refers to the ability of such rocks to neutralise excessive acidity is very poor. Laterite is relatively widespread in the western province particularly in the Gampaha district. In a previous episode, a sulphuric acid plant installed at Ranala had to be closed down owing to complaints of villagers that their well waters have become acidic as a result of leakage of acid from this factory. Unlike granite, this rock is more porous, water can easily seep through the rock and make well water acidic.

One important point to ask is what the Central Environmental authority (CEA) has to say about this recent phenomenon. They have the mandate to check that industries function according to stipulated environmental standards. For example, industrial waste waters should be neutralised to a pH of 6.0 before discharging into the inland waterways. If the waste water is basic it should be reduced to a pH of 8.5. Thus, the water coming from any industrial operation should be treated on site in a wastewater treatment plant so that the pH of the water discharged is in the range of 6.0 – 8.5. For those who are not familiar with my use of the technical term pH, it suffices to say that lower the pH higher is the acidity and pH of pure water is 7.0 at room temperature. I am not sure whether the factory in question has followed all these safeguards and it is the bounden duty of the CEA to tell the public whether all environmental regulations have been followed by the factory. If they have followed these guidelines, then it is important to scientifically study what the problem is. Water Board too has a moral obligation to check the acidity of the well waters so as to ensure their safety. This involves a simple pH determination and with a portable pH meter this can be easily done.

SLS standard for drinking water (SLS 614 of 1983) is that the desirable pH level is 7.0 - 8.5.. If the pH goes below this, water is too acidic and is not safe to drink. One short term practical solution that I can suggest is to place a layer of dolomitic rocks (not the powder) at the bottom of the well to neutralise the excess acidity. Of course this may leave some hardness in drinking water which is not harmful and also part of this hardness can be removed by boiling the water and filtering the water with a piece of cloth. This is not a permanent solution but it is better than drinking acidic water. I do hope that the Government takes a serious view on these matters and take some meaningful steps to tackle the problem. The recent closure of the factory by gung-ho politicians is not the solution to this problem which will result in the loss of jobs for a large number of people at the factory.

Prof. O. A. Illeperuma

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