KARACHI, May 11: Sterilisation of drinking water through sunlight has been recommended in a research conducted by two associate professors of Dow University of Health Sciences. The method is one of the five promising techniques recommended by the World Health Organisation for disinfecting water.

The research was presented by Dr M. Rafiq Khanani of Dow International Medical College and Dr Khurshid Hashmi of Sindh Medical College at a press conference at Dow University of Health Sciences on Friday. The research was conducted by the DUHS and Infection Control Society of Pakistan.

Giving details of the research, Prof Khanani said water samples from taps and wells were collected in clean plastic bottles. Three bottles, two of them contained microbes, were exposed to sunlight for two to eight hours, while one was kept in shade. Later, bottles were checked for bacterial growth and it was revealed that solar disinfectant technique was highly effective in killing all diseases causing bacteria, he said.

“There was no growth of any bacteria in bottles exposed to sunlight for over three hours in both contaminated and non-contaminated samples. Though the WHO’s recommended minimum limit is six hours, we found positive results in three hours. This method kills all viruses and parasites,” he said.

He said discarded mineral water bottles (preferably PET) or transparent beverage bottles of one or two litres capacity should be used for the purpose. “The bottles should be closed tightly and any label or glue should be removed before putting them in sunlight for over three hours. The water can be stored in these bottles for a week,” he said.

He said large bottles having more than three-litre capacity could not be used for the purpose as ultraviolet rays could not penetrate into more than four inches thickness of water column. About the filters, he said the filters recommended by the WHO for decontamination were ceramic filters and not the fiber ones which were being widely used in Pakistan.

This method was first developed by Swiss Federal Institute for Environmental Science and Technology and one of the most practical and economical methods, he said.

About the number of deaths caused by diarrhoeal diseases (gastroenteritis) in Pakistan, he said: “It kills 250,000 to 300,000 people every year. It is the highest cause of morbidity and the third highest cause of mortality. Among children under five years it accounts for 28 per cent of all deaths.

Other infections caused by filthy water included typhoid, Hepatitis A and E,” he said.

Earlier, Dow University of Health Sciences Vice Chancellor Masood Hameed Khan said though the research was still in progress and would complete in February 2008, it was deemed necessary to share its findings in view of the increasing number of gastroenteritis cases being reported these days.

The university would send the research document to the provincial and federal governments and suggest them to include this method in initiatives to make safe drinking water accessible to common man, he said.