It means the presence of pathogens from faeces of humans and animals is highly likely in this water drunk by residents.
A group of researchers at Bangladesh Agricultural Research Council or BARC mined the ‘horrifying’ data while studying the level of minerals in jars, and bottled water in the city, BARC Director Monirul Islam told bdnews24.com.
The researchers sampled 250 jars from across the city’s Farmgate, Karwan Bazar, Elephant Road, New Market, Chawk Bazar, Sadarghat, Keraniganj, Jatrabarhi, Motijheel, Basabo, Malibagh, Rampura, Mohakhali, Gulshan, Banani, Uttara, Airport, Dhanmondi, Mohammadpur, Mirpur, Gabtoli, and on the city’s outskirts at Aminbazar, Savar and Ashulia.
The level of coliform bacteria in the samples collected from Elephant Road, Chawk Bazar, Basabo, Gulshan and Banani areas was found significantly high in the research.
Coliform bacteria are organisms that are present in the environment and the faeces of all warm-blooded animals and humans.
These bacteria will not likely cause illness. However, their presence in drinking water indicates that disease-causing organisms or pathogens could be in the water system, according to the US Department of Health.
The study found the highest level of total coliform in jar water of Sadarghat in Chawk Bazar.
The level of total coliform in these samples was 1,600mpn (most probable number) per 100 millilitres.
The level of faecal coliform in these samples was 240mpn/100ml.
The lowest levels of total coliform and faecal coliform in Dhaka jar water were found to be 17mpn/100ml and 11mpn/100ml respectively.
The total coliform group is a large collection of different kinds of bacteria. Faecal coliforms are types of total coliform that mostly exist in faeces.
“We’ve found both in 97 percent jars. This is a risk for public health,” he said.
Monirul said coliforms act as catalysts for the creation of pathogens that cause long-term diarrhoea, headache, nausea, stomach ache, fever and cold besides decreasing disease prevention power.
He said humans below five years old and above 60 could suffer from the haemolytic uremic syndrome, which affects the blood and blood vessels, destroying blood platelets, a low red blood cell count or anaemia and kidney failure.
It would take two to three days, or at least a week in many cases, to detect the syndrome, Monirul said.
According to the researchers, Bangladesh Standards and Testing Institution or BSTI has set the standard of water commercially supplied for drinking, but the business of contaminated water is continuing due to lack of regulation.
Monirul said faecal coliforms mix with water through leaks in lines of Dhaka Water Supply and Sewerage Authority or WASA.
“And this water is sold in jars without or after partial filtering. So the germs remain in the water,” he said.
According to him, the only way to free WASA water from germ is to boil it.
Bottled water too
The researchers have found that the bottled water companies are also not following the BSTI standards.
The study says almost all the bottles have anomalies in the levels of components provided on the labels.
The amount of total dissolved solids or TDS in the bottled water which affects the taste was found to be between 8 milligrams and 280mg per litre while up to 500mg is allowed.
But coliforms were found in the bottles also. The level was less than 1.8mpn/100ml.
Monirul said the authorities should monitor the bottled water firms so that they cannot put imaginary numbers on the labels.