Ensuring quality of drinking water

Bangladesh is on the verge of setting the Sustainable Development Goals (SDGs) based on the bigger challenges the country has been facing. As SDGs are going to replace the Millennium Development Goals (MDGs) over the next 15 years (2016-30), smarter and more effective solutions are needed to meeting the challenges. According to Dr. Bjorn Lomborg (president of the Copenhagen Consensus Centre, a top-ranking think tank), the smarter solutions to address each of the challenges will be identified keeping in focus cost and benefit analyses. A countrywide discussion was recently held involving the relevant stakeholders on various themes that included education, poverty, health systems, non-communicable diseases, digital Bangladesh, climate change, environment and biodiversity, water and sanitation, gender equality, urbanisation, etc. Ensuring quality of drinking water has been greatly stressed by many professionals as one of the biggest challenges for the country and investment in it can be considered a key component of development. Availability of and access to safe drinking water not only ensure health benefits but also bring social, environmental and economic dividends.

Access to safe drinking water is an emerging global problem amid changing climatic conditions, increasing populations and urbanisation. Contaminants released into the environment threaten water safety and children living in this polluted environment are susceptible to harmful objects in water. Water quality needs to be assessed on the basis of acceptable limits of water parameters; otherwise human health is at risk if the values exceed acceptable limits.

As part of a cross-section social survey across the country, the writers of the article have visited households to check the permissible safe drinking water limits set by the WHO and Bangladesh government. They have found the drinking water to be slightly alkaline but within acceptable limits. A controlled pH of water is suggested in the WHO guideline to reduce the corrosion and contamination of drinking water having health consequences. Manganese concentrations have been found to be varying from 0.1 mg/L to 5.5 mg/L (mean 0.3 mg/L). The mean value of manganese concentrations has exceeded the Bangladesh standards in water at most of the study sites. Children are found to be particularly vulnerable to higher manganese concentrations due to their low protective mechanisms. Approximately, eight per cent of children under study were exposed to excessive manganese concentrations that exceeded both the WHO and Bangladesh standards (>0.4 and >0.1 mg/L, respectively). Several studies have reported that exposure to high manganese concentrations poses threat to children's cognitive, behavioural, and neuropsychological health.

The mean iron concentrations in water exceeded WHO standards (0.3 mg/L) at all sample sites, but remained within Bangladeshi standards (1.0 mg/L) at a few sample sites. Approximately two per cent of women in the developed countries and 50 per cent in the developing countries are anaemic, meaning higher rates of maternal mortality are found in developing countries. More recent studies have reported iron deficiency as being the most important determinant of seven per cent to 60 per cent of anaemia cases in Bangladesh.  In the study mentioned, about half of the female participants were found to be exposed to higher iron concentrations in drinking water which exceeded both WHO and Bangladesh standards. There is a contradiction related to iron concentrations: on the one hand, iron deficiency can cause anaemia and fatigue, while on the other, excess iron can cause multiple organ dysfunction (e.g., liver fibrosis and diabetes).

The joint study has found higher salinity concentrations in water in the coastal districts. Salinity problems in the country's coastal regions are thought to be the effects of sea level rise, and industrial and domestic wastes. According to a group of researchers, approximately 20 million people living in coastal Bangladesh are dependent on tube-wells, rivers, and ponds for drinking water and these sources are increasingly becoming saline due to the rising sea level. Salinity has intruded into over 100 km inland from the Bay of Bengal.  In a 2008 survey, higher rates of pre-eclampsia and hypertension were reported in the coastal areas compared to non-coastal regions.

Most of the households in Dohar, Shibchar, and Sonargaon use shallow tube-wells for drinking water, which have been affected by high levels of arsenic. In Shibchar (West Kakor village), most of the tube-wells are affected by arsenic contamination and the villagers have been found to be unable to detect the arsenic-free tube-wells. Therefore, they collect drinking water from whichever tube-well they find nearby.  In some cases (e.g., Sonargaon), people collect drinking water from arsenic-affected sources, even though they know that the water is contaminated and is damaging to health. Most respondents at the sample sites use shallow tube-wells to obtain drinking water due to lower installation costs of the pumps. In the coastal districts such as Barguna, Satkhira, and Khulna, water from both shallow and deep tube-wells are salty, as reported by the respondents.

To assess the suitability of drinking water in terms of combined effects of chemical parameters (pH, iron, manganese, salinity and arsenic) on drinking water, the writers have used water quality index (WQI) method. Higher values of iron, manganese and arsenic have reduced the drinking water quality. Unplanned waste disposal, agricultural run-off including pesticides, fertilisers, and other environmentally hazardous activities are thought to contribute to water pollution. Hygienic management of drinking water sources and monitoring of human activities surrounding water sources are imperative to improve water quality. Increased awareness of water pollution and hygienic management of drinking water at each point from source to consumption can ensure people's health and reduce risks.

The writers are researchers at Research and Evaluation Division, BRAC.

tahera.a@brac.net