Present status and trends in the eater supply and sanitation in Bangladesh

Abstract

In Bangladesh, the water supply and sanitation sector has achieved commendable success over the last few decades. Overall about ninety eight percent of the rural population and almost the entire urban population now have access to water from tubewell, tap or ring-well. Currently, the entire rural water supply program is being threatened due to widespread detection of arsenic in the tubewell water from shallow aquifer. Reliable delineation of arsenic affected areas and estimation of arsenic-affected population is very important in the overall management of the arsenic crisis. In this study, estimation of arsenic affected population was made for the year 2000 based on available data on population distribution and arsenic concentration in tubewell water. Over 30 million people of Bangladesh, which is about 24 percent of population (about 130 million), has been estimated to be exposed to arsenic concentration above the drinking water standard of 50 ppb. Majority (over 27 millions) of arscnic affected population lives in the rural areas. About 27 percent of rural population and about 12 percent of urban population have been estimated to be exposed to arsenic concentration abovc 50 ppb. Alternative water supply options for arsenic affected areas of Bangladesh have been evaluated in this study based on available information. Broadly, supply of arsenic-free safe water can be accomplished: (i) by avoiding arsenic contaminated water by using alternate groundwater source or surface water source, and (ii) by treating the arsenic contaminated groundwater. Groundwater development options include VSST, shallow tubewell at greater depth, arsenic-free deep tubewell and dug well. Surface water development options include Pond Sand Filter (PSF), infiltration gallery and household filters. Rainwater harvesting is another possible option. All these techniques have certain advantages and disadvantages and they are not equally applicable in all areas of Bangladesh. Arsenic contaminated groundwater can be treated by a number of processes such as oxidation, co-precipitation, sorptive filtration, ion exchange and membrane techniques. Different types of household and community-based arsenic removal have been tested in the field and some are still being tested. Results from available data suggest that many of the arsenic removal units, mostly based on coagulation and sorptive filtration, have performed well in the field. These units can potentially play an important role, at least in the short-term, as an effective means of providing safe drinking water to arsenic-affected population. In addition to arsenic, other problems that impede the progress in safe water access include saline water intrusion in the coastal areas, high iron content, lowering of groundwater table during the dry season and problems in rocky and hilly areas. The upper aquifers of the lowlying coastal areas are mostly saline and potable waters are usually available only at great depths. Deep tubewells yielding fresh water can be constructed throughout most of the coastal belt. However, deep tubewells are much more expensive to construct and, as a result, water supply coverage in the coastal area is lower compared to the rest of the country. Use of river/pond/other sources in the coastal districts, particularly in the western districts, is significantly higher compared to the rest of country. A number of non-conventional water supply technologies, such as SST, VSST, and PSF, are used in coastal areas. The coastal districts also account for the majority (about 90%) of the DTWs operating in the country, while VSST/SST and PSF arc almost exclusively used in the coastal districts. In recent years, deep tubewells and pond sand filters are also getting popularity in the arsenic-affected areas of the country. IV A total of 1230 unions in Bangladesh have been found to have iron content exceeding 5 mg/1. Hand tubewell water in 65 percent of the areas of Bangladesh have been found to have dissolved iron in excess of 2 mg/l and in many areas, the concentration of dissolved iron is around 15 mg/1. However, since iron does not have any major health effects, the people do not consider it a serious problem. Low water table areas (LTW A) and seasonally low water table areas (SLWTA) are having a significant effect on water supply coverage and water supply technology. If the current trend of the lowcring of groundwater table continues, millions of suction hand pumps would required to be replaced by direct action Tara hand pumps. These pumps are already playing a vital role in providing safe drinking water supply in low water table areas and by the year 2010, Tara pumps are predicted to be responsible for water supply in about 50% of the Upazillas in Bangladesh. An evaluation of rural and urban sanitation situation has also been made in this study. Progress in the sanitation sector is much slower compared to the water supply sector. Use of sanitary latrine has increased from 1% to 16% in 1990 to about 40% in 1997. The trend seems to have leveled off since 1993 and use of sanitary latrine remained between 30 to 40 percent. More than two-third of the rural population still use unsanitary (hanging) latrines or practice open defecation. Less than half the urban population use water seal latrine and only two-third of the population use pit and/or water-seal latrines. Unhygienic hanging latrine and open defecation are still being practiced in the urban areas. Social mobilization and hygiene education plays a ccntral in the success of any sanitation program. Role of women is also vital for success in the sanitation program.