Bacteriological assessment of drinking water supply options in coastal areas of Bangladesh

Abstract

This study was conducted to assess the bacteriological quality of alternative drinking water supply options in southwest coastal areas of Bangladesh. A total of 90 water samples were collected during both dry and wet seasons from household based rainwater harvesting systems (RWHSs), community based rain water harvesting systems (CRWHSs), pond-sand filters (PSFs) and ponds. The samples were evaluated for faecal coliform, Escherichia coli and Heterotrophic Plate Count, as well as Vibrio cholerae, Salmonella spp., Shigella spp. and Pseudomonas spp. Physico-chemical parameters (pH, electrical conductivity, and color) were also examined. In addition, sanitary inspections were conducted to identify faecal contamination sources. All options showed varying degrees of indicator bacterial contamination. The median E. coli concentrations measured for RWHSs, CRWHSs, PSFs, and ponds were 16, 7, 11, and 488 cfu/100 ml during the wet season, respectively. Vibrio cholerae O1/O139, Salmonella and Shigella spp. were not found in any samples. However, Vibrio cholerae Non-O1/Non-O139 and Pseudomonas spp. were isolated from 74.4% and 91.1% of the water samples collected during the wet season. A maximum pH of 10.4 was found in CRWHSs. Estimation of the disease burden for all options in disability adjusted life years (DALYs) showed an increased disease burden during the wet season. According to sanitary inspections, poor maintenance and unprotected ponds were responsible for rainwater and PSF water contamination, respectively.The findings of the present study suggest that alternative drinking water supply options available in southwest coastal Bangladesh pose a substantial risk to public health.

Microbiological effectiveness of mineral pot filters as household water treatment in the coastal areas of Bangladesh

“…Rain-feed pond waters are highly polluted due to unhygienic sanitation in and around the pond, indiscriminant usage and lack of protection of the ponds. The FC and E.coli counts were found to vary from 12 to 10,000 and zero to 3000 per 100 mL (Islam et al 2011), respectively, together with the presence of several pathogenic bacteria. Several studies (Islam et al 2011;Karim 2010;Howard et al 2006;Ahmed et al 2005) in Bangladesh showed that the rooftop harvested rainwater was also microbiologically contaminated to a great extent, which may cause significant health risks of the rural people.…”

“…The FC and E.coli counts were found to vary from 12 to 10,000 and zero to 3000 per 100 mL (Islam et al 2011), respectively, together with the presence of several pathogenic bacteria. Several studies (Islam et al 2011;Karim 2010;Howard et al 2006;Ahmed et al 2005) in Bangladesh showed that the rooftop harvested rainwater was also microbiologically contaminated to a great extent, which may cause significant health risks of the rural people. Studies from other countries (Despins et al 2009;Sazakil et al 2007;Meera and Ahammed 2006) also reported microbial contamination of harvested rainwater and consumption of the water may cause a variety of infectious diseases around the world (Lye 2002).…”

“…This study was conducted in Dacope and Mongla areas of Khulna and Bagerhat districts, which is the same study area as reported by Islam et al (2011), located in the southwest coastal areas of Bangladesh. People in these areas mainly depend on PSF, RWH and rainfeed pond water for drinking water supply.…”

“…Several recent studies (Islam et al 2011;Karim 2010;Ahmed et al 2005) showed that water from rain-feed ponds, PSFs and RWHs is microbiologically unsafe. The fecal coliforms (FC) counts in PSF water were found to vary from zero to over 4000 per 100 mL (Islam et al 2011;Kamruzzaman and Ahmed 2006) and FC was found in about 97% samples (Ahmed et al 2005). Rain-feed pond waters are highly polluted due to unhygienic sanitation in and around the pond, indiscriminant usage and lack of protection of the ponds.…”

“…and Salmonella spp. were confirmed by a battery of biochemical tests (Islam et al, 2011). For isolation of Pseudomonas spp., two loopfuls of enrichment broth were taken and inoculated onto Cetrimide agar, which were then incubated overnight at 37 O C. After overnight incubation, green-yellow to blue-green colonies were identified as Pseudomonas spp.…”