Assessment of health-related risks associated with domestic water uses in the Mekong Delta of Vietnam

The Mekong Delta in the South of Vietnam is characterized by its intensive agricultural production. Access to safe and clean water supplies for drinking and domestic services is poor, especially for rural communities. Water-related diseases are prevalent and may lead to loss of income to families, threat economical development in the region and may even lead to increased morbidity. This study aims at defining health-related risks associated with the use of different drinking/domestic water sources and providing advices to authorities in Vietnam on how to reduce incidences of water-related diseases. The quality of 248 surface-, 116 ground-, 78 household harvested rain- and 41 piped-water samples were assessed for salinity, nutrients, metal(loid)s and microbial indicator bacteria. In addition, 40 household-stored surface- and groundwater and 10 bottled water samples were collected for reference data. Water quality maps were developed to identify hot-spot areas of pollution for surface- and groundwater. Furthermore, 532 household interviews were conducted in the Can Tho, Hau Giang and Soc Trang provinces during November 2011 – September 2012 to assess people’s use as well as perception and handling practices towards these water sources. All investigated water sources were contaminated at levels that may pose risks to human health. Surface water in lower order canals, which are intensively used by rural communities for drinking and domestic purposes, is heavily polluted by (untreated) waste water, soil leaching and agrichemicals, leading to elevated concentrations of nutrients, metals and pathogens. In coastal areas, sea water intrusion render the surface water saline and hence unsuited for domestic or agricultural uses. Groundwater is particularly contaminated with nutrients and metals, including manganese and arsenic, and occasionally with pathogens. Due to intense over-exploitation of groundwater sources for drinking water supply and irrigation, many groundwater bodies have become saline and unsuitable for drinking. Groundwater must in future be used sparingly to avoid a further decline in its quality. The rainwater harvested by household contains elevated concentrations of pathogens due to unhygienic handling and storage practices. Also lead (Pb) was detected in harvested rainwater originating most probably from gutter systems. The quality of piped-water varied considerably between investigated stations. Especially in remote rural areas, supply stations often provide water of insufficient quality. Consequently, many households prefer resorting to alternative water sources for drinking and domestic uses, leading to poor maintenance and even the abandonment of supply stations. The quality of bottled water requires more detailed investigations as hundreds of brands of bottled water are currently marketed to communities in the Mekong Delta. While poor water quality is widely recognized, most inhabitants of the Mekong Delta are not truly aware of the risks associated with its use and consumption. In general, people perceive water as clean and safe for use when physical conditions like smell, color, taste and odor are positively judged. As a result, perceived clean water sources are generally not treated via i.e. alum and/or disinfected prior to consumption although it may be severely contaminated and pose a risk to human health. Particularly the household harvested rainwater is generally not treated or disinfected and entails the highest health-related risks from all investigated water sources as it is frequently contaminated with E. coli and other coliform bacteria. Despite being generally treated with alum (Al-chloride), surface- and groundwater contain the highest concentrations of metal(loid)s, potentially causing severe health-related risks. Moreover, the alum treatment does not effectively remove arsenic and contaminated surface- and/or groundwater may be unsafe to drink even when people apply treatment. The development of piped-water supply station is seen, by (inter)national organizations and governments, as the main solution to provide access to safe and clean water. However, the predominant rural populations of the Mekong Delta have limited access to piped-water supply. Therefore, the use of harvested rainwater during the wet season and in some instances of ground- and/or surface water during the dry season may be recommended to rural communities, provided that the users are aware of associated health-risks and are educated in applying appropriate treatment prior to consumption. Such treatments may comprise disinfection of surface and rain water and water filtration by sand and stone filters to reduce metal concentrations in groundwater

Piped-water supplies in rural areas of the Mekong Delta, Vietnam: water quality and household perceptions

In the Mekong Delta (MD) in Vietnam, piped-water supply stations are being intensively built to reach the millennium development goal (MDG) to provide safe and clean drinking water resources to communities. However, studies focusing on the effectiveness of supply stations in reaching these goals are scarce to date. Water samples from 41 water supply stations in the MD were collected between June and October 2012. Water samples were analyzed for general parameters, salinity, nutrients, metal(loid)s and microbial indicator bacteria and compared with World Health Organization (WHO) and Vietnamese drinking water guidelines. In addition, 542 household interviews were conducted to investigate the connection rate to piped-water and people’s perceptions regarding piped-water supplies. The results show that water guidelines were exceeded for pH (min. 6.2), turbidity (max. 10 FTU), Cl (max. 1,576 mg·L−1), NH4 (max. 7.92 mg·L−1), Fe (431.1 µg·L−1), Hg (11.9 µg·L−1), and microbial indicator bacteria (max. total coliform 50,000 CFU 100 mL−1). Moreover, more than half of the interviewed households with access to a piped-water supply did not use this supply as a source of drinking water due to (i) high connection fees; (ii) preference for other water sources; and (iii) perceived poor quality/quantity. Our study shows that the maintenance and distribution of water supply stations should significantly improve in order for piped-water to become a reliable drinking water source. Additionally, alternatives, such as rainwater harvesting and decentralized treatment facilities, should also be considered

Effects of local and spatial conditions on the quality of harvested rainwater in the Mekong Delta, Vietnam

The objective of this study was to assess the quality of harvested rainwater in the Mekong Delta (MD), Vietnam for local (roof types, storage system and duration) and spatial (proximity of industry, main roads, coastline) conditions. 78 harvested rainwater samples were collected in the MD and analyzed for pH, turbidity, TDS, COD, nutrients (NH4, NO3, NO2, o-PO4), trace metals and coliforms. The results show that thatch roofs lead to an increase of pollutants like COD (max 23.2 mgl−1) and turbidity (max 10.1 mgl−1) whereas galvanized roofs lead to an increase of Zn (max 2.2 mgl−1). The other local and spatial parameters had no or only minor influence on the quality of household harvested rainwater. However, lead (Pb) (max. 16.9 μgl−1) and total coliforms (max. 102 500 CFU100 ml−1) were recorded at high concentrations, probably due to a variety of household-specific conditions such as rainwater storage, collection and handling practices

Spatial and temporal variability of surface water pollution in the Mekong Delta, Vietnam

Surface water pollution in the Vietnamese Mekong Delta (MD) could threaten human, animal and ecosystem health given the fact that this water source is intensively used for drinking, irrigation and domestic services. We therefore determined the levels of pollution by organic pollutants, salts, metals and microbial indicators by (bi)monthly monitoring of canals between November 2011 and July 2012 at 32 sampling locations, representing fresh and saline/brackish environments. The results were compared with national water quality guidelines, between the studied regions and with water quality data from main waterways. Key factors explaining the observed levels of pollution in surface water were identified through principal component analysis (PCA). Temporal variations due to tidal regime and seasonality were also assessed. Based on regression models, the spatial variability of five water quality parameters was visualized using GIS based maps. Results indicate that pH (max. 8.6), turbidity (max. 461 FTU), maximum concentrations of ammonium (14.7 mg L− 1), arsenic (44.1 μg L− 1), barium (157.5 μg L− 1), chromium (84.7 μg L− 1), mercury (45.5 μg L− 1), manganese (1659.7 μg L− 1), aluminum (14.5 mg L− 1), iron (17.0 mg L− 1) and the number of Escherichia coli (87,000 CFU 100 mL− 1) and total coliforms (2,500,000 CFU 100 mL− 1) in canals exceed the thresholds set by Vietnamese quality guidelines for drinking and domestic purposes. The PCA showed that i) urbanization; ii) metal leaching from soils; iii) aquaculture; and iv) tidal regime explain 85% of the variance of surface water quality attributes. Significant differences in water quality were found due to daily tidal regime and as a result of seasonality. Surface water quality maps for dissolved oxygen, ammonium, ortho-phosphate, manganese and total coliforms were developed to highlight hot-spot areas of pollution. The results of this study can assist policy makers in developing water management strategies and drinking water companies in selecting optimum water extraction locations

Investing in Urban Blue–Green Infrastructure—Assessing the Costs and Benefits of Stormwater Management in a Peri-Urban Catchment in Oslo, Norway

Cities are challenged by climate change impacts, such as extreme rainfall events that affect conventional urban water management systems via increased sewage water overflows resulting in water quality deterioration and urban floods causing infrastructure damage. Investments in blue–green infrastructure (BGI) are increasingly considered to address these issues. However, these should be cost-effective. In this study, the effectiveness of five different BGI strategies and one grey strategy are assessed for a peri-urban catchment area in Oslo (Grefsen) using a cost–benefit analysis. The strategies include (i) wadis; (ii) green roofs; (iii) raingardens, rain barrels and wadis; (iv) infiltration crates; (v) water squares, and (vi) a separate sewage system. Besides economic effectiveness, the study also aims to identify the proper protection level by comparing cost–benefit ratios and net benefits for 60-min rainfall events occurring once every 5, 20, and 100 years (M5, M20, and M100), concerning both the current situation and under future climate change (using the Representative Concentration Pathway 8.5). The analyses revealed the highest BC ratios for wadis (12.0–17.3), separate sewage systems (7.7–15.1), and a combination of raingardens, rain barrels, and wadis (1.6–2.3). Strategies dimensioned for less frequent but more intensive rainfall events yielded higher BC ratios. Results for infiltration crates were difficult to interpret and were found to be very sensitive to input parameters. The other strategies implied a negative BC ratio. The study concludes that investments in BGI in Grefsen, Oslo, can be positively judged from a social–economic perspective and provide suitable information for water-related decision makers to decide upon the strategy selection and the appropriate flood protection level.publishedVersio

Piped-Water Supplies in Rural Areas of the Mekong Delta, Vietnam: Water Quality and Household Perceptions

In the Mekong Delta (MD) in Vietnam, piped-water supply stations are being intensively built to reach the millennium development goal (MDG) to provide safe and clean drinking water resources to communities. However, studies focusing on the effectiveness of supply stations in reaching these goals are scarce to date. Water samples from 41 water supply stations in the MD were collected between June and October 2012. Water samples were analyzed for general parameters, salinity, nutrients, metal(loid)s and microbial indicator bacteria and compared with World Health Organization (WHO) and Vietnamese drinking water guidelines. In addition, 542 household interviews were conducted to investigate the connection rate to piped-water and people’s perceptions regarding piped-water supplies. The results show that water guidelines were exceeded for pH (min. 6.2), turbidity (max. 10 FTU), Cl (max. 1,576 mg·L−1), NH4 (max. 7.92 mg·L−1), Fe (431.1 µg·L−1), Hg (11.9 µg·L−1), and microbial indicator bacteria (max. total coliform 50,000 CFU 100 mL−1). Moreover, more than half of the interviewed households with access to a piped-water supply did not use this supply as a source of drinking water due to (i) high connection fees; (ii) preference for other water sources; and (iii) perceived poor quality/quantity. Our study shows that the maintenance and distribution of water supply stations should significantly improve in order for piped-water to become a reliable drinking water source. Additionally, alternatives, such as rainwater harvesting and decentralized treatment facilities, should also be considered