The WHO/UNICEF Joint Monitoring Programme for Water-supply and Sanitation (JMP), which monitors progress on the MDG water supply target, identifies three categories of drinking water supply: (a) water piped into the dwelling, plot, or yard; (b) other improved sources (including public taps, protected springs, hand pumps, and rainwater harvesting); and (c) unimproved sources (open water, unprotected from contamination) . [...]it is clear that many uncertainties remain about how to improve public health through improvements in the water supply. [...]more and better research is desperately needed, in particular larger and longer double-blinded randomized controlled studies of the health impacts of water supply and quality interventions at the community and household level.
Ensuring reliable access to dean and affordable water is one of the greatest global challenges of this century. As the world's population increases, water pollution becomes more complex and difficult to remove, and global climate change threatens to exacerbate water scarcity in many areas, the magnitude of this challenge is rapidly increasing. Wastewater reuse is becoming a common necessity, even as a source of potable water, but our separate wastewater collection and water supply systems are not designed to accommodate this pressing need. Furthermore, the aging centralized water and wastewater infrastructure in the developed world faces growing demands to produce higher quality water using less energy and with lower treatment costs. In addition, it is impractical to establish such massive systems in developing regions that currently lack water and wastewater infrastructure. These challenges underscore the need for technological innovation to transform the way we treat, distribute, use, and reuse water toward a distributed, differential water treatment and reuse paradigm (i.e., treat water and wastewater locally only to the required level dictated by the intended use). Nanotechnology offers opportunities to develop next-generation water supply systems. This Account reviews promising nanotechnology-enabled water treatment processes and provides a broad view on how they could transform our water supply and wastewater treatment systems. The extraordinary properties of nanomaterials, such as high surface area, photosensitivity, catalytic and antimicrobial activity, electrochemical, optical, and magnetic properties, and tunable pore size and surface chemistry, provide useful features for many applications. These applications include sensors for water quality monitoring, specialty adsorbents, solar disinfection/decontamination, and high performance membranes. More importantly, the modular, multifunctional and high-efficiency processes enabled by nanotechnology provide a promising route both to retrofit aging infrastructure and to develop high performance, low maintenance decentralized treatment systems including point-of-use devices. Broad implementation of nanotechnology in water treatment will require overcoming the relatively high costs of nanomaterials by enabling their reuse and mitigating risks to public and environmental health by minimizing potential exposure to nanoparticles and promoting their safer design. The development of nanotechnology must go hand in hand with environmental health and safety research to alleviate unintended consequences and contribute toward sustainable water management.
Competing interests: I have read the journal's policy and have the following conflicts: TS is a Senior Statistics and Monitoring Specialist at UNICEF and manages the WHO/UNICEF Joint Monitoring Programme for Water Supply and Sanitation; CB consults for UNICEF, the World Bank, and WHO; CB is on an advisory committee for a CLTS project undertaken by PLAN International USA and is paid for this work; CB is a member of the Board of Trustees of WaterAid; CB is Chair of the Advisory Committee of One Drop Foundation; CB is a member of the Strategic Advisory Group of the WHO-UNICEF Joint Monitoring Program and the UN Water GLAAS Report; CB is a past board member of WaterCan (now WaterAid Canada). Piped supplies on premises not only reduce the time and effort required to collect water, and thereby increase the amount of water available for personal and domestic needs but also are more likely to provide water that meets required standards for drinking water quality.
The largest environmental challenge that Jordan faces today is the scarcity of water. Current water use already exceeds renewable supply. Many methods have been suggested to increase the sources of water supply; one alternative source is rainwater harvesting. Rainfall harvesting from rural/urban catchments has not received large attention in Jordan. In the absence of run-off sewer systems in most Jordanian rural and urban areas, rainfall harvesting from roads, parking lots and rooftops can increase water supply for various domestic uses and help combat the chronic water shortages in the country. The objectives of this paper are to (1) evaluate the potential for potable water savings by using rainwater in residential sectors of the 12 Jordanian governorates; and (2) provide some suggestions and recommendations regarding the improvement of both quality and quantity of harvested rainwater. Results show that a maximum of 15.5 Mm /y of rainwater can be collected from roofs of residential buildings provided that all surfaces are used and all rain falling on the surfaces is collected. This is equivalent to 5.6% of the total domestic water supply of the year 2005. The potential for water harvesting varies among the governorates, ranging from 0.023×10 m for the Aqaba governorate to 6.45×10 m for the Amman governorate. The potential for potable water savings was estimated for the 12 governorates, and it ranged from 0.27% to 19.7%. Analysis of samples of harvested rainwater from residential roofs indicated that the measured inorganic compounds generally matched the WHO standards for drinking water. On the other hand, fecal coliform, which is an important bacteriological parameter, exceeded the limits for drinking water.
A monitoring study of 31 pharmaceuticals along Lisbon's drinking water supply system was implemented, which comprised the analysis of 250 samples including raw water (surface water and groundwater), and drinking water. Of the 31 pharmaceutical compounds, only sixteen were quantified in the analyzed samples, with levels ranging from 0.005 to 46 ng/L in raw water samples and 0.09–46 ng/L in drinking water samples. The human health risk assessment performed showed that appreciable risks to the consumer's health arising from exposure to trace levels of pharmaceuticals in drinking water are extremely unlikely, as RQs values were all below 0.001. Also, pharmaceuticals were selected as indicators to be used as a tool to control the quality of raw water and the treatment efficiency in the drinking water treatment plants.
Wildland fire impacts on surface freshwater resources have not previously been measured, nor factored into regional water management strategies. But, large wildland fires are increasing and raise concerns about fire impacts on potable water. Here we synthesize long-term records of wildland fire, climate, and river flow for 168 locations across the United States. We show that annual river flow changed in 32 locations, where more than 19% of the basin area was burned. Wildland fires enhanced annual river flow in the western regions with a warm temperate or humid continental climate. Wildland fires increased annual river flow most in the semi-arid Lower Colorado region, in spite of frequent droughts in this region. In contrast, prescribed burns in the subtropical Southeast did not significantly alter river flow. These extremely variable outcomes offer new insights into the potential role of wildfire and prescribed fire in regional water resource management, under a changing climate.
In many parts of the world, forests provide high quality water for domestic, agricultural, industrial, and ecological needs, with water supplies in those regions inextricably linked to forest health. Wildfires have the potential to have devastating effects on aquatic ecosystems and community drinking water supply through impacts on water quantity and quality. In recent decades, a combination of fuel load accumulation, climate change, extensive droughts, and increased human presence in forests have resulted in increases in area burned and wildfire severity-a trend predicted to continue. Thus, the implications of wildfire for many downstream water uses are increasingly concerning, particularly the provision of safe drinking water, which may require additional treatment infrastructure and increased operations and maintenance costs in communities downstream of impacted landscapes. A better understanding of the effects of wildfire on water is needed to develop effective adaptation and mitigation strategies to protect globally critical water supplies originating in forested environments.
Supplying piped water intermittently is a common practice throughout the world that increases the risk of microbial contamination through multiple mechanisms. Converting an intermittent supply to a continuous supply has the potential to improve the quality of water delivered to consumers. To understand the effects of this upgrade on water quality, we tested samples from reservoirs, consumer taps, and drinking water provided by households (e.g. from storage containers) from an intermittent and continuous supply in Hubli–Dharwad, India, over one year. Water samples were tested for total coliform, , turbidity, free chlorine, and combined chlorine. While water quality was similar at service reservoirs supplying the continuous and intermittent sections of the network, indicator bacteria were detected more frequently and at higher concentrations in samples from taps supplied intermittently compared to those supplied continuously ( < 0.01). Detection of was rare in continuous supply, with 0.7% of tap samples positive compared to 31.7% of intermittent water supply tap samples positive for . In samples from both continuously and intermittently supplied taps, higher concentrations of total coliform were measured after rainfall events. While source water quality declined slightly during the rainy season, only tap water from intermittent supply had significantly more indicator bacteria throughout the rainy season compared to the dry season. Drinking water samples provided by households in both continuous and intermittent supplies had higher concentrations of indicator bacteria than samples collected directly from taps. Most households with continuous supply continued to store water for drinking, resulting in re-contamination, which may reduce the benefits to water quality of converting to continuous supply.