Delivery Of Safe Drinking Water Research Articles

Virus contamination from operation and maintenance events in small drinking water distribution systems

We tested the association of common events in drinking water distribution systems with contamination of household tap water with human enteric viruses. Viruses were enumerated by qPCR in the tap water of 14 municipal systems that use non-disinfected groundwater. Ultraviolet disinfection was installed at all active wellheads to reduce virus contributions from groundwater to the distribution systems. As no residual disinfectant was added to the water, any increase in virus levels measured downstream at household taps would be indicative of distribution system intrusions. Utility operators reported events through written questionnaires. Virus outcome measures were related to distribution system events using binomial and gamma regression. Virus concentrations were elevated in the wells, reduced or eliminated by ultraviolet disinfection, and elevated again in distribution systems, showing that viruses were, indeed, directly entering the systems. Pipe installation was significantly associated with higher virus levels, whereas hydrant flushing was significantly associated with lower virus levels. Weak positive associations were observed for water tower maintenance, valve exercising, and cutting open a water main. Coliform bacteria detections from routine monitoring were not associated with viruses. Understanding when distribution systems are most vulnerable to virus contamination, and taking precautionary measures, will ensure delivery of safe drinking water.

DETERMINANTS OF ENVIRONMENTAL NONCOMPLIANCE BY PUBLIC WATER SYSTEMS

Whereas a large number of empirical studies have been devoted to analyzing determinants of environmental compliance (EC) by firms, less attention has been paid to EC by public water systems (PWS). To address this gap in the literature, this article uses data on compliance with maximum contaminant levels (MCL) under the Safe Drinking Water Act for 971 PWS in Arizona and identifies the characteristics of PWS that are associated with violation of MCL standards. Three main findings emerge from the analysis. First, larger PWS are more likely to violate MCL standards than smaller PWS. Second, publicly owned PWS have slightly higher probability of violating MCL standards than privately owned systems. Finally, PWS serving residential areas are more likely to violate MCL standards, as opposed to PWS serving school districts or office buildings. The results suggest that for ensuring safe water for people, effectiveness of monitoring policy, and an efficient utilization of resources, the environmental agencies may focus their monitoring and enforcement efforts on these water systems.(JEL K32, Q53)

The impact of biofilms on water quality in long pipelines

Limited water availability and increased water demand necessitates the use of long pipelines to distribute potable and non-potable water for human consumption or other purposes. The effects of microbial growth and activity on the quality of distributed water have been studied for many years, although in recent years much of this focus has shifted to understanding the effects of biofilms, rather than planktonic microorganisms, on water quality. Recently, it was estimated that 95% of all biomass in water distribution systems is in the form of pipewall biofilms, with only 5% of all biomass in the bulk water phase. Under favourable conditions, biofilms can impact water quality by increasing disinfectant demand, creating taste and odour problems, harbouring opportunistic pathogens and contributing to the potential for discoloured water events. More research is required to inform the development of guidelines for the management of biofilms in long pipelines to ensure the delivery of safe drinking water and to minimise impacts on water quality.

Second National Needs Survey Pegs Drinking Water Infrastructure Costs at $150.9 Billion

This column discusses the US Environmental Protection Agency's cornerstone report for constructing a plan to address the critical investment need to upgrade the nation's aging water and wastewater infrastructure. Called the 1999 Drinking Water Infrastructure Needs Survey (DWINS), the report concludes that the nation's 55,000 community water systems (CWSs) and 21,400 not‐for‐profit noncommunity water systems (NCWSs) will need to spend at least $150.9 billion over the next 20 years to pay for projects eligible for Drinking Water State Revolving Fund (DWSRF) assistance to ensure delivery of safe drinking water. This report forms the basis for revising the formula that determines how much each state receives in annual federal grants to capitalize their DWSRFs for the next four years. Besides identifying a total needs figure for the next 20 years, the 1999 DWINS report breaks the numbers down into current and future needs, needs by size and type of system and by type of infrastructure improvement, needs to achieve and maintain compliance with existing and forthcoming SDWA regulations and by individual states and territories as well as American Indian and Alaska Native communities.

Megacities from a Water Perspective

ABSTRACT Megacities, i.e., cities with more than ten million residents are growing fast. In developing countries, and especially in Africa the growth is fastest. Water-related problems in these cities are already enormous, and further degradation is expected. Water shortage is a rapidly growing problem and delivery of safe drinking water cannot be ensured. In many places municipal and industrial wastes are disposed of to the natural environment, generally without adequate treatment. Infrastructure and wastewater treatment facilities are usually by far insufficient. The present situation with respect to pollution of ail; land, and water, as well as lack of basic water and sanitation facilities in these cities creates living conditions that are nothing less than a derision of human dignity. Megacities constitute the most important source of global environmental pollution. Solution of this megaproblem of megacities requires efficient regulations and actions to stop further population growth and, in the water...