Projected annual replacement needs for transmission lines arid distribution mains 2000-2075, ( USEPA 2002a) As distribution system infrastructure ages and replacement needs increase over the following decades, infrastructure deterioration can be expected to be of more concern for drinking water utilities. and Canada found an annual average main replacement rate of 0.8 percent, in line with the rates projected in 2002 ( Folkman 2018). Data from a 2017 survey of utilities in the U.S. Replacement needs are projected to peak around 2035 with almost 2 percent of the country’s transmission lines and distribution mains in need of replacement ( USEPA 2002a). Figure 1 shows the projected annual replacement needs for transmission lines and distribution mains for each year between 20. In the United States, much of the drinking water infrastructure is approaching the end of its useful life within the next 30 years ( AWWA 2012). In this paper we focus on microbial risks associated with distribution system infrastructure, although there may be other types of risks that could affect water system infrastructure as well.ĭeteriorating drinking water distribution systems are prone to a host of problems which may increase the probability of public health issues ( Deb et al. A newer system may deteriorate rapidly, with conditions similar to those of a much older system, so that despite the difference in actual ages, the conditions and public health impacts may be the same.

For the purposes of this article, “deterioration” is taken to mean degradation due to age and normal use, but also due to inadequate maintenance, or adverse environmental or water quality conditions (e.g. This article provides an overview of relevant information about deteriorating distribution system infrastructure and suggests a conceptual framework for evaluating the potential public health impact from such deterioration.

Given that much of the nation’s drinking water distribution system infrastructure was installed 50 or more years ago, a large proportion of the infrastructure may need to be replaced over the next decades ( AWWA 2012). This can lead to increasing challenges for a historically reliable water supply and the provision of barriers designed to prevent system contamination. Much of the drinking water distribution system infrastructure in the United States has exceeded its life expectancy and is deteriorating.

Average age of water infrastructure