|From the American Water Works Association 2011|
In most of our communities and cities we inherited the water infrastructure which was built by previous generations. This water storage, treatment, and distribution system delivers as much water as we want whenever we want it (under most circumstances). This amazing infrastructure to deliver 24/7 water was built beginning in the late 19th century and throughout much of the 20th century. We have barely thought twice about our water and have taken for granted the capital investment made by those previous generations. The water bill that most pay barely covers the cost of delivering the water and some repairs. No infrastructure lasts forever and we have failed to properly maintain and plan for the orderly replacement of the water distribution systems. In the United States we have never experienced the need for pipe replacement on a large scale and have taken for granted what we were given. However, in our cities water mains are failing at an ever increasing rate.
The water distribution systems in most of our big cities have reached the end of their useful life. As documented by the U.S.Environmental Protection Agency Drinking Water Needs Survey and Assessment 2007 and the American Water Works Association, AWWA, report: “Buried No Longer:Confronting America ’s Water Infrastructure Challenge” a large proportion of US water infrastructure is approaching, or has already reached, the end of its useful life. The need to replace or rebuild the pipe networks that deliver water comes on top of other water investment needs, such as the need to replace water treatment plants, upgrade treatment technology to respond to emerging contaminants in our raw water supplies, replace storage tanks and on-going monitoring and compliance costs. The investment needs for our wastewater and stormwater systems will also have to be addressed for those systems are old as well.
According to the AWWA, restoring existing water systems as they reach the end of their useful lives and expanding them to serve a growing population will cost at least $1 trillion over the next 25 years in 2010 dollars, if we plan to maintain 24 hours per day on demand of water service for our country. The AWWA analysis includes investments that will be necessary to meet projected population growth, regional population shifts, and service area growth over that period. The EPA estimates that the twenty-year capital improvement needs for infrastructure investments necessary from 2007, through 2026, for the existing water systems to continue to provide safe drinking water to the public to be $335 billion assuming no growth in service area and no population shift. EPA’s “Clean Water and Drinking Water Infrastructure Gap Analysis,” actually estimated drinking water systems’ 20-year capital needs in the range of $204 billion to $590 billion with a point estimate of $335 billion, the always cited cost. The EPA costs exclude maintenance and replacement of dams and reservoirs because they are excluded from the EPA’s Drinking Water State Revolving Fund, DWSRF, funding. The smallest systems actually have the highest cost per person for pipe replacement because the residences are more spread out- there are more feet of pipe main per residence and the EPA’s data may be weakest in that category.
The EPA estimate for total national need of $335 billion in 2007 is comparable to the 2003 estimate of $331 billion (as adjusted to 2007 dollars). Indicating that no progress has been made in the long term replacement and during the period 2003-2007 only repairs seem to have been made. Both the 2003 and 2007 EPA Assessments and the AWWA assessment clearly point to the nation’s water systems having entered a “rehabilitation and replacement era in which much of water utilities’ existing infrastructure has reached or is approaching the end of its useful life.” It is to be noted that no real progress has been made in water infrastructure replacement since 2007.
We are living with aging drinking water infrastructure, with increasing incidence of unplanned failures. We can continue to respond to water emergencies or, we can carefully prioritize and undertake drinking water infrastructure renewal investments to ensure that our water utilities can continue to reliably and cost-effectively support the public health, safety, and economic vitality of our communities. The choice is ours and will be made community by community. According to the EPA, water utilities in the United States is highly fragmented with approximately 52,000 water systems with 56% of that number serving populations of 500 or less. The large number of relatively small systems may not have the expertise to analyze a system and develop a replacement plan and may not have the financial capability to raise capital independently. However, smaller systems can more easily vote for capital surcharges and may be eligible under the DWSRF. The Safe Drinking Water Act, as amended in 1996, established the DWSRF to make funds available to drinking water systems to finance infrastructure improvements. The program emphasizes providing funds to small and disadvantaged communities and to programs that encourage pollution prevention as a tool for ensuring safe drinking water.
How will all this money be spent? Transmission and distribution pipes, pumps and valves represent about 60% of the projected cost of replacement and rehabilitation. Although the least visible component of a water system, the buried pipes of a transmission and distribution network generally represent most of a system’s capital value. Even small rural systems may have several hundred miles of pipe. In larger cities, replacement or rehabilitation of even small segments of the extensive underground networks of water supply pipes can be very costly, due not only to the cost of construction but also the costs related to disruption to the city’s traffic and business. Replacement projects for water mains, valves and pumps present such challenges that they are typically only undertaken after failure driven by a utility’s need to continue providing potable water to its customers while preventing contamination of the water prior to delivery.
The rate at which water mains fail varies greatly by type of pipe, age of the pipe, water characteristics, soil characteristics, weather conditions, and construction methods. Some pipe materials have been found to degrade prematurely; galvanized pipe has turned out to be particularly susceptible to corrosion in certain soils, and unlined cast iron pipe is susceptible to internal corrosion. Asbestos cement pipe presents challenges to protect workers during pipe repairs. Currently, many water systems are using ductile iron or polyvinyl chloride pipe (PVC) for construction and replacement now. It remains to be seen how long this infrastructure will last.
The EPA estimates that 22% of the costs of water infrastructure rehabilitation will have to be spent on treatment and compliance. Treatment facilities vary across systems depending on the quality of their source water and type of contamination present. Treatment systems can range from a simple chlorination for disinfection to a complete conventional treatment system with coagulation and flocculation, sedimentation, filtration, disinfection, laboratory facilities with computer automated monitoring and control devices. This also includes projects to remove contaminants that affect the taste, odor, and color of drinking water, but are otherwise harmless (or almost so). These costs may increase due to deterioration of source water quality.
Source water infrastructure is estimated at about 6%. This includes constructing or rehabilitating surface water intake pumps and pipes, drilled wells, and spring collectors. Drinking water comes from either ground water or surface water sources. Wells deliver groundwater. Rivers, lakes, and wells in karst terrain under the direct influence of surface water are considered surface water sources. A high-quality water supply can minimize the possibility of microbial or chemical contamination and may not require extensive treatment facilities. Many of the source water needs involve construction of new surface water intake structures or drilling new wells to obtain higher quality raw water to minimize the treatment costs.
The remaining 12% of water infrastructure needs are attributed to storage and miscellaneous other projects. Storage includes projects to construct, rehabilitate, or cover water storage tanks, but it excludes dams and raw water reservoirs because they are specifically excluded from DWSRF funding. A water utility cannot function without sufficient storage to provide adequate supplies of treated water to the public, particularly during periods of peak demand. This storage allows the systems to maintain the minimum positive pressure required throughout the distribution system to prevent the intrusion of contaminants into the (deteriorating) distribution networks which are not “water tight.”