Basic Information

Drinking water systems that serve fewer than 10,000 people are considered "small systems" and most are privately owned. Small systems face unique challenges when it comes to compliance with the Safe Drinking Water Act and its major 1996 amendments. For many reasons, including economic ones, it is difficult for small systems to keep pace with the rapidly expanding regulatory mandates. Technical applications are often inappropriate for small systems. In addition, basic infrastructure repair and replacement are needed.

The 1996 amendments to the Safe Drinking Water Act provided exemptions for small systems that encounter compelling economic circumstances. Still, small systems must be able to enhance their technical, managerial, and financial capabilities in order to serve their customers safe, clean drinking water.

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Small System Challenges

• Small system infrastructure may be outdated and in poor condition, and because most of the distribution system is located under ground, detecting and solving problems (such as leaks and pipe deterioration) are made more difficult.
• Source water available to small systems may be of poor quality and limited quantity.
• Technical expertise necessary to evaluate and install new treatment technologies may be lacking.
• A small customer base means small system utilities face considerable financial challenges. Consequently, small systems often lack the opportunity to benefit from economies of scale.
• Despite the obvious need for source water protection, just 28 percent of the smallest systems and only 50 percent of systems serving 10,000 or more persons participate in some form of source water or wellhead protection program. Some small systems are less likely to adopt wellhead protection or source water protection programs because of the lack of technical and financial resources to implement and manage such programs.

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Source Water Issues

Our drinking water comes from surface water (streams, rivers, lakes) or groundwater (aquifers). Ground water is the main source for over 90 percent of public water systems and a majority of those using groundwater are small systems.

Source water moves within a watershed via overland flow (that is, surface water), shallow subsurface storm flow, or groundwater flow. Surface water is vulnerable to contamination from surface runoff and groundwater infiltration. Ground water is vulnerable to contamination through infiltration from the surface, incursion of contaminants from underground storage tanks, septic systems, injection wells, and by naturally occurring substances in the soil or rock through which the water flows.

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Treatment Technologies

Water is the universal solvent, and most materials eventually dissolve in water. Even so, water found in nature does contain a variety of contaminants that enter the water either through natural processes or via human and animal wastes. These wastes are the primary contributors to microbiological contamination of water. In addition, industrial and agricultural sources can introduce chemical, pesticide, and herbicide residues into water.

Today, there's an emphasis on disinfection and filtration technologies that remove contaminants from water. For harmful levels of contamination, disinfection is usually achieved by applying chlorine or commercial bleaches. Combined filtration/disinfection treatment is usually sufficient to remove visible contaminants and kill most bacteria and viruses. However, too little filtration and disinfection can result in a higher risk of a wide variety of stomach and intestinal illnesses. Too much disinfectant with too little filtration can result in the formation of disinfection by-products and a higher risk of cancer. So it is important to have technologies in place to monitor and enhance the treatment system operation, thereby improving the overall water quality provided to consumers.

Technologies can be packaged together to provide an affordable solution for small system operators who may not otherwise be able to efficiently treat their water. EPA has evaluated several of these commercially available, prefabricated "package plants" suitable for small systems.

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Distribution Systems Issues

Distribution systems deliver water from a source (usually a treatment facility) to consumers in a utility's service area in the required quantity at a satisfactory pressure. To do this, the distribution system needs storage tanks or reservoirs, pipes, pumps, valves, and other components. This infrastructure is the most valuable asset of a water utility, and most of it is under ground or inconspicuously located.

Proper operation and maintenance of distribution systems is key to ensuring that safe drinking water is provided to consumers. This includes three broad issues:

• Aging water infrastructure repair and rehabilitation
• Operational concerns, such as biofilm growth, disinfection by-product formation, nitrification, and improper storage of finished water
• Contamination vulnerabilities, such as cross connections, permeation and leaching, and intrusion and infiltration

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