secure will require policies that will ensure fair distribution of existing water sources, protecting water sources from becoming depleted, maintaining good wastewater disposal, and maintaining existing water infrastructure. Currently there are no national limits for US groundwater or surface water withdrawal. If limits are imposed, the people most impacted will be the largest water withdrawers from a water source. In 2005, 31% of US water use was for irrigation, 49% was thermoelectric power, public supply 11%, industrial was 4%, aquaculture 2%, mining 1%, domestic 1%, and livestock less than 1%. Pollution An important turning point in managing drinking water contamination occurred after passage of the 1974 SDWA, which required the National Academy of Sciences (NAS) to study the issue. The NAS found that there really was not a lot of information available on drinking water quality. Perhaps the most important part of the study, according to senior EPA officials responsible for implementing the 1974 law, was that it described some methodologies for doing risk assessments for chemicals that were suspected carcinogens. According to the 2015 US census, one-fifth of all households are not connected to a community sewer system. Furthermore, many households have wastewater disposal systems that have inadequate treatment, such as sewage systems directly piped to nearby bodies of water and septic systems leading to fecal contamination. For example, in Barry-Easton District, Michigan 10% of the state's 1.3 million on-site wastewater treatment systems are malfunctioning, causing sewage to be running into the lakes and streams. This pollution of water is contributed to several health concerns in the US, especially for minorities and low-income individuals. In Lowes County, Alabama, hookworm is affecting people today due to unsanitary waste disposal. 73% of residents reported to have sewage running into their homes and 34% of residents surveyed tested positive for hookworm. These contaminated bodies of water also directly affect drinking water supplies, habitats and recreational sites, creating more issues for the environment. Overall, the cost to replace failed sewer systems and remove fecal waste from the water is typically higher than placing alternative infrastructure and maintaining adequate functioning systems. Sewer overflows Combined sewer overflows (CSO) and sanitary sewer overflows affect the quality of water resources in many parts of the U.S. About 860 communities have combined sewer systems, serving about 40 million people, mostly in the Northeast and the Great Lakes Region. CSO discharges during heavy storms can cause serious water pollution.