The volume of water required per foot of wellbore appears to be decreasing as technology and methods improve over time. Drilling performed with an air mist and/or water-based or oil-based muds for deep horizontal well completions. Cumulatively, hydraulic fracturing activities in the United States used on average 44 billion gallons of water a year in 2011 and 2012, according to the US Environmental Protection Agency's analysis of data from the FracFocus Chemical Disclosure Registry. Water for drilling and hydraulic fracturing of these wells frequently comes from surface water bodies such as rivers and lakes, but it can also come from groundwater, private water sources, municipal water, and reused produced water. Water use is water withdrawn from groundwater or surface water for a specific purpose. In the case of hydraulic fracturing, water can be consumed by the loss of injected water to subsurface zones or via underground disposal of wastewaters, among other means.