Save. Water used in the home comes from surface sources such as lakes and rivers and from groundwater sources such as wells. As of 2010, the average water usage per person averages 70 gallons per day, according to the American Water Works Association.ave. Water used in the home comes from surface sources such as lakes and rivers and from groundwater sources such as wells. As of 2010, the average water usage per person averages 70 gallons per day, according to the American Water Works Association.