Flagstaff depends entirely upon snow pack, rain, and aquifers for municipal water. After determining in 1884 the inadequacy of a single Mars Hill spring, the city constructed a twelve mile pipe to tap Schultz Pass sources. Three additional springs tapped at the turn of the century provided Northern Arizona Normal School with water since its opening in 1899. Today Upper Lake Mary reservoir provides approximately 1/3rd of Flagstaff's water, supplemented by twenty-one wells and seasonal springs.
Increasing demand has led Flagstaff to use reclaimed water since 1983. At two plants, water is screened, treated, bleached, and returned via a separate distribution system to golf courses, athletic fields, and specially equipped buildings. In 2009 reclaimed water comprised 20% of Flagstaff's water use, saving more than 650 million gallons.
In 1993, Northern Arizona University began utilizing reclaimed water. Following its 2004 expansion, this system serves all outdoor athletic fields and provides most landscape irrigation. All new buildings incorporate its use, with several older ones being converted to use it. In 2011, reclaimed water saved NAU twenty eight million gallons of fresh water.