When treatment is complete, the water from the Water Treatment Plant (WTP) is pumped to homes, schools, and businesses in Ann Arbor as well as to Ann Arbor and Scio townships for resale to their customers. The City supplies water to approximately 125,000 people and has an average day demand of 14 million gallons per day (approximately 5 billion gallons of water a year).
The WTP manages the City’s water distribution system, which is comprised of five pressure districts within the city. The main reservoir, three outlying reservoirs, four remote pump stations and two elevated tanks supply these districts.
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Pressure Districts
Potable water is produced at the WTP and stored in the main reservoir. The city is divided into five pressure districts that are supplied water from this reservoir by a variety of means. The five districts are:
Gravity Pressure District
The gravity district is the central part of the city, this includes downtown, the old west side, central campus, Burns Park. Since the elevation of the main reservoir is very high above this area, water is supplied to the district without pumping.
West High Service District
The West High Service district is the west side of the city. It is west of State Street on the south, west of Spring Street on the north and of course west of the Gravity District. The district is supplied water from the WTP via West High Service pumps at the plant and supplemented by a storage reservoir and pump station. There is no elevated water tank in this district so pressure is maintained by constant pumping and is controlled by release of water into another district through a remote controlled valve. Scio Township is supplied from the water in this district.
North East High Service District
The Northeast High Service district is largely north of the Huron River and east of North Main and M-14. The district is supplied water from the WTP via East High Service pumps at the plant and supplemented by a storage reservoir and pump station. The water pressure in this district is regulated by the height of the water in the 0.5 MG elevated tank. As water is used in the district the water level in the elevated tank drops. When a trigger level is reached a pump is turned on at the pump station and the elevated tank is refilled. Furthermore, water can be released from this district into the neighboring district through a remote controlled valve. Ann Arbor Township is supplied from the water in this district.
Geddes High Service District
The Geddes High Service District is bounded by Washtenaw Avenue on the west and south, the Huron River on the north and US-23 on the east. East High Service pumps at the WTP provide water to the district. Secondly, a booster pump station pumps water from the gravity district into the Geddes district. The supply to the district is supplemented by water flowing through a remotely controlled valve that connects Geddes High Service district to North East High Service district.
South East High Service District
The South East High Service District is south of Washtenaw/Stadium and east of State Street. The main source of supply to this district is a storage tank within the district. There is a pump station associated with the storage tank that pumps water into the district from the storage tank. The water in the storage tank is replenished by water from the Gravity district under gravity pressure. The supplementary source of supply is a remote valve that connects this district to the West High Service district. The water pressure in the South East district is regulated by the height of the water in the 0.5 MG elevated tank within this district. As water is used in the district the water level in the elevated tank drops. When a trigger level is reached a pump is turned on at the pump station and the elevated tank is refilled. |