The water we use and drink travels many miles and goes through many steps in the water system as it travels from Lake Erie to homes and businesses. The journey begins at four intakes that are permanently anchored under water in the lake three to five miles offshore. Powerful pumps draw water into the system from these intakes via eight to ten foot-diameter tunnels; screens cover the places where water enters the system to keep out fish and large debris.
Water drawn into the system at the intakes is known as "raw," or untreated, water. This water travels through the intake tunnels to one of the system's four treatment plants. Here, chemicals that treat and disinfect the water are added, and sediments are removed.
After the task of making water safe for human consumption comes the challenge of delivering the water to consumers, a process known as distribution. The Division of Water delivers its product to some 400,000 customers in Greater Cleveland through approximately 5,000 miles of water mains. These mains would stretch from Cleveland to San Francisco and back if laid end to end. Not only must our water travel great distances from lake to tap, it must also move uphill to the communities at higher elevations than Cleveland and Lake Erie. Water can move uphill because of various measures. To begin with, water is pumped into pipes at primary pump stations in or adjacent to water treatment plants. This provides water pressure, which makes water move up gradual inclines and is sufficient for serving most parts of the City of Cleveland and suburban communities close to Lake Erie. However, as water moves farther from the primary pumps, pressure would fall and water would not be able to continue moving if the system did not include secondary pump stations and storage tanks. These facilities add extra boost to water traveling in mains and allow it to continue its journey to customers. The system also includes 14 towers, which serve two functions. Towers store water for a community, and provide additional water pressure and volume, most notably in the event of increased demand for fire fighting. Water is Pumped up into the tower, and when it is allowed to flow back down into the system, the weight of the water and the effect of gravity provide the energy water needs to move, supplementing water pressure. Thus several types of facilities and techniques work together to ensure that all communities served by the Division of Water enjoy high quality water, at adequate pressure.
The Supervisory Control Center in Parma Heights makes sure that all parts of the delivery system function to meet customer needs. The Center's Supervisory Control and Data Acquisition System -SCADA - is the computerized nerve center of the Systems secondary operations. SCADA is extremely important because demand for water varies according to factors such as the time of day and the season of the year. When usage in a particular area jumps, say in a residential district during the afternoon of a hot summer day when people are watering their lawns and children are playing in the sprinklers, SCADA helps the system respond and allocate appropriate amounts of water to that area. The computers' nearly instantaneous reactions and the operator's knowledge control all Pumps housed in secondary and booster stations, and can open and close secondary storage facilities, such as elevated towers, steel tanks and concrete reservoirs placed throughout the system. The system also allows the programming of actual conditions and the projection of future needs, helping the Division of Water to provide uninterrupted delivery. Should a main break somewhere in the system, SCADA can help divert water past the affected area and keep water flowing to customers. This ability to respond to system emergencies is a key reason why our water system is so reliable.