Calexico provides potable water service to its residential, commercial and industrial customers within the City limits. The City’s water system treats Colorado River surface water imported 80 miles from the Colorado River by the Imperial Irrigation District (IID) via the All American Canal near the Southern Pacific Railroad. Raw water is pumped through a 42-inch pipeline to the City’s 25 million gallon (MG) reservoir. The water is then pumped from the raw water reservoir through a 30-inch pipeline to the City’s water treatment plant, located at 545 Pierce Avenue, a distance of approximately one mile from the diversion point.
The existing 14 million gallons per day (MGD) surface water treatment plant is a conventional plant consisting of two up-flow clarifiers, gravity filtration, and chlorine disinfection. This water is treated in compliance with the Surface water Filtration and Disinfection Treatment Regulations found in Chapter 17 Title 22, California Code of Regulations, the California Department of Health Services, and Local Agency requirements. The level of treatment and compliance with safe drinking water requirements varies with the quality of the raw water delivered.
Treated water is stored in three above grade, fabricated steel, tanks located at the treatment plant site and the eastside reservoir. These tanks have the capacities of 6.0 million gallons per day (MG), 6.0 million gallons per day (MG) and 4.0 million gallons per day for a total of 16.0 million gallons available for distribution. The City’s total storage capacity for finished water is million 16 million gallons per day (MGD). Total storage capacity including the raw water reservoir is 41 million gallons per day.
The City has one finished water pump station at the water treatment plant (WTP), which maintains water pressure in the City. The current flow rate of the finished water pump station is 18,000 gallons per minute (GPM) or 26 million gallons per day (MGD). The discharge pressure of this pump station is approximately 62 pounds per square inch (PSI). Seven pumps (5 at main facility, 2 at east side) transfer potable water from the storage tanks to the City’s distribution system, .
The present water system is operated in one pressure zone which is sustained by pumping only. Because the topography is essentially flat throughout the City, there are no reservoirs in the system that can provide hydraulic gradient to sustain even the minimum pressures required by users. The existing water distribution system includes over 75 miles of pipelines ranging from two inches to 30 inches in diameter.
Two emergency diesel pumps that pump at 4,000 gallons per minute (GPM) to keep pressure in distribution in case of emergency.