Final disinfection

The filtered water goes through one last step, secondary disinfection, to provide continuous disinfection when it is delivered to water users. Our treatment plants use chlorine and chloramine to kill any bacteria or viruses that may be present in the pipes from our plant to your tap. Chloramine is a combined chlorine and ammonia compound used to disinfect potable water.

Chlorine was first successfully used as a disinfectant for water in 1908. Chlorine disinfection has just about wiped out water-borne diseases such as cholera and typhoid in the United States. The science of water treatment has progressed so far that detection and control of contaminants in water have reduced health hazards to nearly zero.

Holding ponds where mud settles

After the water is treated, it flows through the pipelines all across the Santa Clara Valley. Your water retailer takes it from here and distributes the water.

The mud press: solids waste stream
Mud from the bottom of the clarifiers flows into the holding ponds where it settles and thickens to approximately 4 to 5 percent of solids in the water.

The mud is then pumped into a mixing tank where anionic polymer is added to cause it to coagulate or separate from the water as it is pumped onto the belt press.

Mud pumped onto a belt press

The mud is spread out on the top belt and channeled back and forth by plastic blades to allow most of the water to drain through the belts (meshed nets). The mud is then dropped onto the lower belt and sandwiched between the upper belt as it moves through a series of rollers, which squeezes out even more water.

The belt press process

The mud cake is scraped off the belt and drops onto a conveyor and deposited in an outside holding area where it is periodically hauled off to a landfill.