(Norman Allenby wrote this guest column)

Leonardo Da Vinci had a relevant thought on this subject. His Ideal City postulate #6 states, “ Require that each house have its own sewerage system and be built on aesthetic and environmental principles with access at ground level.” The Da Vinci challenge is to design such a system, not just for homes, but buildings, subdivisions, shopping centers and micro watersheds that comprise greater San Diego. Homes, buildings, subdivisions, shopping centers are all parts of our urban water shed. They each take in water and give back wastewater. With each having its “own sewerage system,” the Da Vinci challenge would be met and the opportunity for onsite recycling created.

Under our present integrated water management system there is insufficient recognition of the potential for on site reuse of water. We have done a great job in corralling water from Imperial County to augment waters received from the Metropolitan Water District. We largely ignore storm water allowing it to contaminate our beaches. We discharge 180 MGD of wastewater into the Pacific Ocean at our Point Loma treatment facility. We continue to delay the intended use of the North County reclamation plant’s reclaimed water, augmenting San Vicente reservoir. We do distribute a modest amount of reclaimed water for irrigation through our purple pipe system, but our wastewater is largely wasted. That waste can be avoided through an ecological approach to water management.

Ecologically integrated water management utilizes process water, storm water and “waste water”. It first calculates how much water a facility needs, how much storm water is site available and how much “waste water” is site available. Any deficit between site available water and needs is met by process water purchased from the local provider. The focus of ecological water management is conservation and reuse and, yes, more reuse.

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