The cost of ocean water desalination can vary from one part of the world to another part of the world and even within the same state and only a few miles away from each other. The potential cost variances from one desal plant to another depend on a series of factors, some of which are listed below.
  • Project procurement method (design/bid/build, design/build/operate, etc)
  • Who owns the project (public agency, private company, public private partnership, etc)
  • A water purchase agreement (take or pay agreement, etc)
  • Financing of the project (low rate bonds, private investors, etc)
  • Water quality objectives set forth by the drinking water regulators
  • Quality of ocean water coming into the plant
  • Choice of intake systems (subsurface, screened intake, etc)
  • Choice of on-site treatment and technology
  • Length of time the project is financed
  • Percent of desal water to be supplied to the service are (100% desal, 50% desal-50% imported water, etc)
  • Cost of power to the desal plant
  • Location of the plant (ability to utilize existing infrastructure, etc)
  • Numerous others…

With the almost unlimited factors that can affect the cost of ocean water desalination West Basin has completed several cost estimates and impacts to rate payers. The West Basin board first evaluated ocean water desalination and compared the cost to imported water sources through Metropolitan Water District and discovered ocean water desalination was 30x more expensive that imported water. Over the years advancements in technology, energy recovery, optimization and increasing imported water rates have helped ocean water desalination become a more feasible water supply option.

In addition to comparing the cost of ocean water desalination over the years, comparing the cost of ocean water desalination to other water supply options has been performed. West Basin has operated a recycled treatment plant and program since 1990 and has compared the costs of ocean water desalination to the different grades of recycled water produced. On average, a 20MGD ocean water desalination facility would cost approximately $1,800/Acre-foot in comparison to an average of the five types of recycled water qualities West Basin produces at approximately $1,500/Acre-foot. If a larger plant is built, economies of scale provides a benefit and the total project cost drop so about $1,600/Acre-foot. West Basin has estimated the average increase on a monthly water bill to introduce a 20MGD desalination facility would be approximately $3.00/month, or the price of a Starbucks coffee.

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