TABLE 9-6 Estimates of Costs of Southern California Water Supply Alternatives

Water Supply Alternatives Initial Capital Costs (million $) Annual O&M Costs (million $) Annualized Costs Over 30 Years ($/kgal)

Urban water conservation

0 0.5 0.64

Local stormwater capture

40-63 1-3.5 1.10

Potable reuse

480 30 3.10

Ocean desalination

300 37 3.10+

Brackish groundwater desalination

24 0.7 2.30-3.68

Transfers: agriculture to urban

na na 2.10+

Groundwater storage

68-135 13 1.80

Surface storage

2,500 7.5-15.5 2.30-4.30

SOURCE: Freeman et al. (2008).

customers are willing to spend. In these cases, utilities must balance the need to attract customers with the costs of further subsidizing reclaimed water.

Special negotiated rates may also be considered for large customers who provide a guaranteed steady demand over an extended period of time (e.g., large industries). These customers offer an advantage of constant demand throughout the year and practically guaranteed demand for reclaimed water from one year to the next. However, customers that require a reliable supply of reclaimed water at all times may lead to increased costs for the utility if additional infrastructure must be installed to provide uninterrupted service (e.g., a redundant distribution system or provision of an alternate water supply) (Holliman, 2009).

CONCLUSIONS AND RECOMMENDATIONS

Financial costs of water reuse are widely variable because they are dependent on site-specific factors. Financial costs are influenced by size, location, incoming water quality, expectations, and/or regulatory requirements for product water quality, treatment train, method of concentrate disposal, extent of transmission lines and pumping requirements, timing and storage requirements, costs of energy, interest rates, subsidies, and the complexity of the permitting and approval process. Capital costs in particular are site specific and can vary markedly from one community to another. The lowest cost water reuse systems supply nonpotable reclaimed water to irrigation or industrial cooling operations located in close proximity to the wastewater treatment plant. Data on reuse costs are limited in the published literature, although the chapter provides reported capital and O&M costs for nine utilities (representing 13 facilities) that responded to a committee questionnaire.

Distribution system costs can be the most significant component of costs for nonpotable reuse systems. Projects that minimize those costs and use effluent from existing wastewater treatment plants are frequently cost-effective because of the minimal additional treatment needed for most nonpotable applications beyond typical wastewater disposal requirements. When large nonpotable reuse customers are located far from the water reclamation plant, the total costs of nonpotable projects can be significantly greater than potable reuse projects, which do not require separate distribution lines.

Although each project’s costs are site specific, comparative cost analyses suggest that reuse projects tend to be more expensive than most water conservation options and less expensive than seawater desalination. The costs of reuse can be higher or lower than brackish water desalination, depending on concentrate disposal and distribution costs. Water reuse costs are typically much higher than those for existing water sources. The comparative costs of new water storage alternatives, including groundwater storage, are widely variable but can be less than those for reuse.

To determine the most socially, environmentally, and economically feasible alternative, water managers and planners should consider nonmonetized costs and benefits of reuse projects in their comparative cost analyses of water supply alternatives. Water reuse projects offer numerous benefits that are frequently not monetized in the assessment of project costs. For example, water reuse systems used in conjunction with a water conservation program can be effective in reducing seasonal peak demands on the potable system, which reduces capital and operating costs and prolongs existing drinking water resources. Water reuse projects can also offer improved reliability, especially in drought, and can reduce dependence on imported water supplies. Depending on the specific designs and pumping requirements, reuse projects may have a larger or smaller carbon footprint than existing supply alternatives. They



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