County Report Points the Way for Potable Reuse

As a part of our work on sustainable water initiatives, including recycled water, stormwater, and groundwater protection, Heal the Ocean is closely following both short-term and long-term water supply planning efforts and as a part of these efforts we recently met with Santa Barbara County Public Works Deputy Director for Water Resources and staff to request a number of changes to the “Long Term Supplemental Water Supply Alternatives Report.” The Report was initiated at the direction of the County Board of Supervisors in order to develop information on potential sources that could supplement existing water supplies.

In discussing the Report with County staff, we proposed a list of suggested changes, including greater emphasis on the future viability of conservation and stormwater capture strategies. To the County’s credit, they adopted many of our suggestions, and we thank them for seriously considering and incorporating our input. Taken as a whole, this Report represents a significant step forward for increasing local, sustainable water supplies. More specifically, the Report provides compelling new information on the potential for advanced recycled water projects to cost effectively meet future water supply needs.

“…this Report represents a significant step forward for increasing local, sustainable water supplies.”

Conventional recycled water for use in irrigation has been a staple of diverse water supply portfolios in California for decades and, after four years of drought, water professionals continue to ask how we can maximize this resource. However, the cost of installing a separate “purple pipe” distribution system for the delivery of tertiary treated recycled water has made many recycled water projects too expensive to implement. In response, water agencies have increasingly turned to the prospect of “indirect potable reuse,” which deploys highly advanced treatment processes to transform wastewater into a source of highly treated, purified water for use in recharging groundwater supplies (see HTO’s White Paper for more on potable reuse projects).

The County’s “Long Term Supplemental Water Supply Alternatives Report” provides significant new information regarding the viability of potable reuse projects in Santa Barbara County. Most significantly, this Report developed the first estimates of project-specific unit cost and water supply estimates for a range of potential potable reuse projects across the Santa Barbara region, including eight indirect potable reuse projects and nine direct potable reuse projects, which are expected to be approved by the state in coming years.

All told, 12 projects were specifically designated for “regional consideration,” which means that the project was estimated to cost less than $3,000/acre-foot and produce more than 2,000 acre-feet per year (an acre-foot is approximately equivalent to filling up a football field with one foot of water). While many have pushed for desalination in response to the drought, the Report shows that these 12 potable reuse projects are more economical on average than the desalination options available to the County. Only one potable reuse project was found to be more expensive than the cheapest ocean desalination option. In fact, our analysis of the Report’s data shows that potable reuse options are on average $1,034/acre-foot less expensive than the five ocean desalination options considered (See Figure 1 above).

This is a huge difference: the average cost of potable reuse options ($1,346/acre-foot) is close to half the average cost of desalination options ($2,380/acre-foot). More precisely, potable reuse projects cost an average of 43.45% less than the ocean desalination options.

“…the average cost of potable reuse options is close to half the average cost of desalination options.”

The County Report demonstrates that indirect and direct potable reuse offers a cost-effective means to fight water scarcity. This locally controlled source of supply offers a compelling opportunity to meet future water needs and Heal the Ocean intends to continue to push for these options as a part of our campaign to help develop sustainable supplies of water.