Saturday, October 23, 2010

Water recycling is a great idea; water desalination has serious problems

I've been asked a number of times about my opinion on water recycling. I think it's a great opportunity to do more with our existing water supply, rather than constantly searching for new water sources. Water recycling treats used water so it can be reused, currently for landscaping and agriculture (the "purple pipe" we see increasingly in various parts of the County is the separate piping system for recycled water).

It certainly makes much more sense to use recycled water instead of drinking water on landscaping and farmland. The next stage, something already done in southern California, is to purify recycled water and pump it back into the groundwater table, where we can fully reuse it.

So I support the existing programs for recycled water, and the role it has in the Water District budget will allow recycled water to expand. I'd also be interested in even more expansion, but I don't see the Water District's budget expanding anytime soon, so we'd have to figure out where the money would come from to accelerate the process.

Desalination (the process of converting saltwater to freshwater), by contrast, has some significant problems. A huge amount of energy is consumed in the desalination process, making it both expensive and environmentally problematic. The remainder of desalination is a soupy salt brine that creates a big disposal problem, especially for us bordering the shallow San Francisco Bay. Any approach to desalination would have to be done very carefully.

Finally, while I distinguish between water recycling and desalination, the distinction is really a matter of degree. Recycling also consumes energy and also has leftover materials. But being able to think in shades of gray is an important part of policy, which is why water recycling should be more encouraged than desalination. Most important of all though is water conservation, reducing the initial demand, and we can still do a lot more on this issue.

1 comment:

  1. The SCVWD Water Utility Enterprise Report for FY 2010-11 shows planned capital expenditures of $282 million for Source of Supply over the next 10 years. Of that total, only $22 million is for recycled water, and that is planned to be spent in the next three years, than NOTHING after that.

    All the rest of the of the capital projects are maintenance and payments for existing facilities which will produce no extra water, and possibly less than they have produced historically.

    The Water District must focus its capital program on building new, local, reliable supplies and stop throwing good money after bad. Recycled water and desalination are the only real new supplies available. And I agree with your statements above about desalination's more costly impacts. So Where's the beef? Build more capacity for recycling and stop using it as green washing for the District's water portfolio.

    Pat Ferraro, Former Director, SCVWD 1972-1995