My Water Stinks!

My old friend Jim Green at the Metropolitan Water District of Southern California apparently “pulled the short straw” and had to speak to the press about a water quality issue facing a few million people in the Inland Empire region of SoCal.  The story shows up here:

Jim and the story make it clear that the water is safe to drink — although most people would hesitate to do so.  The odor comes from blue-green algae, and these microbes are commonly found in surface waters.

This time, it appears that Silverwood Lake is the source.  Silverwood is owned and operated by the California Department of Water Resources — not MWD — so Jim and MWD are somewhat helpless to do much about this.  The algae will die off in due course, but we will have some water with an earthy-musty odor for the next couple of weeks.  As a consumer, your best recourse is to chill the water in a glass container in your refrigerator.  That’s usually the best way to deal with water odors.

Why can’t MWD just take that odor away in their treatment plants?  It’s just not that easy.  First of all, the concentration of the odorant chemicals is remarkably small — probably well less than 0.1 parts per billion!  Next, it is dissolved in the water, just like the salt in sea water.  That means removal is a challenge.

Activated carbon can be effective at removing such odors.  A small home unit should work fine.  At a treatment plant scale, though, activated carbon treatment is difficult, expensive, and fraught with operational problems.  So the best approach is often to just wait it out for the few weeks of the algae “bloom.”

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