Saving water means using more bleach?

From local news outlet KTVU:


City Considers Buying Bulk Bleach To Squash Sewage Odor


Posted: 8:50 pm PST February 18, 2011Updated: 3:55 pm PST February 19, 2011

SAN FRANCISCO, Calif. -- San Francisco's efforts to conserve water have had one adverse effect on the city - a powerful stench.


To combat the smell, the city plans to purchase 27 million pounds of bleach. City officials said it's an old fashioned solution for a smelly problem.


Even during Friday's storm, San Francisco residents said they could still smell the odor


Mary Wujek, a San Francisco resident, said she noticed the smell and described it as a briny sea smell.


To help wipe out the sulpher-like smell, the city plans to spend $14 million to buy three years worth of sodium hypoclorite, also known as bleach.


The San Francisco Public Utilities Commission plans to release the 27 million pounds of bleach from tanks into the city's vast sewage system.


"It is metered in with a metering pump," said Tommy Moala, SFPUC Assistant General Manager. "Depending on the flow if needed the flow. If needed, we can put more in."


Over-the-counter laundry bleach is 6 percent sodium hypochorite. The bleach used in the county sewers is 12 percent.


The county's public utilities commission said sewage stink is particularly bad during dry, warm months.


The increased use of low flow toilets means there's less water in the sewers to dilute the smell of waste and help convey it to treatment plants.


"So as we go from seven gallon flushes to one gallon flush, it does have an effect," Moala added.


The SFPUC also uses chlorine on treated sewage water. Before it goes out into the bay, the agency also neutralizes the chlorine because it's hazardous to fish and other wildlife in the bay.


The county's board of supervisors will make a final decision on the big bleach buy on March 1.

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