The San Francisco Chronicle reports on the unintended consequences of San Francisco’s efforts to encourage installation of more low-flow toilets. Among other things, the city’s PUC offers rebates for “high efficiency toilets,” which use even less water than federally mandated low-flow toilets. From the Chronicle:
Skimping on toilet water has resulted in more sludge backing up inside the sewer pipes, said Tyrone Jue, spokesman for the city Public Utilities Commission. That has created a rotten-egg stench near AT&T Park and elsewhere, especially during the dry summer months.
The city has already spent $100 million over the past five years to upgrade its sewer system and sewage plants, in part to combat the odor problem.
Now officials are stocking up on a $14 million, three-year supply of highly concentrated sodium hypochlorite – better known as bleach – to act as an odor eater and to disinfect the city’s treated water before it’s dumped into the bay. It will also be used to sanitize drinking water.
That translates into 8.5 million pounds of bleach either being poured down city drains or into the drinking water supply every year.
So, while the city has reduced annual water use by an estimated 20 million gallons, it has come at a significant cost, economic and potentially ecological as well.
UPDATE: In a letter to the editor of the Chronicle (scroll down), a PUC representative maintains that they are not dumping any bleach into the bay, and that bleach is only one of several methods they use to control sludge odors.