YC resident asks: 'Why does my tap water stink?'

Q: My water stinks! I live in south Yuba City off of Bogue Road and as of the past months my city water smells rotten. The smell is so bad that my girlfriend has to plug her nose when she drinks it and then gives me the "It is time for you to move if your water doesn't start tasting better" stare. What should I do?

A: That odor, which may have Yuba City residents checking under their kitchen sinks for a dead cat, is actually a substance called geosmin, said Ian Pietz, the associate engineer in charge of Yuba City's water filtration plant.

Geosmin is an organic compound produced when blue-green algae dies. You're smelling it this year because much of Yuba City's drinking water comes from Lake Oroville, where the water level is very low. The blue-green algae lives — and dies — on the lake bottom, said Pietz.

It's not unusual at this time of the year, when temperatures in the Feather River are warmer, for Yuba City's water to smell like algae. But this geosmin stuff is a whole different kettle of fish.

Humans can smell geosmin when it reaches a level of five parts per trillion. The water coming into Yuba City's water treatment plant is at 25 parts per trillion, Pietz said.

The city is receiving many complaints, he said.

Pietz pointed us toward Wikipedia, which compares geosmin "to the strong scent that occurs in the air when rain falls after a dry spell of weather."

If you ask us, that's a very kind way of describing what another reader called a stench.

"I have turned on my shower, kitchen sink or even flushed the toilet and the smell is horrible," that reader told Since You Asked.

To combat geosmin, more activated carbon is being added to water at the plant. But there's a limit to that remedy. Any more carbon would have a negative effect on other treatment processes, said Pietz.

The good news is that geosmin is harmless to humans. And the odor can be eliminated with a home charcoal filter, he said.

Another piece of good news is that water from the plant smells less of chlorine than in years past. Pietz attributed the improvement to the addition of a four-million-gallon storage tank that alters the route that water takes during the treatment process.

So let's all hold our noses and raise our glasses in a toast — to higher water levels next year in Lake Oroville.

Since You Asked is published Tuesdays. Send questions to reporter Rob Young at the Appeal-Democrat, P.O. Box 431, Marysville CA 95901; or e-mail him at ryoung@appeal-democrat.com.