Woodside: Ungainly device protects drinking water


Click on picture to enlarge.

By Dave Boyce

Almanac Staff Writer

Compared to its cousins the fire hydrant and the garden faucet, the waterline backflow preventer is ungainly and unfortunately named, but what's in a name? The backflow preventer guards the public's drinking water from contamination from homes, businesses and institutions.

Reverse flow is the problem. In a serious house fire, for example, firefighters could draw so much water out of the water main that stagnant water in residential wells or sprinkler and irrigation systems might be sucked into the public main. Enter the backflow preventer, a pipe with one or more check valves that prevent flow reversal.

But do the preventers with their prominent pipes and valves need to stand out so in the natural landscape, the Woodside Town Council wanted to know. The council at its Jan. 25 meeting discussed a zoning code amendment to allow them in setbacks. Representatives from the California Water Service Corp. and the Woodside Fire Prevention District attended.

"There are some ugly ones in the town," Denise Enea, fire marshal for the district, admitted.

Because they have such a vital role, the law requires that preventers be above ground, near the road and inspected annually. Proximity to the road allows the public to see leaks and call the water company, said Tony Carrasco, manager of Cal Water's Bear Gulch district, which provides drinking water to Woodside, Portola Valley, Atherton and Menlo Park.

Cal Water prefers that the devices be as close to the main as possible, which means at or near the property line, Mr. Carrasco said. The preventers can be moved further in but only if the buried water line connecting to the main is made inaccessible with a thick jacket of concrete or a sturdy metal or PVC sleeve.

Such protection discourages ambitious plumbers looking for a place, any place, to tap in -- a nagging problem, apparently. "Maybe that would deter them," Mr. Carrasco said in an aside. "Maybe they would communicate with the homeowner a little bit more."

Roads with a view

Opinions differed as to the impression made by backflow preventers from the perspective of a passing vehicle.

"These things are not that big," said Councilman Dave Tanner, a builder.

"They are. They're huge," said Councilman Peter Mason, an architect.

Ninety percent of Woodside homes use water lines of 2 inch diameter or less, said Cal Water Assistant District Manager Paul Molder, but there are estates that need larger pipes. Shielding options include landscaping, fabric jackets and fake rocks.

In considering the appropriate setback, the council discussed linking the maximum distance from the road to the size of the water line. Pipes of up to 2 inches in diameter could have up to 10 feet, while larger ones could be allowed 25 feet to 30 feet.

"The key thing here is we don't want them right on the road," Councilman Dave Burow said.

Which houses will require one? Cal Water tends to want them on sites that can expose water to contaminants. Examples include an unapproved well or any container in which water can become stagnant, including swimming pools and fire sprinkler and irrigation systems, Mr. Carrasco said.

"Nothing from the (state) Department of Health indicates that every property will need one," he told the council. "If we see somebody that has a well and no device, we will contact them and work with them and educate them."

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Like this comment
Posted by Menlo Voter
a resident of Menlo Park: other
on Feb 11, 2011 at 7:50 pm

For crying out loud. Plant a couple plants on either side of the device. These things are important to the quality of our drinking water.

Like this comment
Posted by acomfort
a resident of Menlo Park: Suburban Park/Lorelei Manor/Flood Park Triangle
on Feb 14, 2011 at 2:41 pm

How about a challenge to your Woodside artists, gardeners and tinkerers to figure out a solution?

There must be no end of ideas to improve the looks of this ungainly device device so you can protect the beauty of your town while you protect your drinking water.

Like this comment
Posted by been there
a resident of Atherton: other
on Feb 14, 2011 at 3:30 pm

Based on the new state law passed recently, I have to put these expensive devices, retroactively, on property I own. The expense to property owners at large is immense when compared to the benefit it serves the population. These costs are passed onto tenants who pass it on to the consumer, you and me.
I have never heard of any illnesses caused from the situation these backflow preventers are designed to prevent.
It smells more like a plumber’s union has more interest in this new state law than any public health officials.
I am not stating that someone can’t find a documented situation where a backflow preventer would have prevented an actual health problem, only that the cost is not weighed against the benefits.

Like this comment
Posted by Menlo Voter
a resident of Menlo Park: other
on Feb 14, 2011 at 6:31 pm

been there:

define "huge cost."

Like this comment
Posted by Observer
a resident of Woodside High School
on Feb 16, 2011 at 9:06 am

with the mandate for sprinklers in all new construction, does Mr Carrasco's second to last paragraph mean that these are coming everywhere?

I agree that there is an opportunity for a design challenge, even if only to break away from the utilitarian color coding. Why must they be above ground, for instance?

Like this comment
Posted by Dave Boyce
Almanac staff writer
on Feb 17, 2011 at 10:18 am

Dave Boyce is a registered user.

This question of whether all new construction will require backflow preventers came up at the Jan. 25 Woodside Town Council meeting.

While all significant new construction will require interior sprinklers, Tony Carrasco of Cal Water asserted that not all those projects will require waterline backflow preventers.

That question will be answered project by project by Cal Water.

One way to avoid the need for a backflow preventer, Mr. Carrasco said, is to install a "looped" type of sprinkler system that continually refreshes its water supply.

(Traditional sprinkler systems apparently have the same water sitting in them for long period of time, allowing it to become stagnant and potentially dangerous.)

A looped sprinkler system notwithstanding, if the property also has a well or a swimming pool, Cal Water may consider a backflow preventer necessary.

As for preventers being above ground, when they were allowed below ground there were cases in which the vault flooded, Mr. Carrasco said. The devices were then immersed in water that could have been tainted. Not good, he said.

Posted by Name hidden
a resident of Atherton: West of Alameda

on Sep 25, 2017 at 3:26 pm

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Posted by Name hidden
a resident of Atherton: West of Alameda

on Sep 26, 2017 at 1:10 am

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