Well-head treatment provides drinkable water that also can be
used for animals, gardening
The most hopeful estimates for scrubbing perchlorate from the underground water table run at least 20 years, but there are ways for property owners to clean their own water without relying on the company that contaminated it.
For less than $200, homeowners whose well water is contaminated can purchase a filter certified by the state’s Department of Health Services to remove 96 percent of the perchlorate from the water flowing through the filter.
The device also has been endorsed by the Santa Clara Valley Water District, which included it last week in a suggested cleanup plan it forwarded to the state’s Central Coast Regional Water Quality Control Board. The District hopes that the Regional Board will compel Olin Corp. – the company responsible for the 10.5-mile perchlorate plume stretching south from Tennant Avenue in Morgan Hill – to adopt its plan.
The plan calls for Olin to provide filtration systems to the users of about 850 wells to whom it currently provides bottled water. An annual supply of bottled water for a family of four costs about $730, and some homeowners are left to bear the costs.
Christina Bentley moved from Milpitas to San Martin with her family in March. The water coming into her home is contaminated, but not at a level forcing Olin to provide water. After paying a $125 a month for water service, the Bentleys two weeks ago installed a filter.
“The tap water is disgusting. I don’t want my family drinking it,” she said. “The filter is working very well and now the water is tasty.”
But as effective and relatively inexpensive as the filter is, it has many drawbacks.
“It’s pretty cheap and easy, but we would like a longer-term solution,” said Tracy Hemmeter, a senior project manager at the Water District. “The ideal would be treatment at the well head.”
Well-head treatment is important, said Tom Mohr, a geologist with the Water District, because water treated at the well is available for all potential uses. It is drinkable and can safely be used to care for animals and for gardening. Contaminated water is particularly hazardous for edible row crops because many vegetables retain perchlorate over successive waterings.
“The concern about perchlorate accumulation in food crops is real,” Mohr said.
But there are no certified treatment systems that can be used on wells. Municipalities can get permits for treatment of public wells, but expensive well treatments will not be installed before they are certified by the state. Although the Regional Water Board can order Olin to cleanup the plume and provide potable water, the company has wide latitude in choosing how it meets goals.
The filter certified for use under the sink is manufactured by Phoenix-based Watts Premier. The unit works through reverse osmosis. Water rushing up through the pipes is trapped by a semi-permeable membrane, which traps water molecules but not molecules of perchlorate and other contaminates. Pressure in the filter forces clean water into a three-gallon holding tank and pushes the contaminated water up through the faucet, down the drain and back to a water treatment facility.
No one knows if septic treatment cleans perchlorate, but septic treatment plants operate without oxygen, a friendly breeding environment for the kind of bacteria that destroy perchlorate.
Another drawback is that the sink system is not very efficient. A Watts Premier spokesman said that it takes three or four gallons of water to make one gallon of clean water, but some water officials place that number as high as eight.
And there are complications for people who want Olin to buy and maintain their filter. Olin is not likely to accept liability for the filters unless the company has some way to service and monitor them.
Sylvia Hamilton, president of the San Martin Neighborhood Alliance and chairwoman of the Perchlorate Community Advisory Group, said last week that people who want filters in their homes should buy them themselves.
“We’re more interested in pursuing well-head treatment from Olin,” Hamilton said. The reverse osmosis system is inexpensive enough that people can get one relatively inexpensively,” she said. “If I was (Olin) I would not want to pay for it and be liable for a service that I don’t have easy access to.”
The company does have easy access to wells. Olin could not be reached for comment, but a spokeswoman for U.S. Filter Corp. in Chicago said that that company is working with Olin to develop a reverse osmosis filtration system for use on private wells. It’s not clear when well treatment might be certified.
Another option is a filter that treats water before it enters the house and delivers uncontaminated water to every faucet in the house, but such a system is significantly more expensive than an in-house filter, and Mohr said treating the water that way causes a marked loss of water pressure and leaves water from other sources untreated.
Though products made by Watts Premier are the only ones certified by California, all osmosis filters will remove perchlorate from water. However, there’s no data that characterizes the effectiveness of other brands.
Matt King covers Santa Clara County for The Dispatch. He can be reached at 847-7240 or mk***@gi************.com/
