May 2007
A pitcher to skip
Lotus Tersano
The Lotus Tersano pitcher, $150 (www.tersano.com), is the first water filter we’ve tested that claims to sterilize water using ozone. Though ozone is a respiratory irritant,
it does remove bacteria from water. So in theory, the pricey Tersano seemed promising.
Reality was a bit messier--literally. Tersano claims its filter lasts for “approximately 365 gallons,” but the four units we tested performed inconsistently. One clogged after 126 gallons and also leaked, a potential shock hazard since the Tersano must be plugged in to work. A second unit stopped automatically dispensing water after just 43 gallons. Manually dispensing water was inconvenient and spritzed water onto the counter.
The Tersano sterilizes water with ozone, but the sterilized water must pass through a charcoal filter before it’s dispensed. And dissolved organics, such as proteins in your pipes, aren’t removed by ozone. As with other water filters, the Tersano’s filter chamber isn’t airtight, so bacteria in the air can grow on those dissolved organics as they accumulate over time, contaminating both the charcoal filter and any water that passes through it. Tersano cautions users to throw out filters if the unit hasn’t been used “for a long period of time.”
We also found that the Tersano’s ozone didn’t always stay harmlessly in the water. Though three units emitted only trace amounts, we detected elevated levels in the air coming from the fourth sample as it bubbled away during four separate tests. One ozone reading we took at 8 feet from that unit was nearly five times the close-range limit of 50 ppb that air-cleaner manufacturers voluntarily follow. Ozone can dissipate quickly, but exposure at this elevated level could cause severe irritation, especially to asthmatics.
The bottom line. When it worked, the Tersano removed lead, chloroform, and bad taste well. But because of the problems we encountered during testing, we suggest you avoid it.
Reality was a bit messier--literally. Tersano claims its filter lasts for “approximately 365 gallons,” but the four units we tested performed inconsistently. One clogged after 126 gallons and also leaked, a potential shock hazard since the Tersano must be plugged in to work. A second unit stopped automatically dispensing water after just 43 gallons. Manually dispensing water was inconvenient and spritzed water onto the counter.
The Tersano sterilizes water with ozone, but the sterilized water must pass through a charcoal filter before it’s dispensed. And dissolved organics, such as proteins in your pipes, aren’t removed by ozone. As with other water filters, the Tersano’s filter chamber isn’t airtight, so bacteria in the air can grow on those dissolved organics as they accumulate over time, contaminating both the charcoal filter and any water that passes through it. Tersano cautions users to throw out filters if the unit hasn’t been used “for a long period of time.”
We also found that the Tersano’s ozone didn’t always stay harmlessly in the water. Though three units emitted only trace amounts, we detected elevated levels in the air coming from the fourth sample as it bubbled away during four separate tests. One ozone reading we took at 8 feet from that unit was nearly five times the close-range limit of 50 ppb that air-cleaner manufacturers voluntarily follow. Ozone can dissipate quickly, but exposure at this elevated level could cause severe irritation, especially to asthmatics.
The bottom line. When it worked, the Tersano removed lead, chloroform, and bad taste well. But because of the problems we encountered during testing, we suggest you avoid it.
