What’s the best way to remove tannins from water?

Water

What is the best way to remove tannins from water? Do you have to go with those expensive tannin filters?
—Amandio Pereira, via e-mail

Ka-ching! Sorry, but you probably do. Tannins—from decaying organic matter—not only make your water look tea-coloured, but they can stain fixtures and laundry. We’re assuming you’ve already tested your water, and you know tannins are the problem. If you get your water from the lake, “ninety-nine-point-nine per cent of the time, the colour is from tannins,” explains Vikaf Thusoo, a product manager and technical specialist with Envirogard, a company that manufactures water filters and purifiers in Richmond Hill. But tannins aren’t the only culprits: If your water comes from a well, sediment and iron could also cause discoloration. “A water test is always the first step,” says Thusoo.

We’re assuming, as well, that you want to treat all the water coming into the cottage. In that case, you’d best install a whole-house water conditioner that removes tannins. “Basically, it works like a water softener,” explains Larry Miller, the owner of DSMI/Passport Water Purification Products in Thornton, Ont. The unit contains an ion-exchange resin that attracts the negatively charged tannin molecules and pulls them out
of the water. These units cost between $1,200 and $1,800. On the other hand, if you simply want to remove tannins from your drinking water, you may need only a carbon purifier, which goes under the sink and costs about $500 to $600, says Miller.

Once you install a system, test the treated water at least three times per year, says Brenda Armstrong, the acting program manager for safe water with the Simcoe Muskoka District Health Unit. You want to make sure it’s working properly, for one thing, plus “sometimes when you treat one problem, you can cause another.” (Bacteria can get in during the tannin-removal process.)

Before you spend any money, shop around—look for a unit with a warranty of 10 years, suggests Miller. By then, you’ll likely need to replace the resin. Or you may want a new treatment device.

“Probably, in 10 to 15 years, we’ll have better technology,” says Miller. “At least, I hope so.”