How Reverse Osmosis Works

Smaller-scale Applications of Reverse Osmosis

At some retail stores, you can buy jugs of reverse osmosis-treated water from vending machines.
At some retail stores, you can buy jugs of reverse osmosis-treated water from vending machines.
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Maybe you've decided that you'd like to get your hands on some delicious reverse osmosis water. Why don't you just pour some water into a reverse osmosis pitcher and enjoy a long, cool drink?

Well, it's not quite that simple. Because reverse osmosis requires a certain amount of pressure, you won't find a reverse osmosis filter pitcher. And if you do want reverse osmosis water running through your entire house, you are essentially committing to buying an entirely new water system. But if you just want reverse osmosis water for drinking or cooking, that doesn't mean you've committed to converting your basement to a mini-industrial reverse osmosis plant.

Your first smaller-scale option is an "under the counter" system. A reverse osmosis system is connected to the water supply under your sink, where the water passes through three to five filters to achieve purity. The filtered water is then stored in a storage tank (also under the sink). An entirely separate faucet is then installed on your sink, fed from the storage tank below. Expect to pay an average of $200-500 for a system like this. And remember that you're probably doing the installation yourself, so you might want to be fairly confident in your fix-it skills.

Maybe you're little nervous about installing an entire faucet and water system (or perhaps nervous that your landlord might not be thrilled with your DIY resourcefulness). Renters and not-so-handy folks, rejoice. There are also reverse osmosis countertop filters, which allow you to hook up a small filtration system directly from your sink. Simply attach the "feed" line to the faucet, turn the faucet on, and the water is filtered through a small system that's small enough to cram next to the microwave. The purified water line can then be placed in a pitcher for easy, accessible purified water.

But they might not be ideal for everyone; keep in mind that the countertop systems can be quite slow due to lower-flow water faucets, and they'll cost around $150 at least -- not to mention the cost of changing the filters (about $30) every few months.

Let's shoot through to the next page to see some more of the drawbacks of reverse osmosis.