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I remember a former president flying his 747 jets across the ocean and back to attend a one-day conference on how to reduce carbon emissions. His jets probably used more gas than my wife, kids and I will use in our lifetime. When he came back, he told us we (all Americans) should give up our Las Vegas vacations to reduce emissions.

I was reminded of this, on a much smaller scale of course, on a recent home inspection. There was a brochure on the counter touting all the water-saving features: low-water toilets, low-water showerheads, low-water motion-sensing sink faucets, etc.

Now I’m not a tree hugger, but I know water is a valuable resource in our state, so this made me happy. I try to do my part to save water. I only wash my car in August and only shower on Saturdays.

But back to the water-saving home. I opened the cabinet under the kitchen sink and found a Reverse Osmosis (RO) filter system. This type of filter uses water pressure to force water through a membrane, and has a line that connects to a drain pipe under the sink. For every gallon of water it produces, an RO filter pumps 3 to 4 gallons down the drain. So I figured the RO filter just offset all the water-saving faucets and toilets.

Our past president could not see the hypocrisy in flying his huge jet over the ocean to meet with people to figure out how to use less gas. This did not surprise me — I expect hypocrisy in all politicians. They never seem to understand they’re spending OUR money. But I digress again.

I believe that most people with RO filters honestly do not realize how much water they’re wasting. Twenty years ago I bought an under-the-sink filter for my own home. I was actually going to buy an RO filter, until I did a little research. I found the following information in the FAQ in a brochure (that was trying to sell RO filters):

“All RO systems produce waste water. About 4 gallons wasted per 1 gallon purified (4:1) if you are on a municipal water supply with good pressure (75 degree water at 60 psi). Below 40 psi RO filters do not work and only produce waste water. An RO system takes a long time to filter water, so it requires a storage tank. If you fill up a gallon jug, the filter may be ‘running’ for 60 to 90 minutes to refill the tank.”

In other words, an RO filter does not just waste water when you have the faucet open. Under high use, an RO filter could be running more often than not trying to keep that tank full. And this is under optimal conditions. If your water temperature or pressure is lower, your water is hard, or the required pre-filter is dirty, the RO filter will take even longer to filter water.

I bought a top-of-the-line charcoal/canister filter. It doesn’t filter quite as well as an RO filter. But I figure with all the things I do that are dangerous or bad for me, I will probably die from French Fry Fibroses or Red Meat Rheumatism before the water can get to me.

I bring a gallon of water to work each day in the summer, and we use the filtered water for drinking, ice, coffee, lemonade, iced tea, cooking, pet water, etc. I figured we use around 5 gallons a day, so with an RO we would be pumping up to 20 gallons a day into the drain. That’s up to 600 gallons a month or 7,200 gallons a year. That’s a lot of water.

I have inspected some new energy-efficient homes that route the discharge water from an RO filter into the water heater, avoiding “wasting” water. However, 99 percent of the RO filters I see drain the water into the drain pipe under the sink, and out to the septic tank or sewer.

Randy West owns Professional Building Consultants in Prescott. He is state-certified and has performed more than 7,000 home inspections in the Prescott area. West serves on the Home Inspector Rules and Standards Committee for the Arizona Board of Technical Registration. Contact him at or visit