After the power went out following the December 15th windstorm, I used my gas-powered generator keep my refrigerators and furnace running.

The power came back on four and half days later, so we were luckier than some, but in the process I ran through a few containers of gasoline.

Because another wind event was forecast, I figured it would be prudent to top off my gas cans in case the power goes out again.

At the gas station, I filled my four, five gallon plastic containers, along with a single, one gallon jug and was surprised to see the gas meter stop at 22.1 gallons.

I looked at the jugs to see where I had filled them to and saw that all were below the fill line, the way I always fill gas cans.

Four, five gallon containers and a single one gallon container, if topped off should come to 21 gallons, exactly, shouldn't it?

Even though my gas cans were all below their capacity, according to the pump's meter, I had just pumped an extra gallon plus.

I thought about going into the gas station to tell the attendant, but opted instead to take some photos of the cans, the meter and my receipt, because the attendant would not likely just give me money out of his till to make up the difference based on my complaint, and I was pretty sure that this is a mechanical issue that would have to addressed by some authority.

While I don't like being taken advantage of by a machine, there's not much I can do about it myself. While I drove home, I pondered the discrepancy.

On the gas pumps, there are little green sticker tags, put there by the Department of Agriculture's Weights and Measures Program, and I've seen them testing at this particular station before.

A guy in an official looking truck filling some precisely calibrated stainless steel gas cans. On the pump I was using, the punch out on the tag indicated that it had last been tested in 2004.

A single gallon of overcharge may not seem like much in the course of a fill up, but with rough calculations, a low estimate of 25 motorists per day at this pump multiplied by a gallon per fill up comes to 25 gallons a day. 25 gallons a day at $2.56 a pop is $65 dollars a day profit. Just from one pump. A weeks worth of this comes to $455 bucks. You can compute what this figure comes to over the course of months or years.

At home I went online and found the Weights and Measures website and called the phone number to see what I could learn about the parameters of the issue.

I got an answering machine that directed me to leave a detailed message with the gas station in question, the pump number and the grade of fuel involved. Back at the Weights and Measures website, I found a news release.

"In 2004, the agency's nine inspectors tested more than one-third of the gasoline pumps in the state. On average they found problems with about 12 percent of the 22,000 meters tested. About 60 percent of the problems were for improper measurements. The remaining problems were mechanical in nature such as leaking hoses or malfunctioning displays."

To pass, the pumps must deliver within 0.5 percent of the quantity tested. For example, on a 10-gallon purchase, the total must be within 6.4 fluid ounces of the amount delivered - that's slightly more than half the amount in a regular can of soda.

"Our inspectors test thousands of meters at gas stations and check the quality of fuel on an unannounced basis in an effort to protect consumers at the pump," said Jerry Buendel, manager of the Washington State Department of Agriculture's (WSDA) Weights and Measures Program.

When inspectors find a gas pump that is shorting the customer, they order the device out of service and require that the station have the device repaired before using that meter again.

My own experience is not based on precise measurements. My estimate of a gallon of overcharge, mitigated by the WSDA's allowance of about a half of a soda can of leeway makes the issue seem less important.

I won't mention the name of the station, but I did leave the information with Weights and Measures and asked them to check this out.

If you think you're being overcharged for what you're getting at the pump, you can reach the Department of Agriculture's Weights and Measures Program at 360-902-1857.