In "Wrong Turn" (Ask Sail, April 2006) Nigel Calder challenged readers to come up with ways to get gasoline out of a water tank. Here are some of the solutions that you came up with:

I too have poured gasoline in my water tank—after cautioning everyone before me not to do it. I solved the problem by putting a generous amount of liquid dish detergent (I used 1/2 bottle) into the tank, then filling it with salt water. I then sailed around—with several tacks—for about an hour, drained the tank into the bilge, and then did it all over again. It took about four tries to pass the taste test.

I don't know the environmental merits of this, but it does work.
—John Treanor, Houston, Texas

I am the captain of an offshore tug. We had a crack form in one of our fuel tank/potable water tank bulkheads, which contaminated 5,000 gallons of water and all the lines throughout the boat, including the hot water tank. What a mess. The shipyard solved the problem by draining the tanks, refilling them, and adding liquid automatic dishwasher detergent (not dish soap, it suds). One of the exterior garden hoses was attached to the freshwater fill pipe the pump was turned on and re-circulated for a few hours(with all hot and cold faucets running). This was repeated three times and at the end we refilled the tanks with the proper ratio of chlorine per gallon and added a potable water tank product that I think was called Everclear. We had the best tasting water I have ever had on a tug. I hope this helps!
—R. Scott Moorhead, Tarpon Springs, Florida

I accidentally put diesel in my Tayana 42's water tank two years ago. We have two 75-gallon, stainless steel tanks. I put about 2 gallons of diesel and a big slug of biocide and stabilizer in the almost full water tank.

After almost throwing up when I realized what I'd done, the first thing I did was to isolate the tank from the freshwater system and keep the boat still. If the fuel gets into the vinyl tubing, it will be ruined. I then opened up the inspection port on top of the tank and laid oil-absorbing mats on top of the water covering the whole surface. I left them sitting there for 2 weeks, then changed them and left the new ones another 2 weeks.

I then used Dawn dishwashing detergent, just enough to emulsify the oil but not generate suds. I pumped out the tank through the inspection port. I repeated this three times. The last time, I scrubbed every surface of the tank I could get to. I then rinsed it three times with a hose spraying down all the surfaces.

I could not smell any diesel, so I filled the tank and let it sit for a week. Then I took a sample through the inspection port. It smelled and tasted okay, so I opened the tank to the fresh water system. I thought about having the water tested, but figured that if I couldn't smell anything, it was probably safe to drink.

I believe the key was getting as much oil as possible off the surface of the water first, rather than trying to emulsify it. Also, our tank construction helped. Having a big port on top of the tank to work through made it easier. Also, if the water tank is non-crosslinked polyethylene, it will absorb diesel fuel and you won't be able to get it clean.
—Frank Timmons, Deltaville, Virginia

This is a remedy for a dog that has been sprayed by a skunk, it might work for a water tank as well. Mix one 8-ounce bottle of hydrogen peroxide, 2- tablespoons of baking soda, a quarter cup of dish soap and one gallon of water. Wash your tank out with this and then rinse it. You may have to flush it a few times and may want to finish with bleach and water.
—Paul Kodanko, via E-mail

Use Star brite Aqua Clean following the directions on the container. This product contains non-toxic cleaners and emulsifiers that will remove all traces of the diesel fuel and any other contaminants from fresh water tanks.
— Jeff Tieger, Fort Lauderdale, Florida

Dawn dishwashing liquid may help. After draining and rinsing the tanks, pour coffee into the tanks and let it sit for a couple hours. For some reason coffee has the ability to remove many odors and tastes.
—John Stein, Mansfield, Ohio

I was working on a customer's new Catalina 320, and I was in a hurry. The deck fills are next to each other, and I accidentally filled the wrong tank. One of our local curmudgeons said to flush it with Vodka, "the cheaper the better". I poured in a gallon of rot gut, sloshed it around, let it sit overnight, pumped it out, and repeated. None of my coworkers could tell that there was anything but water in the tank and the fussy customer never mentioned it.
—David Disbennett, Toledo, Ohio

From a friend's experience, flushing the tank with lots of vodka was the only thing that worked. I suspect they didn't care about the taste after that, either.
—Susan Ryan, Denver, Colorado

Nigel Calder's Final Word

Thanks to a considerable amount of feedback from readers, it looks like I have the answer. It's cheap Vodka, and lots of it!

The key, as a chemist pointed out to me, is to find a solvent that is compatible with both diesel and water. His choice is anhydrous (i.e. a 100% solution with no water added) isopropyl alcohol (rubbing alcohol, although in this form it generally has water added). It can be bought at an industrial solvent shop. If anhydrous cannot be found, get the highest concentration possible, and not less than 70%, should be used.

After the tank has been drained it should be flushed with the alcohol to remove any pooled diesel at the bottom of the tank. It would be best to isolate any pumps and valves when doing this—the concentrated alcohol may cause rubber parts to swell. Next, partially fill the tank with water, add alcohol, and fill it all the way to the top to flush the sides and top of the tank. The alcohol/diesel solution pumped from the tank should be recovered and disposed of properly.

Vodka is approximately 40% ethanol, which is chemically close to isopropyl alcohol. My chemist tells me it is not as effective a solvent for diesel as isopropyl alcohol, but another reader assures me it works, but requires "lots". In any case, with enough Vodka in the tank, who is going to care about any remaining diesel?