I inadvertently put somewhere from a pint to a quart of regular gasoline into the 30 gallon almost full plastic (polyurethane I think) fresh water tank of my C-class motor home. I was saved from putting in more because the full tank kept shutting of the gas pump nozzle. Driving home the fumes even triggered my propane gas alarm!
Discussion of how this happened will not be entered into!
Going to the internet yielded the usual plethora of utterly useless advice, half the posts saying that if the fuel was diesel then there was a serious problem whereas if it was gasoline there was not, the other half saying the exact opposite. Most advised replacing the tank and pump, others the entire system including all piping circuits. Most had a cousin who knew a guy who had once done this and after spending two years trying to get rid of the odor gave up and replaced everything. Others suggested all kinds of cleaning methods, but most saying they had not tried it themselves. One man absolutely knew the answer; fill with red wine and let stand, more than one recommended filling the tank half fill with 180 proof cheap vodka, and topping off with water. Hardly cost effective "solutions". Note the pun.
This is not theory, I used this method this past week to clean the tank in situ, and it works 100%. Any instructions that advise you to use a sequence of different agents, most of which are anti-bacterial and have no effect whatsoever on the hydro-carbons of gasoline, and also advise the gasoline odor will probably remain for a long time, are simply wrong. The solution is simple, and 100% effective, and there is no lingering odor afterwards, nor manifestation of gasoline at all, the freshwater in the tank is as fresh as it has ever been. I contaminated the tank with gasoline, so I donโt know if this will work with diesel, but I believe it will.
Before I explain the process, take into account the following.
(1) Gasoline floats on water, it does not dissolve into the water, nor mix with it.
(2) Gasoline adheres to the inner sides and top of the tank.
The above means that you cannot simply flush by draining the tank out of the bottom, the gasoline will be on the surface of the draining water and simply stick to the sides of the tank. It also means that the gasoline cannot be washed off the sides and top of the tank using only water. To break the bond between the inner surfaces of the tank and the gasoline, and to make it disperse into the water so it can be flushed away, you need a surfactant/dispersant. This allows the gasoline to be pulled off the walls during flushing, and suspends it in the flushing solution so it can be drained away, which is exactly what is required. And it accomplishes this in situ without scrubbing, as long as you ensure good and sustained contact of the surfactant/dispersant containing solution with all inside surfaces of the contaminated tank and piping, and that you perform the water flushes in the understanding that any petroleum contaminates not fully dispersed will be on the surface of the solution, and therefore the initial phase of every flushing must be to force the water out the top of the tank.
This surfactant/dispersant is present, and is the key ingredient, in โDawn Ultraโ dishwashing liquid, the one marked โNot for Use in Dishwashersโ. All dishwashing liquids designed for use by hand contain a surfactant/dispersant developed not to attack and irritate skin, but there are reasons Dawn is the liquid of choice for cleaning up wildlife after oil spills. This dishwashing liquid is all you need, any additional cleaning or sterilizing agents such as Bicarbonate of Soda or Vinegar or bleach will at best do nothing for you, and at worst negate the effect of the Dawn. For all I know things like borax may not only do nothing other than possibly negate the Dawn; they may also be a serious danger to oneโs health. Use only dishwashing liquid, note Dawn does have a petroleum based oil based surfactant/dispersant, and thus complies with the commonly held theory that it is necessary to use an oil based surfactant/dispersant to remove oil based contaminates.
Follow the steps below exactly, donโt skip any, I explain why they are necessary. They accomplish all the parameters I explained above as being essential to a successful result.
Here is how I fixed it;
(1) Pulled the fuse on the freshwater pump so I could not accidentally pump the contaminated water into the system. But even if you do, this correctable.
(2) Drained the tank through itโs drain petcock (please dispose of the contaminated water properly), refilled it, and drained it again. I had accomplished nothing, it reeked of gasoline and there was a gasoline sheen on any water I took out of it. But at this point I had an empty tank with the inner sides and top coated with gasoline, and filled with gasoline fumes.
(3) I filled the tank quarter full, put in a 24 oz bottle of Dawn (use a fragranced one, my preference is orange, so you can tell by the lack of fragrance when your system is cleared of the Dawn,) and then filled the tank. As the vent tube enters horizontally into the side of the tank at the top, as does the filler tube, this does not allow it to fill to the top, so I then drove about a half mile, rocking the RV with the accelerator and brake so the solution got sloshed onto the top and all the sides. It is not necessary to agitate, nor foam, just to make sure the liquid coats all inside surfaces. Also clean the filler tube with a bottle-brush soaked in Dawn solution. Turn some tight corners as you drive so centrifugal force sends the Dawn solution up the vent pipe and the filler tube. Leave overnight. If you can park your RV with the wheels on the filler side up on a curb, or embankment, this will allow the tank to be overfilled till the solution runs out the filler, and then it will be in constant contact with the roof of the tank.
(4) Next morning, drain as follows in step (5). THIS IS CRITICAL AND THE REASON IT ALL WORKED. Use this method every time you drain the tank, to float off any gasoline which is lying on top of whatever is in the tank, rather than let it stick to the sides as the tank drains.
(5) Put a hosepipe, without any fittings on the end, right down through the filler pipe and to the bottom of the tank. Make sure you have your city water pressure reducer on the tap, in order not to overpressure the tank, and a external filter on the hose if you use one, which you should. Then with the tank drain petcock closed, turn on the hosepipe. The tank will start to fill from the bottom and push the contents out through the filler pipe. When the water is running out clean and not foaming, shut the hose off and open the drain petcock and allow the tank to drain fully. If you are letting it fall onto your driveway you will see the oily sheen from the gasoline that has been expelled through the filler.
(6) Fill the tank with water through the hose going to itโs bottom, and smell the air coming out the filler cap as the tank fills. It will still smell of gasoline, but hopefully not as strongly as before. It will also smell of orange fragrance. When the tank is full let the water flood out of the inlet for a number of gallons, till it is running clear.
Remove hose, close cap, and do the up and down the street rock and roll drive. Put the hose back in the filler down to the bottom, turn on, and let water run from the filler. Then shut off hose, remove, and drain tank through its petcock.
(7) Repeat (3) through (6) including leaving Dawn solution overnight. This time the smell at the filler tube will only have a faint smell of gas, and mostly be orange fragrance.
(8) Repeat (3) through (6) again, including leaving Dawn solution overnight, but this time with hot water, both for the Dawn solution and the subsequent flush. You can turn your home water heater on high, and connect your filler hose to your kitchen faucet with the proper fitting. At this point there should be no gasoline smell in the air coming out the filler as the tank fills, but just orange fragrance. Also when flushing out the Dawn solution which was put in hot, do the following before starting to flush and/or drain. Do not do it for the earlier flushes. It is to take care of any contamination in the feed line to the pump from the tank, and in the pump impeller itself.
(9) Hook up your hose to your city water connection, and shut off the connection from the freshwater tank to the system. Mine has no petcock, it is a one-way flow valve from the tank to the system, city water is stopped from going to the tank by this valve. Shut the valves to the hotwater tank and open the hot water tank bypass valve. Turn on each tap in turn, so they run strongly, and then shut each tap off. Flush the head so it runs strongly. Remove the city water hose, the system is now filled and pressurized. Close the bypass line for the hot water tank, so the hot water circuit is now dead-headed.
(10) Now, do the following before you drain the Dawn solution put in hot, and for every subsequent drain hereafter. Replace the freshwater pump fuse. Switch on the pump. It will not run because the system is pressurized. Open the drain petcock on the system hot water line. The pump will immediately start up and pump the solution through the pump, down the hot water line, and out the drain. Let it run for about 30 seconds, this will take care of any contamination in the feed line to the pump from the tank, and in the pump impeller itself. Catch some water coming out of the drain in a glass, it should be very foamy, smell of orange fragrance, but no gasoline smell.
(11) When flushing with hot water, the next step, following all the exact flushing procedure as before, including the hose into the tank and the rock and roll drive, catch the water from the hot water line drain again. It should be less foamy and less orange fragrance smell, and no gasoline smell whatsoever.
(12) Finally flush with cold water, all the usual steps, the water you catch now should be perfect, no smells and no taste.
(13) Because of all the hoses that have been pushed into the tank etc. itโs a good idea to sanitize the tank before filling with drinking water. This is not to remove gasoline or Dawn residue, that should all be gone by now. It is simply to sterilize the tank. I use a half-cup of household bleach in my 30 gallon tank. Fill according to instructions, let run through pump by opening hot line drain for 30 seconds, let sit four hours, drain directly out of the tank drain, no need to flush out the filler with the deep entry hose. Fill and flush tank with plain water, including running through the pump for thirty seconds using the hot water drain petcock, and then fill with drinking water treating it as you normally would. I put in a teaspoonful of bleach and a cap-full of RV water freshener solution.
None of the above is conjecture nor theory, it worked 100%, cost next to nothing, and just took a little time.
