Things You'll Need:
- Tri Sodium Phosphate (TSP)
- Water hose
- Air blower like exhaust from a vacuum cleaner.
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Step 1
Drain the tank of all previous fluids be it gasoline or diesel fuel or fuel oil. Clean out all sludge, water or other liquids or solids such as mud dirt etc. Turn the tank upside down if possible to assist draining completely. Diesel fuel, oil and the like can be disposed of by taking it to an automotive lube business. Cap off all drains to get ready for the next step.
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Step 2
Open the cap at the main filler opening. Fill the tank with good water (cold water is OK) to which has been added TSP at a ratio of 1 cup TSP powder to 5 gal of water. The TSP can be added at any time no matter whether the tank is full of water or empty, makes no difference.
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Step 3
Once the tank is full of the water/TSP solution the mixture needs to be agitated somehow. Best way is to put an air hose down to the bottom of the tank and bubble air slowly over night. If this is not possible fashion a stir stick and mount it in an electric drill and give it a good stir every hour or so. In any event stir it any way you can, but stir it.
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Step 4
The agitation time depends on the method of agitation. Using an air bubbling agitation will require 12 hours or overnight. A less effective method of agitation might possibly take longer up to several days. TSP is a powerful degreaser and the Phosphate Free kind will be OK to just run it down the drain or let it soak into the ground. It will not kill plants.
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Step 5
Once the solution has been drained, the tank needs to be dried out if it is to be used again to store fuel. Best way to do this is to add a gallon or so of denatured alcohol and slosh it around to try and get it all over the inside of the surface of the tank. This will absorb any remaining water. Then drain the alcohol. Blowing some air into the tank will help dry it further.
