i'm not sure if this is the best place to ask this question, if not please let me know a better place. I just purchased a very cheap 300 gallon water tank. It was cheap due to the fact that they stored Canola oil in it, and didn't clean it. They recommended a de-greaser along with a high powered water sprayer. Before I try it, I wanted to see if anyone had any advice on cleaning it, if a de-greaser is the best route, how much I need to use, or any other advice.

Also, my mom said if I don't get all the Canola oil out, it never spoils and it wouldn't kill us to drink if there was a disaster and we HAD to drink it to survive. Is this true? Thanks in advance.

Edit: We will be storing water in it as emergency water, and it is plastic, i'll attach a picture.

enter image description here

  • Fats generally spoil by going rancid (which tastes nasty, but won't kill you, AIUI). Commented Mar 28, 2017 at 2:24
  • How about a match.....and it would be sterilized.?!
    – Lee Sam
    Commented Mar 28, 2017 at 4:16
  • Call a local pool vendor, they'll have steam wand or power washer for cleaning filter heads in the off season. Odds are good they'll do it for a couple of bucks. Commented Mar 28, 2017 at 4:54
  • 1
    Since you plan on using this to store water for a long term you will want to make especially sure that the type of plastic is a BPA free type. There are also other types of plastic that can leach harmful chemicals into the stored water so investigate and try to avoid those. Next investigate if this plastic is UV light resistant. If stored outside in the sunlight many types of plastic will degrade over time due to UV exposure. Lastly be aware that water stored for a long time can grow green crud in it if exposed to light and the water was not properly filtered or treated.
    – Michael Karas
    Commented Mar 28, 2017 at 10:24
  • I love the jaunty angle of the horizon and the friendly thumbs-up included at the bottom of the photo. On a more serious note, you might need to add something to the water to keep it potable if it is not going to be regularly replaced. Commented Mar 28, 2017 at 11:03

2 Answers 2


Hot water (how hot would depend on the type of plastic - at least warm, to start with) and baking soda (bicarbonate of soda.) Let stand (or agitate, if you want) for 24-48 hours, repeat as needed.

If you can source food-grade lye and are aware of and able to take appropriate precautions for handling it, it would work a bit faster, but in both cases you are using an alkali (mild or strong) and that will saponify (turn to soap) the residual oil. Baking soda is cheap, safe to handle, and easy to get as a food-grade item.


If it was me, I'd empty the tank completely, then fill with hot water and dawn dishwashing liquid, then rinse and repeat.

If the tank is steel, you will have rust issues. Get a flashlight and look inside for peeling paint, and rust.

What are you going to store in the tank?

If it is fuel, I would say don't do the water, just fully drain and then add fuel.

  • If it's diesel fuel, you don't even need to drain it fully. Diesel used to be slick, but now it's dry like gasoline now that they removed the sulfur. The poor lubricity wears older injection pumps. A little canola oil will return a lot of that lubricity. Commented Mar 28, 2017 at 3:29
  • It is water.. and it is completely empty right now. It is plastic - see update! Thanks
    – ruevaughn
    Commented Mar 28, 2017 at 4:36

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