I recently asked a friend how I should recycle my used deep frying oil because I just don't have enough oil to justify taking my car, drive 20 minutes away to the waste collection site for few liters of oil.

So my friend advised me to just throw it within the garbage. The oil has to be burn anyway so it will be burned at the recycle station and generate electricity and heat from it.

One other solution, is to simply throw the oil in the sink. When it reaches the wastewater treatment plant, settling basins will separate the solid, the liquid and the floating oil.

So I propose here three solutions, and I would like to know which one is the most adapted for someone that want to eliminate about 5 liters used cooking oil per year.

  1. Store it in the basement then go to the waste collection site located 20 minutes away by car and get rid of the oil once a Year.

  2. Save that storing space by throwing 1 liter within the regular garbage 5 times a year in a sealed container.

  3. Throw the used oil in the toilet and throw away the shrank empty plastic container in the prepaid garbage bags (I have to pay 3$ per 35l bag).

These propositions have to come with goals:

  1. Most energetically viable solution
  2. Less environment impact
  3. Most convenient solution
  • 3
    $\begingroup$ Option 4 might be to contact a local biofuel organization or enthusiast who would pick it up and convert it into biodiesel for their own use... Saves you effort as well as being environmentally friendlier. $\endgroup$
    – BobT
    Commented Feb 11, 2017 at 14:23
  • 2
    $\begingroup$ Disposing of oil down the sink or via the toilet is a bad idea. It can lead to blockages of sewer pipes - research fatbergs. By doing this you are forcing your problem onto someone else - highly irresponsible. One other solution is to stop deep frying food! $\endgroup$
    – Fred
    Commented Feb 12, 2017 at 3:00
  • $\begingroup$ What do you intend "energetically viable" and "environment impact" to mean, specifically? Where do you live - are there regulatory concerns? Why are you asking us, rather than your local waste disposal experts, about the consequences of flushing oil on their systems? Do you have an engineering question and, if so, can you properly express and constrain that question so that it will attract useful answers? This is principally a technical site. $\endgroup$
    – Air
    Commented Feb 13, 2017 at 19:49
  • $\begingroup$ Try referring this question to sustainability.stackexchange.com . They may give you some creative tips! $\endgroup$ Commented Feb 14, 2017 at 1:13

2 Answers 2


Option 4: Put it in the container, leave it on your doorstep and offer it for free on craigslist. You will likely find someone that regularly needs it and you can just email/text message them any time you set some out. People use waste vegetable oil to burn for heat, bio-diesel, soap making, animal feed, etc.

Also note that disposing oil down the toilet is very irresponsible. Oil water separation is not so trivial when it is spread across millions of gallons of sewage. Oil also makes the water underneath go aerobic; creating additional smell issues. When in doubt about a type of waste; it should go to the landfill. Remember that the water from your toilet or storm drain has to be processed and cleaned to a level that can enter a river or ocean.


Storage space for a 5-litre liquid shouldn't be that much, I think. So, if it doesn't smell, I'd go for option 1.


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