Do not pee in your DEF tank, read why here!

We have been hearing over and over a comment about Diesel Exhaust Fluid that is particularly frightening ,

“Diesel Exhaust fluid is the same as ____ urine”           brown_cow_197654

Fill in the blank with any animal you can think of, we have heard it all but most recently , bat and cow urine. We have also heard of people thinking that urinating in their DEF tank will make the engine run. So the common misconception people have about Diesel Exhaust Fluid is that it is made from urine. This is NOT true, and acting upon this idea could cost you thousands of dollars in repairs to your SCR engine. On this blog, some light will be shed on the subject, and we will finally debunk this myth for good.

Those who believe in this myth used deductive reasoning to get to that conclusion , so according to them:

Urine = Urea

Urea+water= Diesel Exhaust Fluid

therefore Urine+ water= Diesel Exhaust Fluid


Urea Urea is an organic chemical compound, or the waste produced by the body after metabolizing protein. But since 1828, German scientist Friedrich Wöhler invented the process to create the synthetic version of urea. In 1870 the process of producing  urea through dehydrating ammonium carbamate under conditions of high heat and pressure was invented. So yes, urea can be obtained from urine, but lets find out why Diesel Exhaust Fluid is not just urine and water.

I will be comparing the material data sheets of  both automotive grade urea vs human urine.

  • According to wikipedia, “Human urine is an aqueous solution of greater than 95% water, with the remaining constituents, in order of decreasing concentration urea 9.3 grams/L, chloride 1.87 grams/L, sodium 1.17 grams/L, potassium 0.750 grams/L, creatinine 0.670 grams/L and other dissolved ions, inorganic and organic compounds.” Read the full description here.
  • Diesel Exhaust Fluid uses automotive grade urea, at 32.5% concentration. This urea contains , 0.3% Biuret maximum, 0.5 % magnesium max , 0.5 % calcium max, 0.5% phosphate max, 0.5% iron max,0.5% potassium maximum.

When comparing the two there are various differences:

  1. Human urine only contains 9.3 grams per liter of urea concentration
  2. Human urine also contains chloride, sodium , potassium , creatinine and other dissolved ions
  3. Human urine is 95% water, which is also full of ions and minerals

The water needed to create Diesel Exhaust Fluid has to be de-ionized and de-mineralized , a process that only a highly specialized filtration machine can achieve.


From all this information we can conclude that even though urine has urea, it is not the correct concentration nor does it have the purity needed. The water that comes from urine is also full of ions and minerals which make it very low quality water.


Diesel Exhaust Fluid is highly concentrated and very pure urea plus de-ionized water .The standards for Diesel Exhaust Fluid are very specific and can be found here

I hope that this blog has been informative, highlighting the differences between urine and Diesel Exhaust Fluid. Please do not urinate in your DEF tank, the SCR system will be damaged and it will cost thousands of dollars to repair.

Here at Transliquid Technologies we specialize in providing the best quality of Diesel Exhaust Fluid.

25 thoughts on “Do not pee in your DEF tank, read why here!

    1. When DEF is injected into the exhaust stream and mixes with harmful NOx,it changes its composition into harmless nitrogen and water, thus greatly reducing the amount of contaminants that are released into the air. Gasoline vehicles do not use DEF because in general diesel engines emit far more nitrogen oxides, which cause smog. Gasoline engines produce different types of contaminants.

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  8. I have been urinating in my rig’ s DEF tank for years now. Runs like a champ and saves me tons of loot!

  9. Nicely explained. Now if only someone could invent a filtration system that uses nothing but electricity and inexpensive filters to crack DEF out of urine, we could solve the problem of piss bottles being left in parking lots and all the health problems many truckers torture themselves with by living on the brink of dehydration …

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  11. That is false. def is a dumb thing and should be discontinued forever. who invented DEF is a complete IDIOT

  12. Well if this bluedef crap is suppose to be helping with the community then why are y’all making us buy the crap only way i see it helping us helping people get rich fast and helping poor people become homeless just saying

  13. I talked to a feller said he had DEF disconnected, said his truck gets lots better milage and has lots more power, said it cost him over 2k to do this, is that possible

  14. Nothing was discussed as to how the DEF deteriorates and why it can’t be used after 2 years. I have seen many demonstrations that show the urea concentration of 32.5% for new DEF. Then they take a date code of 2-3 years old and amazingly it also measures 32.5%. They seem dumbfounded but continue to state that the DEF is old and can not be used. WHY.? If it is deionized water or distilled water and 32.5% DEF, what determines that it is no longer fit to use.? RV users need to be educated. Please leave an answer at my email address

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