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A suprisingly useful aqueous mixture of several compounds.


Production of urine is a natural process for most animals.


  • On its own, urine has a NPK rating of 0.6, 0.04 0.08[1]
  • 85% phosphoric acid is 15.2 molar, so between 500L and 1200L (130-320 gal) of urine would be required to make 1L of that acid.
  • 25% ammonia (maximum non-lossy concentration) is 13.4 molar, so about 10L of urine would be required to make 1L of that solution.
    CO(NH2)2 + H2O 2 NH3 + CO2 // 1M urea becomes 2M ammonia
    10L (2 ammonia (0.66M urea)) = 13.4M ammonia, to be dissolved in 1L of water.


The major products of interest derived from human urine are[2]:

Other animals' urine may also include:

Maximizing urea content

In the ammonia production from urine process, it is of value to maximize the urea content of urine. Simple ways to do this include:

  1. Collect urine first thing in the morning - urea is produced during the night, but is not diluted by additional water (not) consumed while you sleep.
  2. Collect urine within 36 hours of heavy exercise
  3. Collect urine from humans eating large amounts of protein rather than carbohydrates.

Obviously all of these could be done simultaneously, given the right diet, exercise, and sleeping schedule.


Urine contains a variety of useful compounds, and to extract most of them it is necessary to remove a substantial amount of the water from the urine. Unfortunately, urine with a low water content has a foul, penetrating and persistant odor. This means that the traditional method of reducing/drying urine (boiling) produces quite a stench.

Alternatively, place a beaker of urine in a closed container, surrounded by calcium oxide powder, close the container, and heat it to 90°C for several hours. The water vapor rises out of the beaker and is immediately trapped in the calcium oxide, leaving any volatile organics in the container, hopefully to redeposit in the beaker. This is a slow process, depending on the temperature. It can take hours to reduce the contents of the beaker by 100ml.[3] It does, however limit the smell.

See Also


  1. Senecal, Jenna; Vinnerås, Björn (2017) "Urea stabilisation and concentration for urine-diverting dry toilets: Urine dehydration in ash"
    Science of The Total Environment 586; pp650-657. Elsevier
    link courtesy researchgate.
  2. Putnam, David F. (1971) "Composition and Concentrative Properties of Human Urine" (local copy)
    link courtesy NASA.
  3. In a recent 93°C run, more than six hours were required to reduce 300ml to 75ml.