# Why does day old urine smell rank while fresh unine does not?
**URL:** https://boards.straightdope.com/t/why-does-day-old-urine-smell-rank-while-fresh-unine-does-not/457224
**Category:** Factual Questions
**Created:** [July 21, 2008, 3:44am UTC](https://boards.straightdope.com/t/why-does-day-old-urine-smell-rank-while-fresh-unine-does-not/457224 "2008-07-21T03:44:14Z")
**Posts on this page:** 3
**Page:** 1
### Author:  [@astro](https://boards.straightdope.com/u/astro)
#### Post date: [July 21, 2008, 3:44am UTC](https://boards.straightdope.com/t/why-does-day-old-urine-smell-rank-while-fresh-unine-does-not/457224/1 "2008-07-21T03:44:14Z")
In scenarios where the toilet is clogged or simply remains unflushed, urine that sits in the bowl the better part of the day smells pretty rank after awhile, but fresh urine often has relatively little smell. What is going on that causes it to stink if it sits over time?
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### Author:  [@Nunavut\_Boy](https://boards.straightdope.com/u/Nunavut_Boy)
#### Post date: [July 21, 2008, 3:46am UTC](https://boards.straightdope.com/t/why-does-day-old-urine-smell-rank-while-fresh-unine-does-not/457224/2 "2008-07-21T03:46:44Z")
Bacteria converting the urea to ammonia and other nitrogenous breakdown products. (IIRC)
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### Author:  [@WarmNPrickly](https://boards.straightdope.com/u/WarmNPrickly)
#### Post date: [July 21, 2008, 3:48am UTC](https://boards.straightdope.com/t/why-does-day-old-urine-smell-rank-while-fresh-unine-does-not/457224/3 "2008-07-21T03:48:36Z")
Beat me to it. Fresh urine is usualy sterile. Old urine is not.