If urine is acidic, why does limescale build up in toilets?
In: Biology
Because (1) normal urine is only very mildly acidic, (2) urine doesn’t (directly) hit the parts where limescale builds up and (3) you’re not soaking your toilet in urine.
Normal urine has a pH of around 6. That’s nothing – it wouldn’t even taste sour. For comparison, black coffee has a pH of around 5, and milk is around 6 (with 7 being neutral – the pH of pure water). So you’re not getting real acidic limescale-dissolving power there to begin with.
Then, you’re taking that very weak acid and diluting it in water. So now it’s even less potent. Plus, there are parts of the toilet that your urine never even hits (like under the rim).
And *then*, you’re going to be flushing that very, very weak acid away pretty much straight away, and replacing it with tap water. So any limescale that does come into contact with your weaker-than-milk acid, only does so for a very brief period.
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