Taking the piss.

In a bout of over-reaction that the Daily Mail would be proud of, Portland Water Bureau have dumped almost 8 million gallons of water after a man urinated in an open reservoir.

Now, aside from the patently ridiculous reaction in the first place (do they do the same if animals defecate near  the water?), I thought it might be instructive to look at what this criminal waste of fresh water has achieved.  So – let’s have a look at what these dilution ratios actually mean.

For the sake of simplicity, I’m going to convert quantities into metric.  Now, urine volumes vary wildly, but lets assume he was taking a massive drunken piss of about 1000 ml (1 L).  7.8 million gallons of lake converts to 29,500,000 L.

So we have a dilution ratio of 29,500,000:1

Now that’s a pretty massive dilution.  And actually, urine is over 95% water anyway.  So what else is in urine? Well, fortunately, NASA very kindly did some work on this. Basically, we’re looking at:

Those are the total quantities dumped into the lake.  Now dilute those amounts by the ratio calculated above to get an idea for how much there is in 1 L of lake water:

In which case we’re looking at fairly miniscule amounts.  But as the chemists among you will realise, grams are fairly meaningless.  Really we want to know what that is in mols.  In other words, mass tells us nothing about how many molecules of each thing there are present: if a creatinine particle weighs 0.000,000,027 g then there’s only one of them in the lake, which makes it remarkably unimportant.  So how many mols of each of those chemicals are present?

So Urea is present at levels of 5 parts per billion. Incidentally, if arsenic were present in the same concentration as urea, it would still be 10x below the permissable limits for drinking water.

Still, on the bright side we’re still a few orders of magnitude away from homeopathic dilutions so no-one needs to worry about some powerful  lake of uber-piss being formed.

By the way.  Urine is basically sterile.


About Pete Rowley

Earth Scientist with a background in volcanology and sedimentology. Enjoys a good rant, beer, and games. Dislikes reality TV, crowds, and unreasonable people.
This entry was posted in General, Geology, Media & Perception, Science and tagged , , , , , . Bookmark the permalink.

One Response to Taking the piss.

  1. Roundy says:

    apparently they do not process the water one it’s way out of the reservoir to the tap. but still, a slight over reaction.

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