Agua Non Potable

September 29, 2005 7:55 AM

Many lavatories on trains have signs warning that the water in the sink is not safe to drink. If it's not clean enough to drink, am I really making my hands cleaner by washing with it?
posted by yankeefog to health (15 comments total)

It is if you've got poop on your hand.
posted by horsewithnoname at 7:59 AM on September 29, 2005

I'm pretty sure it's because they used lead piping, which would cause perfectly clean water to be poisonous but would not effects its cleaning ability that much. I wouldn't take a bath in the stuff though.
posted by cyphill at 7:59 AM on September 29, 2005

Soap is not safe to eat; do you therefore conclude you shouldn't wash with it either?
posted by DevilsAdvocate at 8:06 AM on September 29, 2005

on an airplane i saw readouts for "black water", "grey water", and "clean water"

i made the following assumptions:

clean water - brand new water out of storage. may be potable.
black water - contaminated water
gray water - recycled, like they use on the lawns here in tampa. it's been filtered to get particular matter out and most bacteria, but it's still not safe to drink because of chemicals and some small bacteria.

so on the trains it's probably recycled.
posted by taumeson at 8:07 AM on September 29, 2005

It's because the tank that the water is kept in may contain microbes. Those microbes may make you sick, but they aren't as bad as the ones on your poopy hands or on the hand rail you touched or your shoe laces that you just tied, etc. The train people don't want to be liable if you decide to risk drinking the water, so they put up a warning.

The soap you use will also help to lift them and the particles they hang out on off of your hands.

Unless water is REALLY dirty or contaminated, washing your hands in it is always better than not.
posted by Pollomacho at 8:08 AM on September 29, 2005

gray water - recycled, like they use on the lawns here in tampa. it's been filtered to get particular matter out and most bacteria, but it's still not safe to drink because of chemicals and some small bacteria.

Nope. Grey Water.

Black water probably has human waste in it. Grey water is water that has been used for dishes, shower, sink, washing, laundry -- it normally has some detergent in it and possibly particulate food matter as well. Clean water is just what it sounds like.
posted by anastasiav at 8:14 AM on September 29, 2005

clean water - brand new water out of storage. may be potable.
black water - contaminated water
gray water - recycled, like they use on the lawns here in tampa. it's been filtered to get particular matter out and most bacteria, but it's still not safe to drink because of chemicals and some small bacteria.

Obviously you've never owned a Winnebago. ;)

Anastasiav has the correct definittions.
posted by spicynuts at 8:17 AM on September 29, 2005

Incidentally, a teenager in the US saw water being loaded into planes from a tank labeled "non-potable" and decided to test the water himself. He tested samples from dozens of flights and found only a couple that met drinking water standards. He turned his results over to the EPA who forced airlines to put warnings on their lavatory sinks.

It has to do with the unsealed tanks.
posted by Pollomacho at 8:18 AM on September 29, 2005

That's really cool, Polomacho. Any links?
posted by Optimus Chyme at 8:32 AM on September 29, 2005

may be potable.

Speaking of which, why do we call drinkable water "potable"?
posted by goethean at 8:54 AM on September 29, 2005

I was just looking for some links! His name is Zach Bjornson-Hooper. Apparently this same kid is working on an energy source derived from the growth of e. coli bacteria.

Here's a google cache of an article on him.
posted by Pollomacho at 8:59 AM on September 29, 2005

Speaking of which, why do we call drinkable water "potable"?

Because potable means "fit to drink."

[Middle English, from Old French, from Late Latin pōtābilis, from Latin pōtāre, to drink, from pōtus, a drink.]

All liquids are "drinkable."
posted by desuetude at 9:18 AM on September 29, 2005

All liquids are "drinkable."

Glass? Silly Putty?
Just hasslin' you, now that the OP question seems to be answered.
posted by Aknaton at 9:28 AM on September 29, 2005

Thanks, Pollomacho. Your reward for giving such helpful answers is you get asked a followup question.

The article you linked to included the following:

Skinner suggested that airline passengers who have weakened immune systems avoid drinking airline water, coffee and tea, and use bottled water instead. Those people also should avoid using airline water to wash their hands, added Benjamin Grumbles, the agency's acting water director.

I realize this is directed at people with compromised immune systems--but it does seem to imply that if the water is contaminated, you are better of NOT washing your hands with it... Does that contradict your original answer, or am I just confused?
posted by yankeefog at 4:44 AM on September 30, 2005

Well, if you take a huge dump and smear coliform bacteria from your crap all over your hands, now your hands are covered in coliforms.

Where did those bacteria come from? Inside your body, that's where. That suggests to me that it's probably not such a big deal if you're exposed to them.

Other people's bacteria, though - look out, immunocompromised guy.
posted by ikkyu2 at 2:26 PM on September 30, 2005