now that summer's winding down and
you've already spent lots of time in the
water
i want to show you now how to figure out
how much pee is in any pool
there's actually a lot of misinformation
on the topic of pee and pools
so i'm gonna do some experiments on my
own along with some clever science
people in foreign lands and spoiler
alert
some of the results are good news and
some aren't
so let's jump right in
so this first experiment is to determine
how much pee
is in an actual sample of pool water
using an ingenious method
so i got two samples from my friend's
community pool where lots of people swim
one from the pool and one from the spa
and then two samples
from a friend's backyard again one from
the pool and one from the spa
i also collected samples from the source
water at each location as a control
and i'll explain why in a minute now
that i have my samples i needed to
quickly get to my scientist friend
lindsay in canada
but lucky for me i knew a shortcut
[Music]
we are now in the lab of the university
of alberta
and this is lindsay blackstock and she
is basically a genius
so you are going to help me determine
how much pee is in these samples because
we know people pee in the pool
yes we have strong evidence that people
do pee in the pool
so we're going to try to find a way that
we can measure that p
without actually measuring p i'm going
to apply my new strategy
based on the amount of artificial
sweetener that's in the pool
we know artificial sweeteners don't come
from anywhere
except for urine so that's the only
logical source for them if we find them
in the pool
and we know how much artificial
sweetener is in the average person's pee
right and then using that we can
estimate how much pea is in the pool
got it so we're going to take this
sample we're going to bring it over to
our sample prep bench
we're going to filter it transfer it
into some special vials
into this instrument which is a liquid
chromatography
system of course so this instrument
is going to concentrate our sample
before it passes it on over to the
second instrument which is a mass
spectrometer
and the mass spectrometer is able to
detect the individual little
artificial sweetener molecules one by
one
love it let's get to work bring it on
over there
[Music]
before we run the samples let me explain
why i find lindsay the scientist's
solution
so brilliant you can actually take a
sample of pool water and directly
measure the amount of urea in there but
the problem with that is humans also
excrete urea through things like sweat
which is also very common in a pool so
you can't tell how much of that urea
actually came from pee to get around
that she looked at the amount of a
certain artificial
sweetener in the sample called a sulfane
potassium which is really common in food
products such as these
oh and also all of these so pretty much
everything the reason drinks like these
are zero calories is because you taste
the acetyl flame potassium sweetener
but the chemical compounds aren't broken
down at all by your body
so more than 99 is passed through in
your pee
within 24 hours and therefore the only
reason this would be in the pool
is if it passed through a person first
and just to be sure we measured the
source water at both locations
because sometimes trace amounts of the
sweetener can be found in the water
supply and if so
we just subtract that from the results
and i love this because we've all
wondered how much pee
is in a specific pool but lindsey
figured out a really clever way to use
proven science
to actually answer the question
[Music]
[Applause]
the mass spectrometer takes about an
hour to get results so while we were
waiting
lindsay told me something that really
surprised me chlorine in pools is
obviously
really helpful because it breaks down
harmful bacteria viruses and microbes
that would be harmful or even
potentially deadly to humans
however there is one big downside
and that is it reacts with urine to
create a byproduct called trichloramine
so trichloramine is what's responsible
for that chlorine smell
that you might get when you enter into
an indoor swimming facility
it's also smell chlorine like straight
out of the bottle it
kind of has that chlorine-y smell yeah
but but the smell that you smell
in a pool is trichloramine like this is
the compound responsible for that
characteristic swimming pool smell if i
look skeptical here it's only because
i was so i devised an experiment of my
own
to see if this was really true for the
experiment i got two
five gallon buckets and filled them with
pure water then i added four times the
recommended concentration of chlorine
for that volume of water to both buckets
and then
only in the bucket labeled b i added
just a little bit of pee
and i let it sit for a couple days all
right so it's been three days
so this is the moment of truth so the
first thing i notice
is visually they look the same you can't
tell one bucket from the other
as far as color of water goes so i'm
going to start and smell this one first
[Music]
so that doesn't smell like anything that
smells just like water even though this
has
four times the recommended concentration
of chlorine for this volume
which makes me nervous to smell this one
[Music]
what that is crazy
this smells like a pool even though the
only difference between these two
is this has a little bit of pee in it
this is a nostalgic smell this smells
like
summers and vacationing at hotels with
pools and
water parks turns out it was just pee
so if trichloramine which again is what
is produced when pee reacts with
chlorine
was just that classic pool smell that's
not that big of a deal
but the problem is it's kind of bad news
for both your lungs
and your eyes when your eyes are really
red after swimming for a while
that's actually because of the
trichloramine from the pee
not the chlorine trichloramine also
causes things like asthma
in fact studies show asthma is more
likely to occur among elite swimmers
than any other high level athlete which
now makes sense because michael phelps
admitted to always peeing in the pool
and he says all his buddies do too so be
cool
and don't pee in the pool now let's go
see lindsey's results in lindsay's
research she sampled
20 public swimming pools and 10 public
hot tubs the average concentration of
sweetener for the pools
was 470 nanograms per liter and for the
hot tubs was 2247. so after running all
of my samples we found that here in my
friend's
backyard pool they had a concentration
of artificial sweetener
of 69 nanograms per liter which equates
to just
under a gallon of pee which is actually
much lower than the average but that
makes sense because
this would seem much less use than a
public pool their spa had a higher
concentration than the pool at 103
but since the spa contains much less
volume that equates to about this much p
so far not bad and then in this public
community pool we had 27 nanograms per
liter of artificial sweetener
concentration which for this volume is
again a little bit less than a gallon
and the spa was higher at a
concentration of 335
which is about this much for the volume
of the spa so the concentration of
artificial sweetener in this pool and
spa
is much much lower than the averages
lindsay saw
in the 30 samples she collected which
leads me to believe that the water has
been completely replaced recently
which happens from time to time for
various reasons if this pool had the
average concentrations reported by
lindsay
for these volumes we would expect to see
over a gallon of pea
in the hot tub and about 13 gallons in
the pool
if you want an estimate of the p in your
own pool
i came up with a simple equation after
talking with professor ernest blachley
of purdue university
who mentioned that studies have found
that swimmers introduced between 25
and 80 milliliters of urine per swim
session you take the average number of
swimmers that were in your pool per day
during the summer and then you multiply
that by 1.2
that's how many gallons of pea are in
your pool at the end of the summer and
if you think your friends and neighbors
pee
more than average use two as the
multiplier
and if you think they are more on the
courteous side of the range use one half
as the multiplier as a general rule of
thumb though public pools
about this size will contain
approximately 13 gallons of pea
and olympic pools will contain brace
yourself
over 130gb gallons there are some
caveats to these generalizations so
check out the links in the video
description
for published papers from both
scientists lindsay and professor
blachley so in conclusion
what does this all mean like is this
something to be grossed out about for
starters let me just say pee is
generally considered to be sterile
meaning it's free from bacteria and any
living things
you could totally drink the stuff and
not get sick in fact in some cultures
that's totally a thing you drink the
grandson's pee and it's gonna help you
additionally urine is made of 95 water
and just 5 of dissolved solids like the
urea stuff we've been talking about
the fact that pea is so dilute at 95
pure water is in part disappointingly
why it's really hard to make a chemical
you could add to any pool that will
magically turn
blue if someone pees in it having said
that i suppose it's still a little gross
knowing you're swimming and even just a
small amount of pee
but i feel the benefits to your
happiness and well-being that can come
from swimming
far outweigh any sort of gross factor or
minor health risks i guess at the end of
the day my advice would be to be cool
and don't be in the pool and then at
that point just keep swimming
just keep swimming just keep swimming
swimming swimming just maybe take a
shower when you're done
you