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Thursday, January 27, 2011

Random Musing: Shower Efficiency

Question: How many of you pee in the shower?
Follow up question: Why do you pee in the shower?

Most of you probably answered one of two ways for the first question: 1) I do!  2) Ewwww.
The answer to the latter is probably: to save time and/or water.

FYI, new lesson learned: Do NOT do a Google Image search for "peeing in the shower"
without 'SafeSearch' on. (Unless you're into that sort of thing...)

By now you must have realized this isn't really a post about shower efficiency, but who wants to label their post "Peeing in the Shower"?

Anyway, I was curious to see how much time/water/money you could save by peeing in the shower.

Of course, the plumbing and fixtures are different in each house, but I used the following for easier calculations:
- After a quick search I found that after 1992 all showerheads were required to have a flowrate of no more than 2.2gpm
- The majority of toilets are now 1.6gal/flush models
- First number I found for water costs was $1.50/1000gal. That's $0.0015/gal, but let's double it to account for sewage costs ($0.003).
- Urination times can vary from 5-10 seconds to over a minute. I used 30 seconds as an average.
- Everyone values their free time differently. I used $100/hr. A nice round number, and roughly the average wage for a contract worker.

So... with a little use of the mathematics:

Toilet Cost:
Water- This is a constant 1.6 gallons. In terms of monetary costs: $0.0048
Time/money- The difference here is the fact that you have to unclothe yourself. Women probably take a little longer, but men like not wearing pants more and probably take longer to zip themselves up. Let's assume an average of 15 seconds to pull down/up your pants. 15s at a rate of $100/hr results in a total cost of: $0.42
Total Toilet Cost: $0.4248

Shower Cost::
Since you don't need to worry about getting undressed, the only thing we have to measure is time water is flowing while you pee in the shower.
Again, using an average pee-time of 30 seconds results in 1.1 gallons or water flowing down the drain while you pee. At $0.003, that's $0.0033.
Total Shower Cost: $0.0033.

Clearly, peeing in the shower is more cost effective.

However, if you don't value your time at all, the numbers get closer: $0.0048 vs $0.0033.
On top of that, if you're a long pee-er, you might want to reconsider.
Solve for 'x':
$0.0048 = (x minutes)*(2.2 gal/min)*(0.003 $/gal)
x = 0.727 min = 43.6 seconds.

So if you're planning on peeing for longer than 44 seconds and don't value your personal time, you should ignore this whole thing and just use the toilet.

And two quick polls:
Do you pee in the shower?


What do you think about peeing in the shower?
It saves time and money!
Great post! Now tell me how much money I save by pooping!


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