So, where I work they have these high-efficiency urinals installed. Above them, there is a placard that brings this fact to your attention, which reads:
This urinal flushes with only 16 oz. of water, saving 88% more water per use than a standard one-gallon urinal.
I cringe every time I read it as I'm taking care of my business. The big problem here is not the math, as it is obvious that the 88% number comes from 16oz / 128oz (one gallon). The problem is the use of the word "saving," which makes the statement completely untrue.
In order to compare two things, a baseline must be established. Person A earns 25% more than Person B. So, we first establish a baseline. In this case, the baseline is what Person B earns. Next, we compare what Person A earns to what Person B earns. Simple.
What is the baseline for the claim above? In order to figure out how much more water the high-efficiency urinal saves compared to the standard one-gallon urinal, we need to establish the standard urinal's level of saving.
Urinals don't save any water, instead they consume it. And, there lies the problem. The baseline is a one-gallon urinal that saves zero water. The current high-efficiency urinal also saves zero water. Thus, there is no difference in the amount of water saved by the urinal. This makes the entire sentence somewhat nonsensical, and it irks me.
Those who wrote that sentence need only make a minor edit, creating the much better worded (and true) statement:
This urinal flushes with only 16 oz. of water, consuming 88% less water per use than a standard one-gallon urinal.
That's it. I'm done ranting about this one... well, that is, until the next time I have to go take a piss while I'm at work.