What do you get when you mix ammonium chloride, citric acid, hippuric acid, L-histidine, sodium phosphate dibasic, urea and uric acid? A potent approximation of sweat and urine.

Yep, there’s an actual formula for fake bodily fluids.

Why would anyone simulate human excretions?

Love Potion No. 9 it’s not, but this chemical mixture has a pretty useful application in realm of recreational water science.

Let’s take a look at how the National Pool Industry Research Center used this elixir in an experiment.

In 2010, the NPIRC at California State Polytechnic University studied the rapid rise of pH in saltwater pools. Because real live swimmers would present a highly uncontrolled and irreproducible variable, researchers developed the formulation of “body fluid analogs.”

I like to image some lab-coated eggheads whipping up samples of the stuff, sniffing each as though it were a fine wine, and shouting, “Too much sweat! Not enough urine! Throw whole batch out!”

The formula is based on the Judd and Bullock model. Simon Judd and Gillian Bullock are United Kingdom researchers who determined that the average swimmer releases about 50 mL of urine and 200 mL of sweat. They’re the ones who cooked up the “synthetic bather” solution.

Using Judd and Bullock’s recipe card, you can make 58 litters of the concoction. That’s like an entire soda aisle!

NPIRC’s study, however, only needed 3.5 litters – enough to last two weeks. That represents about 55 people splashing around for approximately 21 hours each week.

Turns out, the simulated body fluids didn’t alter the results much. That’s why the study suggests a more “rigorous inclusion of the bather component.”

In other words, let’s use more sweat and urine next time.

You can find the study here.