We runners have a complicated relationship with portable toilets. We’re happy to see them before (and sometimes during and often after) a race, especially when we’ve been shot-gunning liquids and glucose.

But that minute-plus (on average) we spend in their odiferous confines tends to yield some memorable-and-not-in-a-good-way moments. However, instead of shaking your fist at them, we suggest cutting the portable toilet some slack. Everything from the mysterious blue liquid to the height of the drop to the placement of the urinal has been studied and calibrated to make the best of a crappy situation.

Which intrigued us—there’s a lot more to these things than we thought.

How is the user-to-potty ratio determined?

“There's one toilet per 60 people at a concert,” says Steve Brinton, the vice president of sales and marketing at Satellite Industries, a portable-toilet manufacturer, “but at a race it’s one for every 10 people because of the way they’re used.” Meaning a heck of a lot of well-hydrated runners create heavy traffic over a condensed time period.

In fact, after an informal study of race participants, Ron Crosier, president of Crosiers Sanitary Service, Inc., which services race events, found that 80 percent use the loo in the hour before the start. Companies like Crosiers do provide recommendations, but the race director’s budget guides the quantity and quality of the selection. Units range from $50 to $150, depending on the region and the distance they’re transported; $100 is average, says Crosier, and extras cost. . .extra.

“We charge $10 more for a unit with a hand sanitizer, mirror, purse shelf, and hover handle,” he says.

Why is everything, um, wet?

A survey conducted by Brinton uncovered the obvious: users prefer to hover. In fact, 95 percent of women and 93 percent of men won’t make contact with the seat. Since copping a successful squat (especially with destroyed quads) over those things is to defy physics, it’s no wonder things get messy.

So why not just put a normal toilet over the tank to encourage better aim? Because making room for ergonomic porcelain would shrink the tank and lower its capacity. “All that waste has to be contained within a 44-by-48-inch footprint,” says Brinton. “You need more tank than seat.”

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Are they purposely set up to make chaos out of line management?

Suppliers do make suggestions about how to best configure toilets for optimal use, but ultimately their placement is up to the race director. Sometimes, space constraints mean a line of porta-potties—as opposed to the U-shape used by races like the Hartford Marathon, which lets runners choose from more at a time—is the only option.

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For some bigger races in cities, a line better accommodates the narrow streets and thousands of participants. In that case, banks of 10 toilets should be separated by a 20-foot gap to minimize the chaos. One line per bank, rather than per unit, is ideal.

By promoting one line with signage or tape, one out-of-service (or endlessly occupied) toilet won’t stop up traffic. But the U-shape really is the way to go. “There’s something aesthetically pleasing about them,” says Crosier. “You have a courtyard surrounded by doors, so when you're walking in, you can see very quickly which unit is open.” (Bonus points for atmosphere and cleanliness when a sink station is placed in the middle and the whole configuration is tented.)

What is that smell?

Not that one, the other one. Manufacturers deploy several methods of distracting your nose, including hiding deodorizing disks behind hand sanitizers and adding scents to the tank. The most popular aromas are cherry and bubble gum. In part, it’s because they can be easily produced in-house, unlike many fragrances, and they’re particularly good at masking odors, says Dean Carstens from Satellite Industries. “Cherry was one of the first fragrances used and is still known as an industry standard,” he says.

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How come they always run out of TP?

A race’s budget often determines the quantity and quality of toilet paper, which costs about 25¢ to $1 per roll. How much each unit needs depends on the breakdown of men vs. women—more women means more TP—and the type of event. (In an average race, runners only use toilets at the start for 60 minutes or less.) The industry standard is two to four single-ply 1,000-sheet rolls per stall.

“The number of rolls doesn’t matter near as much as what they are,” says Ron Inman, vice president of Honey Bucket, the company that serviced the Hood to Coast relay in Portland, Oregon. “You can get rolls with 500 sheets or 1,500 sheets. Our rolls are 1,500 sheets, single-ply. Dispensers hold three rolls, and we put an extra roll on the shelf.”

What's the lifespan of a unit?

“Porta-potties will easily last 10 years,” says Brinton. “There are toilets more than 30 years old.” The secret of their durability is high-density polyethylene. The plastic is “relatively pliable,” he says, a key quality when you’re continually hauling the houses on and off trucks. “You want toilets that will absorb impact so they won’t crack and leak—a problem with a lot of the old fiberglass tanks.” High-density polyethylene also won’t rot, host nasty bacteria, or break down from cleaning agents—of which it will see many.

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What happens to everything?

First, workers run a hose from a truck that sucks everything from the abyss. If the toilet is staying put, they spend three to five minutes cleaning it and refilling the blue stuff/precharge. Trucks can carry up to 1,500 gallons of waste and 500 gallons of precharge or fresh water (precharge mix is added once water is in the potty). If the unit is leaving, it’s pumped out, loaded on a truck, and pressure-washed.