You've seen pit stop footage with crew members zipping tires on and off. But you may not have seen this thing being swapped out:

That's a bottle filled with water, usually mixed with some combination of vitamins, minerals and/or glucose. Races can be long and grueling, and drivers need to stay hydrated.

The bottle plugs into a hydration system built into the car. From the bottle, an insulated hose routes the water up to a bracket next to the driver's head. This bracket also holds the radio wire. Both drinking hose and radio wire are connected to the driver's helmet, with the drinking tube positioned in front of the driver's mouth.

Racing teams vary on how the fluid is delivered. It can be via pump, which requires the driver to press a button on the steering wheel:

Alternatively, they can forego the pump and the driver can simply sip, as with a straw. (You might wonder why anyone would bother with a pump, which adds weight and another thing that can break; I imagine it's something to do with G-forces.)

That drivers are taking in fluids during a race, raises the question of how they urinate during a race. The ugly answer, at least in F1 is, they pee in their suits. Interestingly, even this requires some planning; to urinate you need to be able to relax your body, which you cannot do while taking a hard corner, so you have to wait for a straightaway. (And if you run out of road before you're done going, you have to pinch it off to take the corners and wait for the next straightaway.)

That being said, there are manufacturers of catheters for race drivers, at least in the off-road racing market. (For the Paris-Dakar off-road rally, you might be in the car for 12 hours.) Males wear a condom-like device attached to a hose. Three condoms of different sizes are included in the kit, obviating the need to order by size.

Women have it a little tougher; the business end of this women's racing catheter is a "urinary pouch" that must be attached with adhesive strips.

Those catheters don't come with reservoirs, just the hose, so I assume different drivers rig up their own containment systems. However, this manufacturer's race catheter has "a long latex hose that is used to run the length of a fire suit pant leg allowing you to discharge through the floor of the vehicle."

And on Quora—where I often see people writing wild things without citing any sources—one person states F1 did the following, which beggars belief:

"[F1 teams developed] a catheter system for the driver in the early 2000's. The suit has a built in catheter that the driver installs and then the suit has a hookup to a reservoir in the car."

So far, so good. Then, this:

"When the reservoir gets full, there is a discharge system that sprays it into the exhaust. The heat of the exhaust instantly vaporizes the urine. It's had little to no impact on the race with only a few drivers mentioning an unpleasant smell from the car in front of them."

If this was ever really done--I can find no evidence--well, they're certainly not doing it anymore. (Also, the credentials of the person who wrote it are "I own a car.")