Environment & Science

Space baths and other water saving tips from astronauts

NASA astronaut Tracy Caldwell Dyson inside the International Space Station's Cupola, a seven-windowed turret-like module on the orbital outpost.
NASA astronaut Tracy Caldwell Dyson inside the International Space Station's Cupola, a seven-windowed turret-like module on the orbital outpost.

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You may have heard of  "Navy showers," but what about "astronaut baths"?

Astronauts on board the International Space Station are experts at saving water, since supplies up there are limited.

Here are a few of the ways space explorers conserve H2O, according to former ISS resident and NASA astronaut Tracy Caldwell Dyson.

1. Forget "Navy showers," astronaut take "space-baths"

A Navy shower is when you only use water to rinse yourself, shutting it off while you scrub and lather. The term comes from life on board Navy ships, where fresh water is scarce.

This kind of shower might use about 500 ounces of water.

That's not bad, but Caldwell Dyson says in space, you typically only use about 20 ounces of water to clean yourself.

Obviously, astronauts can't run faucets since without gravity water would just float off in all directions. Instead, they use wet rags to clean off.

"It's a plain old sponge bath is what it is, and that saves a lot of water," said Caldwell Dyson.

She says it might take another 40 ounces to wash her hair, but she didn’t do that every day.

"You still felt pretty fresh."

2. Use a waterless space toilet

Typical toilets might use a gallon and a half for every flush. In space the toilet uses zero gallons.

Instead, the bathroom system relies on suction, says Caldwell Dyson.

Astronauts sit on a hole that uses a vacuum to capture their solid waste.

Liquid waste is siphoned into a hose with a yellow tip. That device is nicknamed "Mr. Thirsty."

(Space toilet on the International Space Station in the Zvezda Service Module. Photo via NASA)

3. No dishes and no laundry in space

Food in space may not be the most appetizing, but it doesn't leave a mess, said Caldwell Dyson.

It comes dehydrated or thermally stabilized in packages like military rations. Once you eat the meal, you toss out the wrapper. Zero water wasted on dishes.

Similarly, astronauts have to dispose of their dirty socks and underwear since there is no washing machine on the space station.

However, when it comes to outerwear, astronauts simply do what many of us did in college: they wear the same outfit over and over. 

"We have the same pair of pants for 45 days," Dyson Caldwell said.

After 45 days, she said you get the luxury of putting on a clean pair of slacks. Despite all of this, she said the crew never seemed to smell.

"You gotta wonder, do you just get use to how everybody smells because you all smell the same?"

4. Recycle EVERY drop

Astronauts learn to use and reuse lots of things, and water is no exception.

On board the space station there is "regenerative system" that captures moisture in the air and processes it into drinkable water.

"Everything from your breath to your sweat," Dyson Caldwell said.

They also recycle urine water by purifying it until it is drinkable.

"It's not bad," she admitted.

In fact, she remembered when her crew did a taste test between water from fuel cells brought by a space shuttles and the recycled water from the ISS.

"Folks preferred the space station pee water."