spaceSpace and Physics

Russia Now Knows Why Their Water On The ISS Turned Yellow – And The Answer Is Pretty Grim


Jonathan O'Callaghan

Senior Staff Writer

Water water everywhere, but not a drop to drink. NASA

When you’re orbiting several hundred kilometers above Earth, having access to clean water is pretty crucial. So it was probably some cause for concern earlier this week when Russia’s water on the International Space Station (ISS) started turning yellow.

The ISS is split into two segments, the US and Russian side, with both having different water supplies. The Americans have water with few minerals that are treated with iodine salts, while the Russians have heavier water with more minerals and silver salts.


But earlier this week it was reported that some problems had occurred with Russia’s hot water supply. They found it was turning yellow, with an unknown chemical substance (admixture) causing the change in coloration. So they had to use water from the US segment while the problem was investigated.

According to the Russian news website TASS, the cause was actually a delightful limescale crust inside a “samovar”, a container that’s used to heat and boil water.

"A household cause is behind the emergence of the yellow admixtures in the water,” Vladimir Soloyov from the Energia Rocket and Space Corporation told the website.

“Routine limescale crust had formed in the water-heating unit, which had reached the end of its service life. There is nothing terrible in that as we are regularly confronted with such things on Earth. The problem is solved quite easily, we will just promptly replace this unit, which cosmonauts normally call ‘samovar’ with a reserve one."


The replacement of such a system was described as being “absolutely normal”, with water from the US side being used in instances like this. The samovar was reportedly replaced yesterday, April 25, so presumably, the Russians will go back to drinking their own water.

They might not have enjoyed the switch too much though, as there’s one other key difference between the water supplies on the ISS. Namely, the Americans recycle their urine, whereas the Russians don’t. They actually also use the Russian's urine, although don’t worry, it’s not that gross.

“Before you cringe at the thought of drinking your leftover wash water and your leftover urine, keep in mind that the water that we end up with is purer than most of the water that you drink at home,” former Canadian astronaut Chris Hadfield noted in 2013.

“That makes the International Space Station its own self-contained environment. That’s a critical step towards living for long periods off of planet Earth.”


So yes, Russia’s water did turn yellow. But don’t worry, it had nothing to do with urine – although ironically, they probably did end up drinking some as a result.


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