Here’s an idea. Once you’ve already split the water molecules with electrolysis, you should throw those streams into separate mass spectrometers, but without the detector obviously. The idea is, that with ions flying in a magnetic field, their mass would determine where they land. Anything that isn’t the right kind of isotope, let alone right kind of atom, would be separated into the waste stream.

The number one thing I love about Randall Munroe’s particular brand of nerd humor is how genuine he is. His fascination with the natural laws of the universe is just that. It’s not something he uses to hold himself over other people or to create in-groups and out-groups of people who know and people who don’t. Even when his content is too complex for the average person it never has that subtextual “well you just wouldn’t get it because you’re not smart enough” vibe that so much other nerd humor has (looking at you big bang theory). He’s genuinely inviting the reader to learn about whatever it is, whether they ultimately do or don’t. He doesn’t have that weird inferiority complex people get sometimes where people feel the need to defensively push others away from their interests to feel better about the fact that their interests happen to be niche in some way. He doesn’t use it as a vehicle to fuel his ego. I’ve joked before that he’s my “celebrity crush” but it’s really just that he truly, genuinely wants to show you something he thinks is cool (and at least a little humorous) and as someone who’s met a LOT of snobby nerds, I’ve always deeply respected that he isn’t one. - sincerely, a professional vibe-checker (like, actually).

The joke about adding well water back in again at the end is “correct”. Reverse osmosis removes 100% of the solids from the water, but drinking water usually contains small quantities of solids - you can see a breakdown on the label of some bottled water. Completely pure water would leach all of the solids that have built up on the insides of water pipes over the decades, and leaches away the protective oxide layer from metal pipework, causing it to corrode surprisingly rapidly. It also tastes pretty shitty - kind of “dead”. So a small amount of high-solids water is mixed back in after RO to bring the water back to normal levels.

All that other shit in the diagram? No. Purification and treatment takes place after the mixing step, it would be crazy not to.

Least convoluted factorio seablock recipe

I’m going to refer to lakes as “cosmic ray sterilization basins” from now on.

Another article tag on explaixkcd that makes you go hmm 🤔😄

WATER. JUST PLAIN WATER. NOTHING DONE TO IT, JUST PLAIN WATER. POSSIBLY DRINKABLE. - Do NOT delete this tag too soon.

lol all that just to add well water back in at the end

This is how I felt trying to build a water purification system in Oxygen Not Included

What would be required for my wife to drink tap water.

Is this to scale?