Episode 4 of Season 4 goes back to the tank from the last stream. The plan is to pump the polluted air out of it and turn it into a tank for dirty water, and most of the hour goes into that slow job. Once the dirty water has somewhere to go, new bathrooms with showers start working. The rest of the colony slides in the meantime: food runs out, the duplicants get sick, and the power keeps failing. When the stream ends there are 15 duplicants, the top bar reads 118 kcal, and the commentary calls it "kind of a mess."
Pumping out the bad air
The stream opens on the loading screen and then in the caves, with the plan said out loud: get the air in the tank "not polluted," then make it a big water tank. The pipes are already set up from last time. The air gets vented off to one side for now, a ladder comes out, and a floor goes in to close the space.
Then the pump stops. "I'm actually just out of power." The only power option so far is manual generators, and raw metal is short too. The air pressure down in the tank is "very high," so there is not much room to push the gas.
The duplicants also refuse to haul away the things lying on the floor. The cause turns up after a while: there is nowhere to store slime. Once there is, the sweeping starts. Another cook gets the job, and a few duplicants move up a rank on the jobs screen.
A dirty water tank
The tank gets a new job: "this is going to eventually be a dirty water tank." A bottle emptier goes in, so the polluted water the duplicants carry around in bottles ends up down below. A temporary coal power plant is planned on one floor, and the research turns to power. Over the stream the print choices bring in four more duplicants, Max among them.
A fish near the dig gets a warning: "Are you gonna go down here fish or are you gonna die?" An egg out there stays unreachable, and later the commentary says, "I guess the fish died."
The gas "is slowly going down." Some of the rock can only be dug by miners, "because of the material." A floor goes across the tank with a hole in the middle for the bottle emptier, and a "really ugly pipe" carries dirty water from the new bathrooms over to the tank. The vent ends up under water and is switched off.
Showers that drain
The alerts pile up meanwhile: food shortage, and everybody sick. The new bathrooms do not work, and the duplicants make messes on the ladders instead. The fix is in the pipes: "Oh, there's an arrow on this." The pipe gets turned around, and polluted water starts flowing down into the tank. "I just saw somebody use the bathroom. Look at that, good job, everybody."
Copying it upstairs
With the showers working, the old bathrooms on the next floor up get torn out so the same setup can go in there. A compost has to move somewhere else. Pipes for clean water and dirty water get laid, but the sinks and showers need metal, and the colony is out.
A building that uses polluted water to make fertilizer goes in on the line from the tank. A farm station follows, and its card says it has to sit inside a greenhouse room of 12 to 96 tiles. One duplicant is hungry, needs the bathroom and is "angry crying, ugly crying."
Out of power, out of food
The new bathrooms only work with power, so old-fashioned outhouses go in downstairs as backups. The commentary adds the other half of the problem: "when there's no power, there's no oxygen." The duplicants keep disinfecting one area, and those orders get canceled. The power menu now shows a Hydrogen Generator.
Where it ends
The top bar near the end shows 15 duplicants and 118 kcal of food, with warnings for food shortage, starvation and "Insufficient oxygen generation." The commentary sums it up as "we're out of power, out of food" and says, "We may start over tomorrow."