And were going to use it to heat this hot tub.

And I'm building a toilet that will use the sun to compost our waste.

- Hu-manure, baby. - Hu-manure?

Oh, my God, it's hot! Ahh!

My God, y'all are gonna have to turn the cameras off while we have a romance!

Both: This is "Shut It Off Asap."

All of this garbage right here is from the entire production over the last week,

which is actually not that much, because we've been trying

really hard to have an eco-friendly production.

But this episode, we are shutting off our waste

which means we don't know where this is going to go.

But it also means we don't know what we're going to be doing with the waste from our bodies.

Bye, my porcelain favorite structure.

It's one of those things that you don't often think about,

your waste in both ways just kind of gets taken from you and dealt with,

but this week, we're going to be dealing with it.

And this is honestly so smelly. That's rich.

So we're going to shut this and figure out a plan.

Us humans create a lot of poop.

290 billion kilograms of feces every year.

So I'm going to figure out how we're going to be harnessing that stuff to create fertilizer.

- Okay. - So we're going to be building a solar composting toilet

that is going to create humanure essentially,

that we're going to be using to create a fertilizer

- to grow trees on the farm. - Whoa. Good luck with that.

I have decided to try and deal with our organic waste.

My hope is to make a compost, which doesn't sound that exciting,

but my idea is to use the heat that comes from compost

and use it to heat a hot tub,

so that after all of this we can relax in a nice bath.

And that is what I'm going to do.

We have picked the hottest day to be building this toilet,

this solar toilet that the farm is going to be using after this.

This is our gift to them-- the place where you take a dump.

So the sun, is actually going to be baking the pee and the poo.

This little bit coming out of the back is going to be where

the pee and the poo actually is, and it's made with plastic

that's going to act like a greenhouse to heat it up.

Then we're going to have solar-powered fans

that's going to be taking out the moisture and the heat.

- Will it smell? - It's not supposed to, in theory.

- Okay. Good luck. - But we shall see.

I don't want the solar toilet to be too far from our cabin,

but since this is my first time building one,

I also don't want it to be too close to the cabin,

and have the smell coming right back into the bunky.

How gorgeous!

I'm here with Dave, who works on the farm,

and he's going to be helping me

do our composting mission to heat our hot tub.

And just how do you create heat with compost?

We'll come back to that in a bit.

Because, Dave, you know a lot about composting, don't you?

I've build a few piles, and I love compost.

Have you ever built one that heated a hot tub?

A manure-heated hot tub?

Um, I'm very curious to see the outcome.

- I have never built one to heat a hot tub, no. - Okay.

So we've already pre-built this.

Why are we using these on the bottom?

The composting process is an aerobic process,

so having the oxygen in there, super important.

- That's for the bacteria, right? - For the bacteria.

Because if it goes anaerobic, you will know pretty much right away,

because it's not going to smell very good.

In an anaerobic environment,

bacteria produce oxygen-free sulfur, nitrogen,

and carbon byproducts like hydrogen sulfide and ammonia,

which stink and are toxic,

and methane, a horrible greenhouse gas.

But with oxygen around, we get nicer things like sulfates,

nitrates, carbon dioxide,

which is still a greenhouse gas,

but not nearly as bad, and water.

I think the first thing we're going to have to do

before we build the pile is put these T-posts in.

- Okay. - And we're going to use those to support the pile.

Okay. Okay.

Do I need my hands here or--

You don't need your hands there now.

It's going to be pretty loud.

- Okay. - All right?

- ( ringing ) - Ooh!

And I think that should be far enough down.

Yeah? Okay.

That looks pretty good. Can you see the bubble?

- Yeah. Yeah, it's not bad. - It's not bad.

So we've got the frame of our crapper up.

We have to make sure it's straight.

That's why there's three straight men with me right now.

- Straight. - And now we can put on the roof.

The flush toilet was invented in 1596.

Up until that point, things we would look at as toilets

varied from chamber pots to just holes in the ground.

Domestic wastewater used for irrigation

has been used since 3200 to 1100 BC.

The city of Lothal around 2350 BC in Gujarat, India

had houses with their own private toilet

connected to a covered brick and mortar sewer network

that emptied either into the surrounding water bodies or into cesspits,

which were regularly emptied and cleaned.

The 11th century castle building room had chamber pots,

but also toilets that were for the first time

actually integrated into the architecture.

The toilet is almost finished, but still not ready for use,

so for now when nature calls,

we just got to figure it out amongst the trees.

And it's just a pee-pee!

They're going to use my nitrogen.

They're going to grow deliciously tall from this.

You might have judged me, but there's sugars, nitrogen,

lots of things in there to feed the microbes.

I just helped thine Earth, okay?

I borrowed this trough from the farm.

We're going to fill it with water,

and our goal is to get that water

to 104 degrees Fahrenheit, or around 40 degrees Celsius,

because that's the perfect temperature for a hot tub.

Our most important ingredient perhaps is our big pile of poo.

And this is going to basically be

a source of heat and food for our bacteria,

that are going to break it down.

Just like humans with food or even cars with gas,

the bacteria combine their fuel with oxygen

in an exothermic reaction, meaning it releases energy.

We're also going to throw in some of our organic waste

that the crew and Greg and I have been making during this show,

and anything ultimately that has lots of carbon and nitrogen

to feed those bacteria so they make as much heat as possible.

So this solar toilet, there was nothing there,

and now there's a structure. It's kind of beautiful.

All the real science and what actually has to happen

with our feces and our urine comes next.

So I'm just enjoying the pristine smell of plywood.

So I'm here with Antonio, who taught me about solar toilets, because I used yours.

- Yup. - It was my first experience.

We don't need to go into any more details than that.

I need your help. You are the solar toilet king in my opinion.

Um, I've never been called that before.

I don't think a lot of people even know that about me, so...

So we are actually going to be using our humanure

to plant trees on this farm.

So why is our waste, which to me feels so disgusting, like, good for trees?

So, in nature, there's no such thing as waste.

Everything is a closed cycle, so humanure is really good

because if you eat good food, then it's loaded with really good nutrients.

Yeah, there's lots of phosphorus nitrogen, potassium,

all the things that these like, chemical companies are selling us fertilizer.

- So we're essentially going to harvest that. - Exactly.

We humans need phosphorous, too.

It accounts for 1% of our body mass.

It forms a scaffolding of our DNA.

It's in our cell membranes.

It's a key element in our tooth and bone minerals.

But most of the phosphorus that we eat actually passes through us untouched.

Depending on diet, about 2/3 of our phosphorus winds up in our urine,

and the rest in in our feces.

The phosphorus available from our urine is approximately

1.68 million metric tons per year--

22% of the total global phosphorus demand.

Mining phosphate to make phosphorus fertilizer is energy intensive

and it can be toxic to local environments.

Experts also estimate that the peak supply of phosphorus will be reached by 2033.

Composting toilets are a way to recoup phosphorus,

save the environment, and reduce the cost of food.

Antonio: So what I always do is I start with a layer of woodchips,

- so that there's already something there. - Yeah, yeah.

Oh, look, I can just hear the turd hitting the plastic.

That's not right. That's not right.

Well, it also helps with emptying it out easy.

- It's cleaner. It's like-- - These are things you need to think about.

And then after you have that, every time you go to the bathroom,

all you got to do is cover it up with the woodchips,

so you don't see anything. So all you see is woodchips.

So the sun comes in. Heats up everything,

especially if you paint it black, and the bin's black.

So it gets really hot, and because it's airtight, that moisture goes in the air,

and basically we're going to vent that out.

- With the solar-powered fans. - Yeah, the solar-powered fan.

The humanure becomes safer as you remove that moisture, and it doesn't smell.

I need to move it over there. I need to conceptualize this with you.

So I'm going to pretend this is full of crap

because one day I'm going to be wheeling it out, right?

Wheeling out the crap!

Now that the foundation and structure are in place for our hot tub build,

we need to add a coiled copper tube to the mix.

Copper is an excellent heat conductor,

and a coiled pipe maximizes the surface area of the metal,

in contact with the hot compost

and the water flowing through it on its way to the tub.

I guess it's just a matter of putting our compost on top of this now?

- We'll put our ingredients to make our compost on top. - Okay. Right, I see.

- So this is not compost yet. - No.

- It's compost once it's all broken down by our microbes? - That's right. Yeah.

Our layers of compost ingredients consist of manure,

rotting vegetables, and straw.

Around 17% of all food gets wasted every year,

and only a tiny bit of it gets composted.

Instead, most end up in landfills

where it produces huge amounts of methane gas,

trapping heat in our atmosphere 28-36 times more effectively than CO2.

And because these landfills lack oxygen,

the waste cannot be properly broken down by microbes,

ultimately creating acid litchi, or toxic liquids,

which can seep into the surrounding area

and contaminate water if not properly managed.

But our compost pile will minimize these negative effects.

We'll be layering our brown materials like wood and straw

that have high levels of carbon between our green materials,

like organic waste and manure that are rich in nitrogen,

to give our microbes the best environment to thrive in.

Generally, what you'll see is the temperature will spike in those first few days.

The earthworms and other larger insects will vacate the pile.

- Oh, because it's too hot. Oh, my God. - Because it gets way too hot.

And that's when there's so much bacteria in there,

so many little tiny metabolisms,

-that's what's creating that really high temperature.

- Okay. - Once the microbes get to work,

they'll use this nitrogen and carbon for their own benefit,

and in the process release heat,

which we will capture in our coil at the center of the pile.