A Crappy CleanTech Topic: Designing The Toilet Of The Future (Part 2)

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In part 1, I took a quick look at the challenges of designing the toilet of the future, and show that there are serious problems with what we currently do. So far, I’ve only focused on what happens when sewer systems malfunction, but we still need to look at the problems that happen when things go “right” with a sewer system. It isn’t pretty.

After that, I’ll start looking for alternatives in our quest for the toilet of the future.

What Happens When Everything Goes Right?

While these systems do cause a lot of problems with malfunctions, many people would argue for fixing them to reduce malfunctions rather than replacing them. There are a lot of sunk costs there, and while that’s a fallacy, entrenched systems in a society tend to stay entrenched unless there are serious problems with them. Even then, as we see with fossil fuels, people would rather keep what they think works than change.

If we want to fairly compare the poopy status quo with alternatives, we need to look at the costs of proper operation and not just the times things go wrong.

I can’t get into the full spectrum of available treatment processes here, but I’ll give a quick overview. First, the wastewater needs to go from the toilets to a treatment plant of some kind. Sewers in developed countries used to just dump this waste water directly out into the environment including all pathogens, nutrients and toxins, but we’ve since learned that doing that is bad for all involved (humans, animals, plants, river systems, etc.). The treatment plant takes measures to make the waste outflows less harmful to the environment, but still releases whatever is left (that isn’t perfectly clean) into a river or lake in most cases.

There are three things to keep in mind about these processes.

First, they use a lot of energy. Just moving liquids alone uses a lot of energy, both to bring clean water to the toilet and to take the dirty water to the sewage plant. Pumps use a lot of electricity or fossil fuels (especially during construction and maintenance) to do that. Treatments processes vary, but they all involve the use of energy at every step, with the total energy consumed estimated at 30 terawatt-hours annually in the United States alone. Electricity alone is 25-40% of a treatment plant’s operating costs, and a big chunk of overall municipal budgets.

Second, sewer plants don’t put pure water back out into the environment. They’re still often contaminated with excess nutrients that encourage algae blooms and other growth that lowers oxygen in rivers and lakes. They also have things like prescription drugs in them that end up affecting both wildlife and humans once those pharmaceuticals end up back in the water supply. It’s not part of a grand conspiracy to turn people and frogs gay, but Alex Jones was partially right when he said there are chemicals in the water causing sexual development problems. His mistake was to not consider Hanlon’s Razor (never attribute to malice that which is adequately explained by stupidity).

Third, various greenhouse gases end up being emitted during the treatment process. Ammonia and other nitrogen gases, along with methane, often end up in the atmosphere. Sadly, soils worldwide, especially in developing countries, badly need these nitrates to keep growing food.

Finally, the sludge that’s left over after liquids are mostly removed is still a problem. Some smaller sewage systems compost the sludge and put nutrients back into the soil, but in most cases it gets burnt, buried, or put in landfills. This keeps most of the nutrients out of normal food circulation, and contributes to soil depletion and the need for synthetic fertilizers.

Bottom line: it probably just isn’t that great of an idea to pee and poop in clean water and send that for cleanup, because it doesn’t work out like we hope. We’re messing up the environment and the food supply of future generations.

Off-Grid Toilets Point To Known Alternatives

What led me to the horrors I found in this article was planning for some off-grid activities, like camping and RVing. It turns out that toilets operating away from a sewer or septic tank fall into two broad categories:

  • Those that store black water (toilet waste) for later dumping into the sewer
  • Those that dispose of it through other means.

Saving It For Later

Most RVs, as well as other “camping” or “cassette” toilets fall into the first category.

If an RV is at an RV park with hookups, it can connect its toilet and grey water (sink/shower water) to the sewer system or a septic tank with a hose. People using an RV away from parks store poop and pee in the black water tank, sealed away from the campers’ noses, until the owners can get to a dump station and empty the black tank. Grey water can sometimes be safely and legally disposed of by dumping elsewhere or through evaporation.

Vault toilets, like what you’d see in a forest or camping area, work in much the same way. They have a tank underground where the poop collects, and a truck has to come and pump it out periodically. The same goes for the porta-potties, but those have some limited chemical treatments to help with smell and appearance.

These black water storage systems must be handled with great care, often with gloves and careful hand washing, to avoid getting violently ill. They also operate as part of the sewer network, so they’re really not any better. They’re just portable or can operate away from sewer systems.

Dealing With It On-Site

The other kinds of off-grid toilets are often associated with hippies, environmentalists, and other latte-sipping do-gooders. They vary a lot in design details, but the idea is to make the poop safe on-site, or at least start the process of rendering it safe.

The simplest type of toilet in this category is a “cat hole.” When backpacking, many people simply dig a small hole, deposit their waste in it, and then bury it back. This keeps the poop from stinking or spreading disease until it can naturally decompose like any animal’s poop. Temporary latrines (a big, deep cat hole multiple people use for days, often with a seat of some kind over it), pit toilets under an outhouse, etc all use this same technique. When the hole is full, it gets buried and left for natural decomposition.

Basic care does need to be taken to locate these types of natural toilets away from streams and other water sources, or on ground that’s likely to erode before natural decomposition can render it safe. Failure to do so can result in contaminating rivers and streams just like a flooded sewer can. Also, if too many people frequently camp in an area, it’s not going to be safe to do this, as the whole ground would end up full of poop holes, with no place to safely store new poops.

Another answer to this problem is the use of composting toilets, which come in a broad variety of designs. The simplest composting toilets are basically just a bucket that you dump some peat moss or coconut coir into, and then again after each use to cover droppings. This dries one’s poopies out, prevents them from spreading stank and germs, and starts the decomposition and composting process. Fancier designs have a mixer of some kind to stir the poop into the organic matter to promote the beginning of composting, as well as a ventilation system of some kind. These simple setups only start the process, and don’t completely compost the poop or render it safe.

It’s possible to dump these small composting toilets into another composting container to finish the full process over the course of seasons, but it’s also usually safe and legal to dump the contents of these into a dumpster or outdoor trash can as needed if you don’t have access to a composting facility. The process will finish in a landfill just as easily, and is no more dangerous than throwing away a diaper or used cat litter. Commercial and municipal composting is still the best option for the environment and for the future of organic farming for those who can’t compost it themselves.

Larger composting toilet setups are designed to complete the full composting process on-site, sometimes using worms or insects. These often have multiple rotating chambers that take turns taking the loads we leave behind, and then go unused for months or years until the contents can be hauled off to be used as fertilizer. The newly emptied container then goes back into rotation.

There are other types of off-grid toilets that aren’t just storage for the sewers, but I can’t mention them all here. Incinerating toilets, freezing toilets, and many other designs exist. You can read all about them here.

None of that is free or cheap, but it may be cheaper than what we currently do once the public considers the full costs of sewers. They simply aren’t aware of these problems right now.

In part 3, I’ll sprinkle some unwanted realism on top of this crappy situation’s solutions, and then explore how we can deploy these alternatives (or not deploy them) in the real world, both at the household and municipal levels.

Featured image: Photo of a rural wastewater treatment plant in New Mexico. Photo by Jennifer Sensiba.

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Jennifer Sensiba

Jennifer Sensiba is a long time efficient vehicle enthusiast, writer, and photographer. She grew up around a transmission shop, and has been experimenting with vehicle efficiency since she was 16 and drove a Pontiac Fiero. She likes to get off the beaten path in her "Bolt EAV" and any other EVs she can get behind the wheel or handlebars of with her wife and kids. You can find her on Twitter here, Facebook here, and YouTube here.

Jennifer Sensiba has 1984 posts and counting. See all posts by Jennifer Sensiba