Save Water With An Incinerating Toilet

Why the two-tier toilet bowl? via photopin (license)

By Lars Sorensen

Finding articles on residential solar power and wind generators is easy, but what has somewhat less of an Internet presence are articles on water-saving/recycling technologies, such as greywater recycling systems and alternative sewage disposal systems. All of the press given to alternative energy sources is well-deserved—these are vital components to off-grid living—but given the planet’s rapidly decreasing fresh water supply, issues of water rationing and sewage disposal are quickly becoming matters of urgency, regardless of how unsexy the topic of sewage may be.

What are the differences between compost toilets and incinerating toilets?

Articles on off-grid sewage disposal usually center around compost toilets – a system comprised of the toilet itself, and a waste storage chamber placed underneath the toilet. The storage chambers of modern composting toilets are also designed to act as a treatment chamber; drainage systems remove excess water from the waste, and the waste undergoes a composting process, aided by manually shifting the waste periodically with a rake or shovel to promote aeration. Composting toilets can be as simple as a non-flush toilet placed over a pile of sawdust, or as advanced as a low-water flush toilet which sends waste through plumbing to a separate treatment chamber, where it’s shifted and aerated mechanically.

Incinerating toilets, by contrast, are completely dry systems which speed up the breakdown process dramatically by way of intense blasts of heat. They’re still a rarity in the states, with a handful of brave pioneers having successfully broadened the horizons of their local town zoning boards. Compost toilets and incinerating toilets both have two very important points in common: 1) they eliminate the need to install a septic system, saving homeowners anywhere from $2000 to $7000, and 2) they give builders the freedom to construct a new home anywhere without regard to drainage or water re-routing issues.

The differences between electric and propane incinerating toilets

An electric incinerating toilet uses electric heat to burn waste, creating a pile of sterile, odor-free ash within an hour’s time. Newer models, such as those sold by Incinolet, look somewhat like a standard toilet, though with a metal base and no water tank. Before using, a specially designed paper bowl liner (similar to a large coffee filter) is placed in the bowl of the toilet. When ready to flush, a foot pedal at the base of the toilet is pressed, sending the filter and its’ contents into an incinerating chamber. If the toilet is needed by another individual immediately after the first user is finished, the toilet can collect and hold waste from another user before incineration is activated.

Once in the chamber, waste is incinerated by a heating coil, at a temperature between 970º and 1400º F. Smoke and foul odor from the incineration process filters through a catalyst located towards the back of the unit, which helps control the odor before sending fumes out through the exhaust vent. An exhaust fan within the unit continues to send fumes out through the vent until the coil has cooled enough to stop burning. The end of the exhaust vent is designed to protrude through one’s roof like a small stovepipe, sitting well above window level to prevent any remaining odor from re-entering the house. The end result of this process is a small pile (roughly one Tbsp.) of germ-free ash that costs anywhere from $0.25 to $0.30 to operate, per burning cycle.

By contrast, propane incinerating toilets require no electricity whatsoever, and resemble a typical outhouse-style toilet more than a modern toilet bowl. Wastes drop directly down into a holding chamber, and a liquid MK1 anti-foaming agent is manually added through the toilet opening if liquid wastes are present. The toilet seat is then lifted, a firewall cover plug is dropped down over the opening, and the push-button pilot light is ignited. From here, the user adjusts the gas cock handle to the “ON” position, and the waste is burned between 1 and 4 hours, depending on the amount of waste. Propane incinerating toilets cost a few hundred dollars more to install than their electric counterparts, due to their more complicated venting systems. Additionally, the gas fixtures of a propane incinerating toilet need to be inspected annually, making them more high-maintenance than an electric model.

The advantages and disadvantages of incinerating toilets

Once again, the most obvious advantage an incinerating toilet provides is the freedom to construct a new home anywhere, with no regard to septic systems or drainage. For the conservation-minded, there’s also considerable peace-of-mind in knowing that dwindling fresh water supplies aren’t being used to flush wastes away. Even the cost of an incinerating toilet doesn’t count as a disadvantage: the price of either falls somewhere between $1500 and $3000, but that cost is balanced by the savings that come with not having to dig and install a septic system, or hook up traditional toilet plumbing to that system. Another advantage, when compared to composting toilets, are the lack of sitting wastes, which can lead to foul odors with old-fashioned, non-flush composting systems.

So what are the disadvantages? The first that comes to mind is the potential cost associated with using electric or propane to fuel incineration. As stated earlier, an electric toilet only uses around $ 0.25 worth of electricity to operate: a couple living off-grid will not likely overtax whatever alternative energy source they’re using. On the other hand, a family of five who spends much of their time at home may find that they’ll need to spend considerably more on solar panels and wind generators than they had initially intended. With propane toilets, propane fuel and anti-foaming agents are going to be a continuous cost that has to be factored into an off-grid lifestyle budget.

The last two disadvantages are much more minor: the lack of nutrient-rich treated waste for crop-growing purposes can be disappointing for those who garden, and off-grid enthusiasts may be turned off by using an outhouse-style toilet, as well as having to look at their waste before applying the anti-foaming agent.

Final thoughts

Greywater still requires some sort of septic system, though companies such as Envirolet sell residential greywater recycling systems for $3000 that can treat and reuse water from the sink, shower, and laundry. When paired with a deep water well and a residential greywater recycling system, incinerating toilets eliminate any septic treatment concerns, put a definitive end to wasteful water usage, and make off grid home owners truly independent of municipal water supplies and the bills that come with using them.

Lars Sorensen enjoys keeping in shape, preparing healthy meals, and enjoying the serene beauty of the great outdoors.

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