What is an incinerating toilet?

EPA's fact sheet describes these as self-contained units: a seat connected to a holding tank, with a gas-fired or electric heating system that incinerates what's deposited. In EPA's words, the products are "primarily water and a fine, non-hazardous ash." That fact sheet dates from 1999, so treat it as background and use a manufacturer's manual for current specifics.

### What is a typical electric cycle?

Here's the sequence for the Incinolet, following its manual:

1. 1Put a paper liner in the bowl before every use. Without one, the manual says urine can run onto the floor and damage the unit.
2. 2Use the toilet, then press the foot pedal to drop the liner and waste into the burn chamber.
3. 3Press the start button after each use. The heater cycles on and off for 75 minutes at the factory setting, and the blower runs another 20 to 40 minutes to cool the unit.
4. 4Keep using it as needed. The manual says you can use it any time during the cycle, but it warns that more than three small urine deposits or one feces deposit counts as an overload that needs more burn time and causes odor.

One cycle uses about 1.5 to 2 kilowatt-hours of electricity, per the manual. There is flame and high heat in the burn chamber during a cycle. Incinolet's site adds that a responsible adult should supervise young children using it.

### Do gas models work differently?

Yes. EPA's fact sheet describes propane and natural gas units with a three-gallon storage chamber that holds 40 to 60 uses before a burn cycle starts, and that lock while the burner runs. That description covers one manufacturer's 1999 design, so ask any current maker how its model runs.

### Who is an incinerating toilet for?

EPA's list is where there's no easy sewer: rural areas without municipal sewer or where a septic system is impractical, remote roadside rest areas, work crews, boats, and places where water is scarce due to drought and people want a water-free toilet. That last one is the reason Arizona homeowners ask about them.

### Power

The manual calls for a receptacle on a 20-amp circuit with a 20-amp breaker and no other appliance on it, and recommends a dedicated circuit. It also says to keep bedding, curtains and other flammable materials away from the unit, and to put a sheet of aluminum under it if vinyl flooring might discolor. The toilet is sold in 120-volt and 240-volt versions. A new circuit is electrician's work, not plumber's work. EPA lists energy use as a disadvantage, "resulting in higher average energy costs for users," so whatever water you save, you pay for in power or fuel.

### Venting

The manual's venting rules are strict:

• Use a 4-inch vent pipe, no more than 10 feet long with 2 elbows. Longer runs need larger pipe.
• Don't use a dryer hose, and don't vent into an attic or crawl space.
• Finish a vertical vent with a rain cap. On a horizontal vent, use a dryer flap or a downturned elbow so wind can't push air back in.
• Leave a way for air into the room, such as door louvers or a gap under the door, and never run an overhead exhaust fan while the toilet is burning.

Improper venting, the manual says, can cause odor in the room and overheating of the unit.

### Ash

Ash is the routine job. The manual says to empty the ash pan daily, or when the ash is no more than 2 inches deep, because build-up shortens heater life. Incinolet's website says most households empty it about once a week, so follow the manual for your model. EPA says ash averages as little as one tablespoon per use.

Two cautions from the manual. Ash is safe to handle when it has burned to a light color; if it's dark, run another cycle. And it isn't fertilizer: the manual says ash is not suitable to use as fertilizer or compost and should go in household trash in accordance with state and local codes. It also says the toilet is designed to burn only human waste and toilet paper, and that burning trash or food scraps voids the warranty.

### Power outages

If waste is burning when the power drops, the manual says you may get smoke and odor in the room, so open a window. When power returns, the fan restarts on its own if needed, but the heater doesn't come back on until you push the button. That matters when a monsoon storm knocks out power. A standard toilet has its own outage quirks, covered in flushing when the power or water is out.

We couldn't confirm that it is, and we couldn't find a rule that names it. Here's what we did find.

• ADEQ's waterless-toilet rule covers composting toilets. A.A.C. R18-9-E303 sets a general permit for composting toilets and defines one as a toilet that drops waste "directly into an aerobic composting chamber." It requires a notice of intent with the manufacturer's specifications and documentation of listing by a national listing organization. An incinerating toilet isn't a composting chamber, so this rule doesn't describe it.
• Maricopa County's septic guidance lists composting toilets among its alternative systems, which must be designed by an Arizona-registered engineer. It doesn't list incinerating ones.
• The manufacturer says the toilet is "not recommended for use by general public or in some rental properties."

We did not find an ADEQ, A.R.S., Maricopa County or City of Phoenix provision that says an incinerating toilet may stand in for the water closet a home is required to have. We also weren't able to read the plumbing code text on this point. So don't assume it counts. Before you buy, ask the building department that covers your address whether it will approve one, and get the answer in writing. If you're not sure whether your lot is on septic or city sewer, how to tell if you have septic or city sewer walks you through it. Permits are part of any bathroom change, and the bathroom remodel permit page covers that side.

EPA's list is short and still fair: burning destroys the nutrients in waste, it takes energy, units aren't entirely pollution-free, and some models can't be used while a cycle is running. It also notes that additives such as catalysts are typically required.

One more limit is clear from the design. It handles toilet waste only. Showers, sinks and the washer still need a drain, so it doesn't replace your sewer or septic connection.

Here's how it compares, using Incinolet's own comparison, so read it as the manufacturer's view:

If your real problem is a bathroom where a drain line is hard to reach, such as a basement, an upflush toilet is the plumbing-side answer, and it still connects to your sewer.

For the toilet itself, mostly no. Incinolet's website says many owners install it themselves, and the wiring belongs to an electrician. A plumber is worth a call to look at your drain and sewer or septic setup and to compare a conventional toilet. HQ Plumbing & Air is licensed and insured and gives free estimates, with the price upfront before work starts.