United StatesEnvironmental ProtectionAgency

Office of WaterWashington, D.C.

EPA 832-F-99-072September 1999

Water EfficiencyTechnology Fact SheetIncinerating Toilets

DESCRIPTION

Incinerating toilets are self-contained unitsconsisting of a traditional commode-type seatconnected to a holding tank and a gas-fired orelectric heating system to incinerate waste productsdeposited in the holding tank. The incinerationproducts are primarily water and a fine, non-hazardous ash that can be disposed of easily andwithout infection hazard.

APPLICABILITY

Though traditional water-flushing toilets are widelyused throughout developed regions of the world,their use is not always feasible. For example:

C In rural areas where no municipal sewagesystem exists, or where installation of septicsystems is impractical or prohibitivelyexpensive due to shallow soils, steep slopes,high groundwater levels, or extreme coldweather conditions.

C For remotely located roadside rest areas,where connection to a piped sanitary systemis impractical and the cost unjustifiable.

C For work crews operating in areas wherepermanent toilets are not available.

C In marine vessels, for which discharge ofuntreated waste into bodies of water isprohibited; human wastes must either bestored in tanks while at sea or be treated priorto discharge.

C In areas where water is scarce due to droughtor other environmental conditions and theneed to conserve water motivatesconsideration of alternative, water-free toiletsystems.

C Where community, environmental, and healthorganizations have concerns regardingexisting sewage disposal practices, especiallyseepage of contaminants into local watersupplies from improperly functioning septic orother treatment systems, or exposure ofresidents to improperly dumped wasteproducts from rudimentary collection pailscalled “honey buckets.”

All of these situations are potentially suited to theuse of incinerating toilets which are portable, water-free, and sanitizing.

ADVANTAGES AND DISADVANTAGES

Often touted as a “pollution-free” technology,incinerating toilets have some clear advantages overmany traditional methods of sewage disposal. Thereare also disadvantages that should be considered.

Advantages

C Uses no water.

C Incineration cycle produces a fine, sterile ashthat can be thrown in the trash.

C Ash is space-saving; as little as onetablespoon of ash is generated on average peruse.

C Incinerating toilet systems are portable,simple to install, and easy to use. Can beinstalled in remote areas, either for temporaryor permanent use. Can be installed inunheated shelters, even in freezingtemperatures.

C Relatively odorless in comparison to morecommonly used storage-in-disinfectantportable toilets.

C In most areas, can be used in unheatedshelters without fear of freezing.

Disadvantages

C Incinerating process destroys nutrients in thewaste; ash is inadequate for replenishing soilnutrients.

C Incinerating requires energy, resulting inhigher average energy costs for users.

C Units are not entirely pollution-free; bothportable electric generation (for remotelocations) and propane fuel burning producesome air pollutants.

C Anti-foam agents, catalysts or other additivesare typically required for use.

C Some models cannot be used while theincineration cycle is in progress.

DESIGN CRITERIA

Specific design criteria depend on the type of energyused for incineration. Incinerating toilets aredesigned with a chamber that receives and storeshuman wastes until ready for incineration. Theincinerating chamber is typically composed ofstainless steel or a cast nickel alloy. The chamber isaccessed through a toilet seat support—part of ahousing made of non-corroding fiberglass reinforcedplastic or similar material—having a sealablereceiving opening for introduction of wastes into thechamber. Vapor and products of combustion arefed by blower fan to a venting system which may beas simple as an exhaust pipe, or which may alsoincorporate an afterburner or other odor control

system. Not all units can be used during theincinerating cycle. Some units require initiation ofan incinerating cycle after each use while othersallow for multiple uses before an incineration cycletakes place.

Electric Incinerating Toilets

The Incinolet electric incinerating toilet(Blankenship/Research Products, 1999) is designedwith a paper-lined upper bowl that collects newlydeposited waste. To “flush,” a foot pedal is pressedcausing an insulated chamber cover to lift and swingto the side while the bowl halves separate, droppingthe paper liner and its contents into the chamber.When the foot pedal is released, the chamber isresealed and the bowl halves return to normalposition.

Incineration is initiated by pressing a “start” buttonafter each use of the toilet. The manufacturer doesnot recommend using the toilet multiple timesbetween incineration cycles. The toilet can continueto be used while incineration is in progress. Oncethe “start” button is pressed, an electric heating unitcycles on-and-off for 60 minutes while a blowermotor draws air from the chamber over a heat-activated catalyst bed designed to remove odorcomponents. Upon leaving the catalyst bed, the airis forced out through a vent line. Makeup air forthe chamber is drawn from the room in which thetoilet is operating. The blower motor continues tooperate after the heating cycle to cool the unit. Acomplete cycle takes from 1.5 to 1.75 hours.

Five models of the Incinolet electric toilet areavailable: two for fixed locations (one four-personcapacity and one eight-person capacity); twomobile- location units for motor homes, trailers andboats (one four-person and one eight-person); anda urinal (eight-person). The smaller capacity unitsare designed for 120 volt service, while the largerunits require 240 volts. All models retain the samefundamental design principles described above.

Gas-Fired Incinerating Toilets

Propane or natural gas-burning incinerating toiletsare manufactured by Storburn International, Inc.(Storburn, 1999; Lake Geneva A&C Corp, 1977.)

These units are equipped with a three gallon storagechamber which can accommodate 40 to 60 usesbefore initiation of an incinerating cycle. To initiatethe cycle, an anti-foaming agent is manually addedto the chamber, a pilot is lit using a built-in piezo-electric igniter, and the burner is activated. Thisprocedure automatically locks down the unit so itcannot be used while the burner is in operation. Acomplete incineration cycle takes approximately 4.5hours for a full chamber.

PERFORMANCE

Evaluation of 19 On-Site Waste TreatmentSystems in Southeastern Kentucky.

A comparative “blackwater” (human excrementwaste) treatment study, known as the AppalachianEnvironmental Health Demonstration Project(AEHDP), was conducted in southeastern Kentuckyduring the 1970s (U.S. EPA 1980.) As part of theyear study, twenty prototype systems representingseveral alternative treatment technologies wereinstalled in private residences in southeasternKentucky during 1970 and 1971, including sixincinerating toilets. The region used for the studywas mountainous, characterized by shallow soils,steep slopes and high groundwater, having ademonstrated need for alternative treatmentmethods. Further, the study was performed in alow-income area where cost of installation andoperation was a critical consideration.

Two of the six toilets used in the study wereIncinolet brand units and the remaining four wereDestroilet brand propane-fired toilets. Since theDestroilet is no longer on the market, and wassignificantly different in design from propane-firedtoilets available today, findings related to theDestroilet are not relevant to this Fact Sheet.Results pertaining to the Incinolet electric toilet,however, are still pertinent.

The two users of Incinolet toilets complained ofincomplete waste incineration. Scraping of partlyburned feces from the walls of the incineratingchamber was periodically necessary. One householdusing the Incinolet deemed the operating costexcessive, and abandoned the incinerating toilet infavor of their outdoor privy after approximately six

months. The second household used the Incinoletfor approximately three years; however, toilet usewas intermittent over this period and the outdoorprivy was preferred because of incompleteincineration of waste products. The secondhousehold installed a septic system to replace boththe Incinolet and the privy. The studyacknowledges that the Incinolet manufacturersubsequently added catalyst as an incineration aid,but notes that the basic configuration of the unit wasunchanged.

Cold Weather Operation Study of a StorburnPropane Combustion Toilet

Researchers from the Alaska Area Native HealthService and from the University of Alaska,Anchorage, conducted an examination of Storburnpropane combustion toilets whereby honey bucketwaste was collected over nearly a month andburned in a Storburn toilet using various batch sizesand burn cycle times (Ritz and Schroeder, 1994.)All burn cycles were conducted while the toilet andpropane fuel tank were located outdoors, withambient temperatures reaching as low as -11°C.Anti-foam reagent was added to the contents of thecombustion chamber before each cycle to preventboil-over of liquid waste.

The Storburn was found to effectively reducehuman wastes to ash, even at low ambienttemperatures. On the coldest day tested, theexhaust temperature was measured going from -11°C to 100°C (the boiling point of water) only oneminute after ignition. On average, the ash remainingafter incineration amounted to 2.23 percent of thetotal weight of waste treated in the Storburn. Moreover, microbiological examination of theresulting ash revealed no fecal contamination. Thecoldest temperatures tested did adversely impactincineration, however, because the contents of thepropane tank could not vaporize properly. Tomaintain an optimal fuel supply to the toilet, theauthors of the study recommend keeping propanetanks sheltered or heated when used in sub-zeroconditions.

OPERATION AND MAINTENANCE

Incinerating toilets are generally simple to operate,either involving the press of a button to begin theoperating cycle or the activation of a burner. Thedegree of maintenance required depends on themodel used. Storburn gas-fired toilets have nomoving parts and routine maintenance involvesperiodic cleaning of the burner and regular removalof ash.

Maintenance for the electric incinerating toiletinvolves:

C Regular emptying of the ash collection pan.

C Cleaning of the outer stainless steel surfacesincluding the bowl halves.

C Periodic (every 90 days) cleaning of theblower motor with occasional replacement ofthe blower wheel.

C Cleaning and lubrication of the foot pedalmechanism.

C Removal of bits of paper and dust from thecombustion chamber.

C Annual inspection of the catalyst.

COSTS

According to Incinolet product literature (ResearchProducts/Blankenship), a four-user electricincinerating toilet costs $2,300; an eight-user toiletcosts $2,700. The purchase cost of a propane-burning Storburn is $2,550; a natural gas-burningunit costs is $2,590. Vent kits for both types oftoilet are not included in these costs.

The cost of electricity varies widely according to thelocation of service. Domestic retail energy pricescan vary from $0.05 to $0.15 per kilowatt-hour.The Incinolet electric toilet is claimed by themanufacturer to use 2 kw-h per cycle. Assumingfour users, each using the toilet every 1.5 hours fora use period of 10 hours, the electric toilet wouldconsume approximately 53 kw-h of energy per day,or about 1,600 kw-h per month. At $0.10 per kw-

h, this amounts to $160.00 per month or $1,920annually.

According to the manufacturer, maintenance costsfor the Incinolet include $0.08 per bowl liner used(one per use), a new heating coil every one to threeyears ($89.10 each), and a new blower fan everytwo years ($8.95 each). Using the sameassumptions for frequency of use and replacing partsevery two years, the annual maintenance cost isapproximately $828.

Assuming a total purchase and installation cost of$4,000, for a 10-year service life, the average annualcost (including purchase, installation, operation andmaintenance averaged over 10 years) is $3,148 in1999 dollars for the Incinolet electric toilet.

Ritz and Schroeder performed a life-cycle costanalysis for the Storburn propane toilet (Ritz andSchroeder, 1994.) The authors calculated theannual operational cost per adult to be $233.60 andthe average annual maintenance cost to be $150.Assuming a purchase and installation price of$4,000, the annual cost for four adult usersaveraged over a 10-year service life is $1,484 in1994 dollars. In 1999 dollars (assuming 5 percentinflation per year), this figure is equivalent to$1,894. Since this estimate reflects unit operationunder cold-weather conditions, it may be assumedthat this represents the high end of the cost range;the unit would require less energy for each burncycle when used indoors or in warmer climates, withcorrespondingly lower energy costs.

For more information contact:

Municipal Technology BranchU.S. EPAMail Code 4204401 M St., S.W.Washington, D.C., 20460

REFERENCES

1. Lake Geneva A & C Corp, 1977. Store andBurn Incinerating Toilet and Method.United States Patent US4051561.

2. Research Products/Blankenship. IncinoletElectric Incinerating Toilet productliterature. Internet site at http:/www.incinolet.com, accessed June 1999.

3. Ritz, P. and Schroeder, H.P., 1994. “LifeCycle Cost Analysis of a Storburn PropaneCombustion Toilet.” Paper presented at the8th International Cold Regions Conference,Fairbanks, Alaska.

4. Storburn International. StorburnInternational Inc. Gas-Fired IncineratingToilet product literature. Internet site athttp://www3.sympatico.ca/storburn/,accessed June 1999.

5. U.S. Congress, Office of TechnologyAssessment,1994. An Alaskan Challenge:Native Village Sanitation. OTA-ENV-591,U.S. Government Printing Office,Washington, DC.

6. U.S. EPA, 1980. Evaluation of 19 On-SiteWaste Treatment Systems in SoutheasternKentucky. EPA 600/2-80-101, U.S. EPA,Washington, DC.

The mention of trade names or commercial productsdoes not constitute endorsement or recommendationfor use by the U.S. Environmental ProtectionAgency.

ADDITIONAL INFORMATION

Storburn International, Inc.47 Copernicus Blvd., Unit #3Brantford, Ontario, Canada N3P 1N4.Contact: David Gabriel, OwnerContact: Julie-Ann Friedrich

Research Products/Blankenship (Incinolet)2639 Andjon Dr.Dallas, TX 75220Contact: Carol McFarland

Dr. Herbert SchroederAssociate Professor of Civil EngineeringUniversity of Alaska3211 Providence Dr.Anchorage, AK 99508