In the fall of 2022, Permit Sonoma modified the Sonoma County Code to allow for the use of waterless or non-flush toilets. The Sonoma County Code Section 7-13(E)(1), is now in alignment with the local Onsite Wastewater Treatment System Manual Section 21 – Waterless Toilets.
The following are frequently asked questions (FAQs) and answers regarding waterless toilets in Sonoma County.
A composting toilet is a type of dry toilet that uses microorganisms to decompose the organic matter of human waste. A composting toilet uses heat, moisture, air, and time to break down organic matter and to eliminate harmful pathogens and viruses found in human feces.
An incinerator toilet is a type of dry toilet that uses heat, from electricity, to burn biological waste at high temperatures destroying all organic matter, pathogens, and viruses, leaving a small quantity of ash.
Approximately 10-20 gallons per day per person. Current flush toilets use between 1.6 to 2.2 gallons per flush. Assuming 2 gallons per flush and five flushes per day, savings could be approximately 10 gallons per day per person.
Yes, in theory. However, considering that most instances of waterless toilets are retrofits after the septic system has been installed; that waterless toilets can be removed from service to be replaced with flush toilets; and that the hydraulic savings is relatively small compared to the sizing criteria for septic systems (120 gallons per day per bedroom), the County does not allow for a reduced dispersal field in trade for a waterless toilet.
No, waterless toilets are not a substitute for a septic system. However, waterless toilets can augment a septic system by reducing the volume of waste flow from the septic system. However, there are additional wastewater sources (e.g. faucets, showers, laundry, kitchen waste) that will continue to be directed to a septic system.
A building permit is not required to swap out a traditional flush toilet. However, a building permit may be required for a waterless toilet depending on the model and installation requirements for a particular type of waterless toilet.
Some composting toilets have a vault that sits beneath the unit. Modifications to the structure may be needed to accommodate the vault. This would entail a building permit.
An incinerator toilet may draw more electrical current than an older electric panel can supply. In this case, the panel upgrade would trigger a building permit. Running conduit and electrical lines to the incinerator toilet would trigger a building permit.
The permit fee for a standalone plumbing/mechanical/electrical permit is just over $300.00 (July 1, 2023-June 30, 2024). (View current fee schedules.)
Yes. An operational permit (OPR) is used to track the hauling and proper disposal of the composted solid waste, but not for ash from an incinerator toilet. See “Solids Handling / Disposal” for the handling of incinerator ash. As mentioned under Solids Handling / Disposal, on-site land application is not allowed. A fee has not been adopted for the waterless toilet operational permit. However, staff estimate no more 15 minutes to review the paperwork. Any fee would be set based on the time needed to conduct the review.
Any proposed composting chamber shall be certified to meet National Sanitation Foundation (NSF) Standard 41, Non-Liquid Systems, by an American National Standards Institute (ANSI) accredited third-party testing agency.
No. Incomplete composting can leave pathogens, viruses, protozoans, helminths, and other organisms viable in the composted solids. The operation and effectiveness of each unit will not be verified by the County. As such we cannot ensure on-site disposal will be safe for the community or for the environment.
Under the County’s program, the biosolids need to be hauled off by a licensed waste hauler for proper hauling and disposal.
Ash from an incinerator toilet needs to be transported or disposed of in a manner that does not create a public nuisance, as compared to composted material that needs to be haul off by a licensed hauler.
Waste material must be maintained moist but not saturated with liquid.
Temperatures must be maintained within an ideal range.
Waste must be aerated.
When selecting a composting toilet, the consumer should evaluate the following key operational aspects:
Plug Flow: A composting chamber shall be designed to facilitate plug flow of the waste through the composter meaning all treated compost shall be accessible for removal without requiring removal of untreated or partially treated waste.
Moisture Control: The composting chamber must be equipped with an active spray system that maintains the waste is uniformly moist in order for composting to occur. In addition, a method to collect and remove leachate from the bottom of the composting chamber must be provided. Failure to remove excess leachate will result in saturation of the compost pile, which will result in anaerobic conditions.
Ventilation: The composting chamber must be ventilated to allow airflow throughout. A continuous airflow is necessary to ventilate the air drawn down the waste chute from the toilet room as well as to ventilate the waste gases through vents on the roof. In addition, air must be able to circulate around the waste pile to ensure aerobic digestion.
Temperature: To maintain the proper conditions for the aerobic bacteria in the waste, a temperature range between 68oF and 113oF is required. The composting process itself will generate some of the required temperature. However, if air being drawn into the composting chamber is between 41oF and 65oF for a prolonged period, the aerobic bacteria are unable to thrive, and the waste will decompose anaerobically. If ventilation air is below 41oF, the waste will only accumulate, and no biological activity will occur.
Aeration: Human waste is not sufficiently porous to promote aerobic conditions throughout the waste. An organic filler material such as wood shavings, popped popcorn, or coconut husks must be added and mixed with the waste to allow sufficient oxygen in the waste pile.
Aeration of the waste can be performed via the following:
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