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Flush Toilets Required?

sjh71nh

REGISTERED
Joined
Jul 8, 2025
Messages
3
Location
CA
Hi, the agency I work for is tearing down an existing building (structural failure) and rebuilding in the same location. It is on a well and the local soil cannot support a leach field. This is a rental property that although on a paved road is quite remote. I have been told that flushing toilets are required by the IPC but as I am doing a code review I cannot find where it says that it must be a flushing toilet and cannot be anything else. Is there a section that calls out flushing toilets only for rental cabin?
 
Maybe CPC 411.2? It says that "all water closets" shall have a certain flush volume, implying that the toilet needs to be a flushing type.

411.2 Water Consumption
The effective flush volume of all water closets shall not exceed 1.28 gallons (4.8 L) per flush when tested in accordance with ASME A112.19.2/CSA B45.1.

Edit: Oh, sorry, saw "CA" as your location and immediately assumed CPC / UPC. My bad... In IPC, I believe the section you're looking for is 425 or 604.4.
 
Thank you for that information. I am looking for the exception to flushing toilet. Currently there are outdoor vault toilets there and the goal would be to replace/reuse the existing toilets instead of installing new flush toilets.
 
Check with the local AHJ or Health Department to see if a composting toilet would be allowed.

Also you can search hear to see another thread and comments: Composting toilet
 

The IPC is silent on this subject. The IPSDC prohibits them. Your state health department may have requirements. You could have it go to a holding tank and have it pumped on a regular basis.

2024 International Private Sewage Disposal Code (IPSDC)​

PRIVY.
A structure, not connected to a plumbing system, that is used by persons for the deposition of human body waste.

302.2​

Privies shall be prohibited. Cesspools shall be prohibited, except where approved by the code official. Where approved, cesspools shall be designed and installed in accordance with Chapter 10.

You mentioned this would be a rental cabin. The IRC 2024 edition has this appendix section

Codes / I-Codes /
2024 International Residential Code (IRC)

Appendix CG Nonsewered Sanitation Systems​






2024 International Residential Code (IRC)​



The provisions contained in this appendix are not mandatory unless specifically referenced in the adopting ordinance.
User notes:


About this appendix: This appendix addresses the considerations that need to be taken into account by building officials regarding the placement and installation of nonsewered santiation systems in buildings. This appendix would permit the installation of a of these systems and provide an exception to the general requirement in the International Plumbing Code and this code that sanitation devices be connected to the building drainage system.

CG101​

INSIGHTS (3)

CG101.1​

The provisions of this chapter shall apply to the installation of nonsewered sanitation systems.
INSIGHTS (2)

CG101.2​

Nonsewered sanitation systems shall comply with ANSI/CAN/IAPMO/ISO CG106.1.
 

The IPC is silent on this subject. The IPSDC prohibits them. Your state health department may have requirements. You could have it go to a holding tank and have it pumped on a regular basis.

2024 International Private Sewage Disposal Code (IPSDC)​

PRIVY.
A structure, not connected to a plumbing system, that is used by persons for the deposition of human body waste.

302.2​

Privies shall be prohibited. Cesspools shall be prohibited, except where approved by the code official. Where approved, cesspools shall be designed and installed in accordance with Chapter 10.

You mentioned this would be a rental cabin. The IRC 2024 edition has this appendix section

Codes / I-Codes /
2024 International Residential Code (IRC)

Appendix CG Nonsewered Sanitation Systems​






2024 International Residential Code (IRC)​



The provisions contained in this appendix are not mandatory unless specifically referenced in the adopting ordinance.
User notes:


About this appendix: This appendix addresses the considerations that need to be taken into account by building officials regarding the placement and installation of nonsewered santiation systems in buildings. This appendix would permit the installation of a of these systems and provide an exception to the general requirement in the International Plumbing Code and this code that sanitation devices be connected to the building drainage system.

CG101​

INSIGHTS (3)

CG101.1​

The provisions of this chapter shall apply to the installation of nonsewered sanitation systems.
INSIGHTS (2)

CG101.2​

Nonsewered sanitation systems shall comply with ANSI/CAN/IAPMO/ISO CG106.1.
Excellent, thanks
 


 
Maybe CPC 411.2? It says that "all water closets" shall have a certain flush volume, implying that the toilet needs to be a flushing type.

411.2 Water Consumption
The effective flush volume of all water closets shall not exceed 1.28 gallons (4.8 L) per flush when tested in accordance with ASME A112.19.2/CSA B45.1.

Edit: Oh, sorry, saw "CA" as your location and immediately assumed CPC / UPC. My bad... In IPC, I believe the section you're looking for is 425 or 604.4.
Regarding California, the way 411.2 is worded, a no-water outhouse (zero gallons per flush) would comply with the requirement to not exceed 1.28 gallons per flush.
 
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