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  • Ken Loucks

2021 NSPC Code Hearing Update

The National Standard Plumbing Code (NSPC) held its Public Hearing on July 11, 2019 to review the Proposed Code Changes for the 2021 edition of the code. Changes approved at this hearing will appear in the 2021 NSPC. I submitted three code change proposals and opposed two others successfully. Here is a summary of the relevant proposals and the votes of the committee:


Donald Jones (Summit, NJ), Julius Ballanco, P.E. (Munster, IN), and Dan O’Gorman (Edison, NJ) address the NSPC Committee as they review proposed code changes towards the development of the 2021 National Standard Plumbing Code.

Item #21-23

6.2.1.1 subsection c. A calibrated, non-adjustable flow control device shall be provided on the inlet side of each HGI interceptor to prevent the waste flow (gpm) from exceeding the rated flow capacity of the interceptor. The flow control device shall be vented in accordance with Section 6.2.4. Exception: Listed HGI interceptors with integral flow controls or restricting devices shall be installed in an accessible location in accordance with the manufacturer’s installation instructions.


Basis/Reason for Change: There are certified and listed grease interceptors that have unvented integral flow controls that are built into inlet fittings inside of the grease interceptors. This exception is necessary to approve HGIs with integral flow controls. Both the Uniform Plumbing Code and the International Plumbing Code allow certified and listed HGIs with unvented integral flow controls. This code change proposal adds an exception that allows for integral flow controls.


Committee Vote: Approve


Item #21-24

Basis/Reason for Change: Grease interceptors are not fixture traps. A trap is defined in the code as, “a fitting or device that provides a liquid seal to prevent the emission of sewer gasses without materially affecting the flow of sewage or wastewater through it.” Many modern grease interceptors have open top or vented inlet fittings that do not provide a liquid seal. This has and will lead to dangerous exposure to airborne pathogens and noxious odors inside buildings. This code change proposal deletes the exception that allows a grease interceptor to serve as a fixture trap.


Committee Vote: Approve


Item #21-25

Figure 6.2 B

This drawing is included in the code in support of using a grease interceptor as a fixture trap for a single fixture. This code change proposal deletes this drawing from the code.


Committee Vote: vote not necessary, delete editorially. Withdrawn by proponent.


Item #21-26

Basis/Reason for Change: The Uniform Plumbing Code and International Plumbing Code do not permit food waste disposers to discharge into grease interceptors. The discharge from food waste disposers is more than grease. GGI gravity grease interceptors are designed to retain large amounts of solids.


The proponent of the next code change proposal (21-27) argued that this code change should be rejected by the committee in favor of the code change proposal in 21-27. I testified in support of REJECTING this code change proposal as well, but not because I support the next code change proposal.


Committee Vote: Disapprove


Item #21-27

Basis/Reason for Change: The food waste disposer industry and the grease interceptor industry recognize that a food waste disposer should never discharge through a grease interceptor. The food particles will cause the grease interceptor to go septic. Even with a solids interceptor, food particles will pass through since the solids interceptor is not fine enough to remove all of the food particles. The allowances in the current code is a poor practice. The other model plumbing codes have added a prohibition on the discharge of food waste disposers through a grease interceptor.


The proponent of this code change argued in testimony that there is more fats, oils and grease (FOG) in human feces than in food waste discharged through a food waste disposal.


I testified in opposition of this code change because there is actually overwhelming amounts of FOG discharged through food waste disposers. I informed the committee that my clients are the pretreatment programs that have to live with code change issues such as this and that when plumbing codes allow food waste disposers to connect directly to the sanitary system they create severe problems in wastewater collection systems.


Committee Vote: Disapprove


If you want to know more about the consequences of connecting food waste disposers directly to sanitary, check out these two blog posts I previously wrote:




The code changes that I proposed and that were approved, will create more opportunity for manufacturers to innovate and provide better solutions in grease interceptor designs.


The code changes regarding food waste disposers that would have allowed them to discharge directly to sanitary would have created significant problems for wastewater collection systems and increased costs for maintenance for pretreatment programs. In rejecting these changes in favor of the language that had been in the code already, the committee helped to protect the wastewater collection systems that would have been negatively impacted.


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