top of page

Plumbing Codes vs. Pretreatment Policy

One of the biggest challenges in the evolving world of grease interceptors is understanding the roles of plumbing codes and pretreatment ordinances. The plumbing code and its inspectors are the watchman over the plumbing systems in commercial and residential building construction. The pretreatment ordinance and its inspectors are the watchman over the wastewater collection system. In the vast majority of jurisdictions in the US the pretreatment ordinance supersedes the plumbing code in authority, where a conflict between the two exists.

When it comes to grease interceptors the plumbing code has been mandating their use and governing their approvals since 1946, whereas pretreatment authorities have only more recently gotten involved with them. This has created an interesting dilemma; pretreatment ordinances are concerned with the quality of the wastewater entering the collection system while plumbing codes are concerned with setting a minimum standard for the construction of a plumbing system. Plumbing codes are not intended to ensure that the wastewater discharged by a point source polluter is compliant with pretreatment policy. Events leading up to the amendments to the 2011 Oregon Plumbing Specialty Code (OPSC) (effective January 1, 2013) illustrate this disconnect.

Let’s say you are a municipality in Oregon operating under an NPDES permit issued by the EPA mandating you to implement a program to reduce sanitary and combined sewer overflows in your jurisdiction. Let’s say you go out into your community and begin inspecting restaurants to see what they are doing to mitigate the discharge of fats, oils and grease to your collection system. Let’s say you discover they have a lot of grease build-up in the laterals leading to your collection system. Let’s say you discover that a significant number of these facilities either have no grease interceptor or have an undersized interceptor serving their multi-compartment sink and they are not maintaining it very well or very often. Let’s say you also discover a significant amount of grease discharging through fixtures that are not even connected to the grease interceptor.

Now, let’s say you talk to the plumbing plans review and permitting department and they tell you that they just, "follow the state plumbing code." In reading the state plumbing code you discover the following language, "Where it is determined by the Authority Having Jurisdiction (you, in this story) that waste pretreatment is required, an approved type of grease interceptor(s) complying with the provisions of this section shall be correctly sized and properly installed in grease waste line(s) leading from sinks and drains...where grease is introduced into the drainage or sewage system in quantities that can effect line stoppage or hinder sewage treatment..."

That language is pretty vague so let’s say you tell the plans reviewer and permit issuer that you want them to require all fixtures in a commercial kitchen be routed to a grease interceptor. What happens if they don't agree with you (because they haven't investigated the discharge of fats, oils and grease from these kinds of facilities and aren't aware of the problem you are trying to address).

This would be the point at which you learn that, in Oregon, you don't have the authority to make such a requirement because of this little clause in ORS Chapter 455 Building Code, Section 455.040, "The state building code shall be applicable and uniform throughout this state and in all municipalities, and no municipality shall enact or enforce any ordinance, rule or regulation relating to the same matters encompassed by the state building code but which provides different requirements unless authorized by the Director of the Department of Consumer and Business Services."

This is very much what happened in Oregon.

Fortunately, stakeholders were able to sit down and discuss the problem which ultimately led to an amendment to the state plumbing code that now reads, "Waste pretreatment is required in all Food Service Establishments...The following plumbing fixtures and drains shall be connected to the grease interceptor(s): All plumbing fixtures, garbage disposals, dish-washers, floor drains, and cooking equipment, with drain connections in food and / or beverage preparation areas of all Food Service Establishments."

This amendment was only possible because plumbing code officials were open to the idea that the plumbing code should support pretreatment program compliance requirements. Of course, ultimately this needs to be done nationally which will require amending plumbing codes such as the Uniform Plumbing Code, the International Plumbing Code as well as the various state plumbing codes to make them more effective and supportive of pretreatment programs. Effective FOG abatement requires a team effort that includes comprehensive pretreatment ordinances supported by effective plumbing codes.

Oregon provides a case-in-point regarding the disconnect that often exists between plumbing codes and pretreatment program compliance requirements, but also a model for resolution that benefits everyone.

570 views0 comments

Recent Posts

See All


bottom of page