Why coconut oil hardens in the pipe
Coconut oil melts at a temperature just below normal room temperature. That means it stays liquid while it is hot from the pan, then cools as it travels down the drain and sets into a waxy solid on the pipe wall. The cold water running with it hastens that.
Once a thin layer sets, soap residue, coffee grounds and food bits stick to it. The opening narrows slowly. The first sign is usually a slower drain, followed by a total stoppage on a day you have a lot of dishes.
The International Plumbing Code (IPC) requires grease interceptors in many commercial kitchens, which tells you how seriously the code treats fats in drains.
How common fats behave in a drain
| Fat | At room temperature | In the drain |
|---|---|---|
| Coconut oil | Solid or semi-solid | Hardens and coats the pipe |
| Bacon grease | Solid | Hardens quickly |
| Butter | Solid | Collects with other residue |
| Vegetable oil | Liquid | Still sticks with soap and food, and can congeal |
| Olive oil | Liquid | Same, in time |
What to do with used coconut oil
Let it cool and solidify in the pan or a jar. Scrape it into a sealed container or a container with a lid and put it in the trash. Wipe pans with a paper towel before washing. For liquid oils, keep an empty can or jar by the stove and pour the oil in as it cools.
A garbage disposal does not solve this. It grinds food but not grease, and it pushes the fat into the pipe where it cools. See garbage disposal repair if the disposal is also giving trouble.
What helps and what does not
Hot water from the tap can melt a fresh grease layer near the drain opening, which is a sensible first step. It will not reach a coating several feet down. Dish soap added to hot water helps a little. Chemical cleaners are a poor choice, since they can damage pipes and make later service hazardous.
If the sink drains slowly, try a plunger or a drain stick first. Repeated slow drains mean the coating is still there, and that is the time to call.
How a plumber removes a grease clog
A cable machine can punch through a grease plug, but the coating remains and the clog returns. Hydro jetting scours the pipe wall with high pressure water and carries the grease out. Our hydro jetting page explains when it fits and when a camera look should come first.
If a line has been clogged by grease more than once, a camera shows whether the pipe has other problems, such as a sag where grease collects.
Households and small food businesses
Home cooks are not the only ones who face this. Small restaurants and food trucks in town fry food and wash pans in sinks that connect to the same sewer. A grease interceptor and scheduled cleaning keep the line moving. See commercial plumbing for what a food business should plan for.
The habit is the same at any scale. Wipe pans before washing, never pour fat down a drain and schedule service before a busy season.
Other things that behave the same way
Coconut oil is not alone. Butter, shortening, lard, bacon grease and even melted candle wax behave the same way in a pipe. So does the grease that washes off pans with hot soapy water. The soap makes the fat travel further, and then the fat separates and sticks when the water cools.
Dairy products, rice and pasta water add starch, which gives the coating something to hold on to. Coffee grounds do not dissolve and collect on the coating. A drain that gets all of these is a drain that will eventually need a cleaning, however careful the household is.
How often a busy kitchen needs service
A household that cooks often with fats may want a cleaning every year or two even without symptoms. A restaurant needs more regular service, often set by the volume of cooking. The point of a schedule is to remove the coating before it becomes a plug.
Ask the plumber about a camera look after a jetting visit. It shows how clean the pipe is and whether any low spot is collecting grease. See sewer camera inspection for what that involves.
Grease and the El Reno sewer
Grease clogs affect private lines and the city's own sewer mains. The City of El Reno public works office at 405-262-4070 can answer questions about reporting a problem in the public line, and the city's code addresses how building sewers connect to the public sewer. A backwater valve is required on a building sewer that connects to it, and a grease-clogged line can make that valve hold open.
If you live in Yukon or Piedmont, the same habits apply, and your city has its own contacts.
Source type: City public works and local code
Questions El Reno homeowners ask
A very small amount mixed with hot water may pass, but repeated use builds a coating. The safe habit is not to pour it.
It melts it near the opening, but the oil can cool and set again further down the line.
They may loosen a light film, but they do not remove a thick coating. See our other guides for details.
Slow kitchen sink drains that get worse over weeks, with a greasy smell, suggest grease.
Our line is open 24/7, and a licensed plumber is scheduled the same day when one is available.