How a grease clog builds
Fats, oils and grease leave the pan warm and liquid. Within a few feet of the sink they cool, turn tacky and cling to the pipe wall. Each rinse adds a thin layer, and starch from pasta water, rice and potato peels gives the coating body. Coffee grounds and bits of food lodge in it like gravel in mortar.
The opening narrows slowly, so the first sign is usually a sink that takes a few extra seconds to empty. The full stop tends to come after a big cooking day, when a large load of grease and rinse water arrives at once and finally bridges the gap.
Hot water and dish soap move grease along but do not dissolve it for good. The grease simply travels farther down the line before it cools and settles again, which is why a clog can sit in the wall or under the slab rather than right below the sink.
Grease clogs at a glance
- Usual location
- Trap arm and the first several feet of the kitchen branch line
- Early sign
- Slow draining with the disposal off
- Common trigger
- Holiday meals, roasting pans, deep frying
- Typical fix
- Drain cable, or water jetting for heavy buildup
- Avoid
- Caustic or acid drain openers
Cable versus jetting on a grease clog
Both are common. The right choice depends on how much grease coats the line and the pipe's age and condition.
| Drain cable (auger) | Water jetting |
|---|---|
| Breaks through the blockage and restores flow quickly | Scours grease off the pipe walls along the run |
| Works well on a short plug near the trap | Suits lines that clog again and again |
| May leave grease coating the pipe walls | Pipe material and condition need to be checked first |
| A grease line cleared only by cable can close up again | Usually needs an access point such as a cleanout |
Keeping grease out of the drain
- Let pan grease cool and solidify, then scrape it into the trash.
- Wipe greasy pans and plates with a paper towel before washing.
- Pour used frying oil into a sealed container for disposal; check with the city about local options for fats, oils and grease.
- Keep coffee grounds and eggshells out of the sink and disposal.
- Use a basket strainer to catch rice, peels and food scraps.
- Run plenty of cold water while the disposal grinds and for a few seconds after.
What to ask the plumber about a grease clog
- Where in the line do you think the grease is sitting, and why?
- Will you use a cable, jetting or both, and what cutting head suits my pipe?
- If it clogs again in a few months, what would you recommend next?
- Can you show me the grease you pull out so I know what we are dealing with?
Common questions
Does pouring boiling water down the drain melt a grease clog?
It can loosen a small amount near the sink, but the grease cools and resettles farther down the line. Very hot water can also stress some plastic fittings. It is not a fix for a line that has stopped.
Are enzyme or bacteria drain products useful?
Some people use them as slow maintenance on a line that still drains. They will not open a sink that has stopped, and they do not replace keeping grease out of the drain.
Why does the clog come back after a plumber clears it?
A cable often punches a hole through the grease without removing the coating on the walls. Repeat clogs are a reason to ask about jetting or a camera inspection of the line.
General information for Fullerton, not a quote or professional advice. In an emergency, call 911.