Seasonal · Published 2026-08-09
The plumbing trade has a name for the day after Thanksgiving, and it is not a flattering one. Roto-Rooter reports that service calls run about 50% above average that day, and roughly 21% above average across the whole four-day weekend. It is the most predictable failure in residential plumbing, and almost all of it comes down to one thing.
The mechanism, in one paragraph
Turkey fat, gravy, butter and the oil from roasting go down the sink as a warm liquid. Within a few feet of the trap they cool below their melting point and deposit on the pipe wall. On their own, over a normal week, that deposit is manageable. Over a Thanksgiving weekend — a full house, three or four times the usual dishwashing, and a bird that rendered most of a cup of fat — the deposit goes on faster than the line can carry it away. Then someone puts potato peel or rice down after it, and the starch binds to the fat, and the line stops.
It is not that anyone did anything unusual. It is that everyone did the usual thing at four times the usual rate, in a two-day window.
What actually goes wrong, in order
- Wednesday and Thursday: fat accumulates in the kitchen branch line faster than normal flow can move it.
- Thursday evening: starchy waste — potato peel, stuffing, rice — goes down after the fat and binds to it.
- Friday morning: the first big dishwasher load hits a line whose effective diameter has halved. The sink backs up.
- Friday afternoon: the whole country calls a plumber at once, on a public holiday, at holiday rates.
The garbage disposal will not save you
This is the single most common misunderstanding, and it is worth being blunt about. A disposal grinds food. It does not dissolve it. Everything you put through it still has to travel down the same pipe, just in smaller pieces — and smaller pieces bind together more readily with fat, not less.
Running cold water while grinding genuinely helps, because it keeps fat solid so it is carried away rather than melting and coating the pipe further along. Running hot water does the opposite. That is the reverse of what most people assume.
What to actually do
- Fat goes in a container, then the bin. Let it cool first. This one habit removes most of the risk.
- Scrape plates into the bin before they reach the sink. Not the disposal — the bin.
- No rice, pasta, potato peel, celery, corn husk or coffee grounds down the disposal. Starchy and fibrous waste is the other half of the problem.
- Cold water while grinding, and keep it running twenty seconds after.
- Space out the dishwasher loads. Four loads back to back is a surge test on a line you have just loaded with fat.
- If the kitchen sink has been slow for weeks, deal with it in early November. A line that is already restricted is the one that fails on the Friday.
If it happens anyway
Stop running water into that sink — every extra litre makes the standing water deeper without moving the blockage. Do not reach for a chemical cleaner: these are formulated for hair and soap, not congealed fat, and it will sit in the standing water doing nothing while making the eventual repair unpleasant for whoever opens the trap.
If both basins are full, or water comes back up in the other side, the blockage is past the point where they join and it is a branch-line job. What a kitchen sink blockage actually involves →
Why the number is real
The 50% figure comes from Roto-Rooter, which is the largest operator in the sector and has the call volume to see the pattern clearly. It is worth noting they have a commercial interest in the story — but the mechanism is straightforward physics, the pattern is reported consistently year on year, and every plumber who has worked a Thanksgiving weekend will tell you the same thing without being asked.
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