T.K. Livingston said his Thanksgivings are sometimes interrupted by a customer call.
Livingston is owner of Affordable Same Day Service, a plumbing and appliance business in Columbia. He and other Columbia plumbers said the kitchen sink garbage disposal is usually the problem. The calls had already begun on Tuesday. After the interview, he was off to replace a ruined garbage disposal.
"A lot of time people throw egg shells, potato peels, carrot peels down their disposals," Livingston said. He said older homes have smaller pipes that can't handle the material.
He said if a kitchen sink gets clogged, it also will cause the dishwasher to become backed up.
"We always get drain calls," said Brian Wear, owner of Brian Wear Plumbing. "Typically it's just disposals. People stuff too much stuff down the disposal."
He said if there's an underlying problem that doesn't occur with a small family in a home it can surface when a big crowd comes to visit.
"A customer last year had 30 people over for Thanksgiving," Wear said.
He said even if the disposal usually works well, people should dispose of food scraps in the garbage on Thanksgiving and when disposing of leftovers in the days after.
"Peels and egg shells are a bad idea, even through the disposal," Wear said. "They stick in the pipe."
Dale Cornine, owner of Wallace Plumbing, said when many visitors are in a home at the same time, the kitchen sink gets clogged when the disposal is overworked. He said if people use their disposals, they should use lots of water to wash it down.
Cornine and the other plumbers also said grease can clog the pipes.
Livingston said the grease can build up in home water lines over a period of years, eventually causing a backup.
Wear said food grease and even shampoos and conditioners can cause pipes to clog. He recommends to customers a product that uses bacteria to consume the oil and grease in home pipes to keep them clear.
All three said chemical drain cleaners should always be avoided. Cornine said it breaks down metal pipes and cause chemical burns to the user.
"Now I've got to deal with harsh chemicals," Livingston said. "It's a corrosive issue that can causes serious burns. In newer homes, I've seen the PVC piping melt."
Livingston said when chemicals are used, the repairs usually are much more costly because more needs to be replaced.
The food waste doesn't burden the Columbia wastewater treatment plant, because it's built to handle large volumes of waste, said Patricia Weisenfelder, a city spokeswoman.
Erin Keys, engineering and operations manager for Columbia sewer and storm water utilities, said there is less volume of waste during Thanksgiving in Columbia because most students have left town.
She said cooking grease does cause buildup in wastewater mains, so regular maintenance is required to clean them out.
"We have a few we clean out every six months," Keys said. "People should not put oil and grease down their drains."
When food waste and grease reaches the wastewater treatment plant, it eventually is processed in an anaerobic digester, which uses bacteria and creates methane gas as a byproduct. The methane is used to heat the building and the digester, Keys said. When processed, the solids are applied to farm fields.