How do I avoid drain clogs after a big holiday meal?

Grease is the main cause. City of Phoenix Water Services says "The biggest problem is coagulated grease and cooking oil," and explains that people pour warm grease down the drain thinking it will flow. But "the cooking oil and grease will cool as it enters the sewer line and it will coagulate, causing a blockage, in much the same way cholesterol blocks arteries in humans." EPA's sewer overflow guidance lists the other usual suspect: "materials such as fats, oils and grease (FOG), and some household products (including some marked 'flushable') such as baby wipes, facial wipes, sanitary pads, and tampons."

A holiday adds volume to that. Pan drippings, gravy, roasting-pan soak water and a sink full of scraped plates arrive all at once, and a drain that was already marginal tips over.

• Test the slow drains. Run the kitchen sink, tub and shower and watch for gurgling or sluggish draining. Slow now means stopped on the big day. See why the same drain keeps clogging and kitchen sink keeps clogging.
• Find your sewer cleanout. If something backs up, the cleanout is how a plumber reaches the line, and it is also the first place to look. What a sewer cleanout is shows what to look for.
• Fix the running toilet. EPA notes a single leaky or running toilet "can add as much as 200 gallons of water per day," which matters if you are on septic. How to fix a running toilet.
• If a drain is already slow, call before the holiday. HQ Plumbing and Air answers 24/7, but a Wednesday visit is easier on everyone than a Thanksgiving-night backup.

• Grease: do what Phoenix says. "Allow the grease or cooking oil to cool in the cookware that was used, and then scrape it into the trash can." Wipe greasy pans with a paper towel before they reach the sink. Hot water does not solve it, because the point of Phoenix's warning is that grease cools and sets once it is in the pipe.
• Plates: scrape into the trash or compost, not into the sink. Rice, pasta, potato peels and fibrous scraps are the foods that jam a disposal; our page on what not to put in the garbage disposal at the holidays has the full list.
• Disposal: if you are on septic, EPA says to "eliminate or limit the use of a garbage disposal," since it "will significantly reduce the amount of fats, grease, and solids that enter your septic tank."
• No chemical drain cleaner as a safeguard. It does not prevent a clog and can damage pipes; see why to avoid chemical drain cleaners.

Put a small lidded trash can next to the toilet and say what goes in it. EPA's septic guidance is a short rule for every household: "An easy rule of thumb is not to flush anything besides human waste and toilet paper." That means no wipes, even ones marked flushable (flushable wipes explained), no paper towels and no feminine products. Guests do not know your plumbing. A sign or a conversation helps more than hoping.

Some homes in the Valley are on septic, not city sewer; how to tell whether you have septic or city sewer explains how to check. EPA warns that "Doing all household laundry in one day might seem like a time-saver but it can harm your septic system. It will not allow your septic tank enough time to treat waste and could flood your drainfield." For a crowded weekend, wash towels and linens in the days before and after, not during, and stagger dishwasher runs.

1. 1Stop adding water: no flushing, no sinks, no washer or dishwasher.
2. 2If sewage is coming up in a tub or floor drain, keep people and pets away.
3. 3Check whether it is one fixture or the whole house. Main line vs branch clog shows how to tell.
4. 4Skip chemical drain cleaner. A plunger or a hand auger works on a single sink; anything that affects more than one fixture is a main-line problem.
5. 5Call a licensed plumber. HQ Plumbing and Air handles drain cleaning and emergency calls, with an upfront price before the work starts.