Kitchen Sink Clogged? Discover What's Causing the Backup

A clogged kitchen sink is one of the most annoying household plumbing issues. You're cleaning up after dinner when you notice the water is draining slower than usual. Next thing you know, the sink is filled with cloudy water that refuses to go down the drain. Ugh, not again!

Dealing with a backed up and smelly kitchen sink is no one's idea of a good time. But before you resort to chemical drain cleaners that damage pipes or pay a plumber for an expensive house call, it helps to understand what causes these pesky clogs in the first place. Read on to discover the most common culprits of kitchen sink backups so you can get to the root of the problem and get your sink draining freely again.

Grease Buildup

Grease is public enemy number one when it comes to clogged drains. As greasy foods like bacon, sausage, and fried foods go down the sink, grease sticks to the inside of the pipes. Over time, layer upon layer of grease accumulates. Eventually, this greasy gunk completely blocks water flow through the pipes.

Grease may start as a slippery liquid, but as it cools it solidifies into a thick substance that clings tenaciously to pipe walls. Attempting to wash grease down with hot water often makes the situation worse. The heat melts the grease which travels further down the pipes until it cools and hardens again into a more stubborn blockage.

The most grease-laden kitchen sink offenders include:

• Meat fats from bacon, hamburger, chicken skin
• Butter and margarine
• Lard and shortening
• Cooking oil
• Dairy products like sour cream and cream cheese
• Gravy and pan drippings from roasted meats
• Salad dressings and mayonnaise
• Creamy sauces and pasta dishes

Preventing Grease Clogs

The best way to avoid a grease clog is to keep as much grease as possible out of the kitchen sink in the first place. Here are some tips to minimize grease going down the drain:

• Pour cooled cooking grease into an empty can or jar for disposal rather than washing it down the sink. The grease will harden as it cools and you can throw it away.
• Use paper towels to wipe pots, pans, and dishes to remove greasy residues before washing. Throw away the greasy paper towels.
• Scrape plates with a rubber spatula before rinsing to remove leftover fats and oils.
• Avoid using the garbage disposal for greasy food scraps. Compost them instead if possible.
• Run very hot water when pouring greasy liquids like pan drippings down the drain. The heat will liquefy the grease and prevent buildup.
• Clean with grease-fighting dish soap or detergent to help emulsify oils.

Food Particles

Crusty bits of food leftover from washing dishes may seem harmless as they wash down the sink drain. However, over time, accumulated food particles can cling to pipe walls and clog drains.

Carbohydrate-rich foods like rice, pasta, oatmeal, and potatoes readily break down when wet. The starchy mush sticks to pipes and combines with fats to create thick buildup. Chunks of food like eggshells, seeds, dried beans, and pulp from fruits and veggies can also accumulate into obstructions.

Hair, grease, and grime already lining the pipes latch onto food particles passing by. Gradually, bits of food debris, grease, and other gunk coat the inside of the pipes, progressively narrowing the drainage opening. Eventually, the pipes become entirely clogged.

Stop Food Debris From Clogging Drains

Using sink strainers can catch stray food scraps during cleanup and prevent them from clogging drainpipes. Take these additional precautions to keep food particles from gradually obstructing your drains:

• Scrape dishes well before washing to remove stuck-on food.
• Avoid pouring loose grains like rice directly in the sink drain. Dispose of excess in the trash.
• Grind up scraps using a garbage disposal if you have one installed.
• Compost vegetable peels, eggshells, and other food waste rather than sending down the drain.
• Remove the sink strainer and clean it regularly to remove lodged debris.
• Use enzyme drain cleaners monthly to digest accumulated organic matter.

Soap Scum Buildup

The fats and minerals present in dish and sink cleaning soaps can leave behind a filmy, sticky residue known as soap scum. This grimy film clings to pipes, slowly narrowing drainage pathways.

The minerals calcium and magnesium react with the fatty acids in soap to form an insoluble film. Soap scum tends to accumulate more readily in hard water, which is high in minerals.

As bits of organic matter stick to soap scum in the drain, it thickens into a stubborn gunk. Bacteria and mold feeds on the residue, developing into a thick slime layer that clogs drains and even pipes under the sink.

Minimizing Soap Scum

To prevent soap scum buildup on sink drains:

• Choose liquid hand and dish soaps formulated for hard water if applicable.
• Avoid bar soaps which contain more fatty acids.
• Let hot water run for a few minutes after washing dishes or cleaning the sink to rinse away soap film.
• Clean the sink basin regularly with a grease-cutting cleaner to remove residue.
• Use a sink strainer to catch food particles that could stick to soap scum.
• Periodically flush drains with baking soda and vinegar to dissolve scum.

Hair Clogs

That tangled mass of hair you pull from the shower drain is harmless enough until it washes down into your kitchen pipes. Strands of hair shed naturally can quickly accumulate into clogs within narrow pipes.

Making matters worse, conditioners and other hair products cause loose hair to become gloopy and sticky. The hair products cling to pipes while locks of hair weave together, forming impenetrable obstructions.

Since showers are often located above kitchen sinks, it's easy for wet hair to travel down pipes into the kitchen drain. Hair clogs tend to form suddenly, starting with a few stray strands that eventually multiply into a dense knot.

Preventing Hair Clogs

To keep shed hair from clogging up kitchen drains:

• Install hair catchers in shower and sink drains to trap strands before they wash down.
• Brush and rinse hair before showering to remove loose strands that could come out in the shower.
• Clean hair from the shower drain regularly by removing the catch and pulling out accumulated hair.
• Use a drain cover/stopper when washing hair in bathroom sinks.
• Avoid letting hair fall into the kitchen sink by tying it back or using a cover when at the sink.

Clogged Garbage Disposal

If your kitchen has a garbage disposal, it can actually protect drains by grinding up food waste into tiny particles. However, even garbage disposals can become clogged by the wrong materials.

Fibrous foods like celery, artichokes, and corn husks can jam the blades. Coffee grounds, eggshells, and potato peels accumulate to block the disposal. Bones, grease, expandable foods like rice and pasta, and even silverware can bring the grinding mechanism to a halt.

When the disposal stops working properly, food particles, dirty water, and even sewage can back up from the clogged unit into the sink or other drains. The sink may fill with murky water or make loud straining noises as the jammed disposal struggles to operate.

Garbage Disposal Best Practices

Follow these tips for smooth garbage disposal operation:

• Run plenty of cold water when grinding food waste to flush particles down the drain.
• Avoid putting hard or fibrous foods down the disposal.
• Grind citrus peels sparingly, as the oils can gum up the works.
• Run the disposal before and after food prep to clear pipes.
• Freshen it monthly by grinding ice cubes or frozen vinegar cubes.
• Regularly remove and clean the splash guard to prevent buildup.

Clogged or Damaged P-Trap

The curved pipe fitting underneath kitchen sinks and other drains is called a P-trap. True to its name, this trap is designed to hold a small amount of water to prevent sewer gases from entering living spaces.

Over time, debris, hair, and gunk passing through the drain get caught in the P-trap. If the clogged P-trap becomes completely blocked, water can no longer drain properly from the sink. A damaged or improperly installed P-trap can also impede drainage.

P-Trap Maintenance

To prevent P-trap clogs:

• Detach the P-trap and clean it thoroughly every 3-6 months. Use a bottle brush to clear interior debris.
• Check for cracks or damage when cleaning. Replace if necessary.
• When reattaching the P-trap, ensure all fittings are secure and properly aligned to maintain the water seal.
• Consider replacing metal P-traps with plastic models, which resist buildup.

Clogged Vent Stack

The vent stack or vent pipe is designed to allow air to enter the plumbing drainage system. This enables water to drain freely down pipes. If airflow is blocked, water struggles to drain resulting in gurgling sinks, slow drainage, and backups.

The opening to the vent stack is typically found on the roof. Debris like leaves or tennis balls can fall in and obstruct it. More problematic are internal obstructions deeper in the vent stack. Years of buildup or complete pipe blockage prevents proper venting.

Signs of a clogged vent stack include gurgling noises from drains, the need to plunge frequently, fixtures draining slowly, and bad sewer smells even when traps contain water.

Clearing Clogged Vents

Here are some ways to address a clogged vent stack:

• Climb on the roof and clear any debris from the vent opening. Install a vent screen to prevent future debris entry.
• A professional plumber can snake the vent stack to remove stubborn obstructions.
• High pressure water jetting is sometimes used to blast away years of accumulated buildup inside vents.
• If the vent stack is severely damaged, it may need to be replaced entirely.

Main Sewer Clog

Kitchen drains connect to main sewer lines that carry wastewater out of the home. An obstruction in this main sewer line can back wastewater up into fixtures, including kitchen sinks.

Main sewer clogs are often caused by invasion of tree roots. If pipes are damaged or have cracks, tree roots penetrate seeking water. The roots grow over time, forming a dense mat that plugs the line.

Other common main sewer clog culprits include grease and soap buildup, broken pipes causing debris accumulation, sagging pipes, and even foreign objects like toys flushed down toilets.

Preventing Main Sewer Clogs

Here are some tips to reduce the likelihood of main line clogs:

• Plant trees away from sewer lines and inspect for root intrusion.
• Schedule professional sewer line cleaning every 1-2 years to clear grease and debris before it accumulates.
• Avoid pouring fats down drains and use enzyme cleaners to break down organics.
• Fix any cracks in sewer pipes promptly to prevent root intrusion or debris entry.
• Replace old clay or damaged sewer lines with smooth PVC piping.

As you can see, kitchen sink clogs can stem from an array of causes. By understanding the most common culprits, you can take steps to prevent backups before they happen.

Regular maintenance like drain cleaning and garbage disposal use can keep pipes clear. Adjusting cooking and cleanup habits to minimize grease and food waste down drains is also key.

Catching clogs early and attempting DIY unclogging methods like plunging often resolves issues quickly. But if you have recurring clogs or water continues backing up, it may be time to call a professional plumber to inspect for and clear blockages.

Now that you know what's likely causing your clogged kitchen sink, you can get to work restoring full water flow and getting your sink back to draining properly again.