Why Your Drains Keep Clogging and What to Do About It

A drain that clogs once is an inconvenience. A drain that clogs repeatedly is telling you something — and the answer is almost never that you need a stronger bottle of drain cleaner. Recurring clogs are a symptom of a deeper issue in your plumbing system, and treating only the symptom means the problem keeps coming back.

Grease Buildup in Kitchen Lines

The most common cause of recurring kitchen drain clogs is accumulated grease. Even small amounts of cooking oil, butter, and food grease coat the inside of drain pipes over time. The grease cools and hardens on the pipe walls, gradually narrowing the opening and trapping food particles, soap residue, and other debris.

Pouring hot water or using chemical drain cleaners provides temporary relief by softening the grease enough for water to pass, but the buildup remains on the pipe walls and re-hardens. Each time, the effective diameter of the pipe gets a little smaller. Professional drain cleaning with a motorized cable or hydro jetting removes the buildup from the pipe walls, restoring full flow.

Hair and Soap Scum in Bathroom Drains

Bathroom drains — especially showers and tub drains — accumulate hair, soap residue, and skin oils that bind together into stubborn blockages. Hair wraps around the drain cross-bars and snags in pipe joints, creating a net that catches everything else flowing through.

Drain screens are the most effective prevention. A simple mesh screen over the shower drain catches hair before it enters the pipe. For drains that are already slow, professional snaking removes the accumulated mass without risking the pipe damage that chemical products can cause, especially in older homes with corroded fittings.

Tree Root Intrusion in Sewer Lines

If multiple drains in your home are slow simultaneously, or if your main sewer line backs up periodically, tree roots may be growing into your sewer lateral. Roots are naturally attracted to the moisture and nutrients inside sewer pipes and can enter through tiny cracks or loose joints in older clay or cast iron laterals.

Once inside, roots expand and create a dam that catches waste, toilet paper, and debris. Clearing roots with a cable machine provides temporary relief, but the roots grow back. For a lasting solution, a sewer camera inspection identifies the entry points and condition of the pipe, and repair options range from targeted root barriers to trenchless pipe relining.

Damaged or Deteriorating Pipes

Older pipes — especially cast iron drain lines and clay sewer laterals common in San Carlos homes built before the 1970s — develop internal rough spots, cracks, and misaligned joints as they age. These imperfections catch debris and create recurring blockage points.

If professional drain cleaning solves the problem but it returns within a few months at the same location, the pipe itself may be the issue. A camera inspection can reveal the condition of the pipe and determine whether repair, relining, or replacement is needed.

Why Chemical Drain Cleaners Make Things Worse

Store-bought chemical drain cleaners work by generating heat and dissolving organic material. While they can open a temporary channel through a clog, they also corrode metal pipes, weaken PVC joints, and damage the protective lining inside cast iron drains. Repeated use accelerates pipe deterioration and can turn a clog problem into a pipe replacement problem.

They are also ineffective against the most common causes of recurring clogs — grease buildup on pipe walls, tree roots, and pipe damage. For recurring drain issues, professional cleaning with appropriate tools is both safer for your pipes and more effective at addressing the root cause.