Drain Keeps Clogging? Here’s What’s Really Going On

A drain that keeps clogging is trying to tell you something.

The difference matters — because the fix for a recurring clog is almost never the same as the fix for a one-time blockage. Pouring drain cleaner down a slow sink might buy you a few weeks. But if the underlying cause isn’t addressed, you’ll be back in the same spot before long, and in some cases the problem will be worse.

Here’s what’s actually behind recurring drain clogs — and what each pattern usually means.

Not All Drains Clog for the Same Reason

The most useful thing to understand about a recurring drain problem is that location matters enormously. A kitchen sink that clogs repeatedly has a completely different root cause than a basement floor drain that backs up during heavy rain. Treating them the same way is how homeowners end up frustrated and spending money on fixes that don’t stick.

Kitchen Sinks: Almost Always Grease and Buildup

Kitchen sink clogs are the most common drain complaint we hear — and the cause is almost always the same: grease, fat, and food particles that accumulate inside the drain line over time.

Even small amounts of cooking grease that are rinsed down the drain with hot water will cool and solidify further down the pipe, narrowing the drain line gradually until flow slows to a trickle. Soap scum and food debris layer on top of that buildup, and the cycle compounds.

What makes kitchen clogs recurring is that a partial blockage — one that slows drainage without stopping it entirely — is easy to ignore until it becomes a full stoppage. By the time the drain is completely blocked, there’s often significant buildup deeper in the line than a standard drain snake can reach.

The honest advice: don’t put grease down the drain, ever. Let it cool and dispose of it in the trash. It sounds simple because it is — but it’s the single most effective way to prevent kitchen drain problems.

Bathroom Drains: Hair, Soap Scum, and Toothpaste

Bathroom sink and shower drain clogs follow a predictable pattern. Hair binds to soap residue inside the drain, creating a net that catches everything else. Over time that accumulation grows until drainage slows or stops completely.

These clogs are usually close to the drain opening — within the first few feet of pipe — which is why they’re often the most DIY-approachable of all drain problems. A hair catcher at the drain opening is the most effective prevention. A drain snake or zip-it tool can usually clear the blockage once it forms.

If your bathroom drain keeps clogging despite clearing it regularly, the problem may be further down the line — particularly in older homes where cast iron drain pipes have corroded or developed rough interior surfaces that catch debris more readily than smooth modern pipe.

Basement Floor Drains: The One That Deserves the Most Attention

Of all the drains in a St. Louis home, the basement floor drain is the one we most often find neglected — and the one where a recurring problem is most likely to signal something serious.

Basement floor drains are designed to handle overflow from water heaters, washing machines, utility sinks, or water intrusion events. In older St. Louis homes — particularly those built before 1970 — they connect directly to the sanitary sewer system through a trap that’s designed to hold water and prevent sewer gases from entering the home.

When a basement floor drain backs up or drains slowly, there are several possible causes:

A dry trap. If a basement floor drain isn’t used regularly, the water in the trap evaporates. A dry trap doesn’t cause slow drainage, but it does allow sewer gas — including hydrogen sulfide — to enter the home. If you notice a sewage smell in your basement near the floor drain, a dry trap is the most likely cause and the easiest fix: pour a gallon of water down the drain to reseal it.

Sediment and debris accumulation. Floor drains in basements collect whatever ends up on the floor — dirt, laundry lint, pet hair, debris tracked in from outside. Over time that accumulates in the trap or drain line and slows drainage. This is a maintenance issue, not a structural one.

Root intrusion. This is where basement floor drain problems get serious. In older St. Louis neighborhoods — Webster Groves, Kirkwood, Maplewood, Brentwood, and much of South City — mature trees with extensive root systems frequently find their way into aging clay or cast iron sewer laterals. Tree roots seek moisture, and a sewer line is an abundant source. Once roots enter the line through a crack or joint, they grow rapidly and can cause partial or complete blockage.

Root intrusion doesn’t announce itself dramatically. It usually shows up first as slow drainage in lower-level drains — the basement floor drain is often the first to show symptoms because it sits at the lowest point in the drain system. A drain that backs up during or after heavy rain is a particularly strong indicator: the municipal sewer is surcharging, and a partially blocked lateral can’t keep up.

A failing or collapsed sewer lateral. Clay tile sewer laterals — common in St. Louis homes built before the 1960s — have a finite lifespan. They crack, shift, and collapse over decades. A collapsed section creates a low point where solids settle and accumulate, eventually causing recurring blockages that no amount of snaking will permanently resolve.

The Drain That Backs Up in Multiple Places

If more than one drain in your home is slow or backing up at the same time — particularly if lower-level drains are affected — the problem is almost certainly in the main sewer line, not in an individual drain.

This is the pattern that most clearly warrants a professional assessment. A main line blockage or failing sewer lateral isn’t a DIY fix, and continuing to use water in the home while the main line is compromised can push sewage back up through floor drains or lower fixtures.

In our experience, homeowners who catch main line problems early — before a complete backup — have significantly better outcomes. A camera inspection of the sewer lateral is the definitive diagnostic tool. It shows exactly what’s in the line, where the problem is, and what the pipe condition looks like — information that determines whether snaking will resolve the issue or whether something more substantial is needed.

What Drain Cleaner Does — and Doesn’t Do

Chemical drain cleaners are worth addressing directly because they’re the most common first response to a slow drain — and they’re frequently misused.

Liquid drain cleaners work by dissolving organic material in the immediate vicinity of the blockage. For a partial hair clog near the drain opening, they can be effective. For a grease buildup deep in a drain line, or for any kind of root intrusion or structural issue, they don’t reach the problem and can create a false sense that the issue has been resolved.

Used repeatedly, chemical drain cleaners can also degrade older pipe materials — particularly older cast iron and certain plastic fittings — and are corrosive enough to be hazardous if they splash back.

Our general guidance: for a first-time, single-drain slow drain, a drain cleaner is a reasonable first step. For anything recurring, anything affecting multiple drains, or anything involving a basement floor drain that backs up, call a plumber before reaching for the chemicals.

When a Drain Keeps Clogging: Time to Call a Plumber

Call sooner rather than later if:

• The same drain has clogged more than twice in a short period
• Your basement floor drain backs up during or after heavy rain
• More than one drain in the home is slow at the same time
• You notice a sewage smell in your basement
• Drains gurgle when other fixtures are used nearby
• Your home is more than 40 years old and has never had a sewer camera inspection

That last point is worth sitting with. In our experience, many St. Louis homeowners with older homes have never had their sewer lateral inspected — and are operating with no visibility into the condition of the most expensive underground plumbing component on their property. A camera inspection isn’t an emergency response. It’s a reasonable maintenance step for any home past a certain age, and the information it provides is genuinely useful.

What Linek Plumbing Company Looks For

When we respond to a recurring drain complaint, we’re not just clearing the blockage and leaving. We’re looking at the whole picture: which drain, what the pattern looks like, how old the home is, whether multiple drains are affected, and whether the symptoms suggest a localized issue or something in the main line.

For basement floor drain problems specifically, a camera inspection is often the most useful next step — not because we assume the worst, but because it gives us real information instead of educated guesses. That’s how we make sure the fix we recommend actually solves the problem.

A recurring clog isn’t just inconvenient. It’s a signal. It’s worth paying attention to.

Frequently Asked Questions