What Causes Sewer Blockages?
If your home’s plumbing has slowed down to a crawl, the issue is probably deeper than a simple drain clog. Sewer blockages can develop gradually over time, eventually causing wastewater …

Probably not panicking is the right call, but it’s good that you’re looking at it! A slow or standing bathtub drain is one of those problems that ranges from “five-minute fix” to “you need a plumber today,” and the difference matters.
The Centennial and Denver plumbers at Bell Plumbing, Heating, Cooling & Electrical have been helping homeowners sort out exactly these kinds of situations since 1926, with same-day service when you need it handled fast.
Here’s a practical breakdown of what’s likely going on and what to do about it.
Most slow drains come down to the same handful of culprits.
The most common by a wide margin. It sheds every time you shower, catches on the drain stopper or pipe walls, and tangles with everything else going down the drain. Over time that tangle becomes a serious blockage.
Sneaker culprit. Bar soap contains fats and oils that don’t fully dissolve in water. They leave a sticky residue that coats the inside of your pipes and gives hair and debris something to grab onto.
Particularly relevant in Denver. Colorado’s water tends to run hard, meaning it carries elevated levels of calcium and magnesium. Those minerals slowly deposit on pipe walls and narrow the passage water has to flow through. If your drain has been getting gradually slower over months or years, this is likely a factor.
Most overlooked. Sometimes the stopper mechanism, especially on older tubs with a lever-style drain, gets gunked up or slightly misaligned and sits partially closed without you realizing it.
Less common but worth knowing about. Your plumbing system has vent pipes that run up through the roof to regulate air pressure in the drain lines. If one gets blocked by debris or nesting animals, it can create a vacuum effect that slows drainage throughout the house, not just the tub.
If it’s just your bathtub and the problem came on gradually, there’s a reasonable chance a DIY fix will take care of it.
Start by pulling the stopper out completely and cleaning it. Hair and soap buildup often collect right at the stopper base where you can reach them by hand. A drain snake or zip-it tool can pull out deeper hair clogs without chemicals or much effort. For mild buildup, pour half a cup of baking soda down the drain followed by a cup of white vinegar, let it fizz for 20 to 30 minutes, then flush with hot water.
One thing worth avoiding: chemical drain cleaners. They’re hard on pipes, especially older ones, can damage seals, and often don’t fully clear the clog anyway. They tend to push the problem a little further down the line rather than solve it.
Some situations are clearly beyond the reach of a plunger and some hot water. Call a professional Denver or Centennial plumber if:
A plumber won’t just snake the drain and call it done. For persistent or serious clogs, professional drain cleaning often involves hydro jetting, a process that uses high-pressure water to completely scour the interior of the pipe, clearing out mineral scale, soap buildup, grease, and root intrusion that a cable snake can only partially address. It’s a more thorough solution, and for drains that have been slow for a long time, it makes a real difference.
If a main line issue is suspected, a camera inspection lets the plumber see exactly what’s happening inside the pipe before recommending any repairs. That diagnostic step prevents unnecessary work and makes sure the fix actually addresses the problem.
Once your drain is clear, keeping it that way is mostly about consistency:
A slow bathtub drain is usually not an emergency, but it is a signal worth paying attention to. Catch it early and you’re probably looking at a quick fix. Ignore it long enough and you can end up with a full blockage, water damage, or a much more involved repair.
If you’ve already tried the DIY route and the drain is still sluggish, or if anything about your situation matches the warning signs above,
Bell’s plumbing service team is available same-day and knows Denver homes inside and out. Book an appointment here and get it sorted!
Some fixes are simple. Others need a pro’s touch. If you’re unsure, let Bell take a look—we even offer free second opinions. Call us today!