Why Does Your Drain Slowly Drain? Unraveling the Common Culprits

A slow-draining sink is typically caused by the accumulation of materials such as food, hair, and soap scum. You can usually solve these problems with a drain snake or chemical drain cleaner to break up the clog, but other causes of slow drains may require professional help. This guide covers the most common causes of slow drains, along with possible solutions.

Minor Clogs

While a slow-draining sink is usually caused by a clog, there’s no way to tell for sure without a plumber. This procedure generally consists of pushing a snake or auger with a camera on the end to view the clog.

A plumber can then break up the clog and clear the drain with a strong blast of water.

P-trap Problems

A P-trap is a double-curved section of pipe, so-named for its general resemblance to the letter “P.” Its purpose is to prevent sewer gas from passing back into the building, but it also allows clogs to lodge in the bend.

This problem is particularly likely when you pour grease down the drain because it can settle in the P-trap and allow other materials to stick to the pipe. When this happens, you’ll probably need a plumber to clear the clog.

Vent Pipes

Vent pipes allow fresh air into a drainage system, which helps remove odor-causing gases. In some cases, they can become blocked, resulting in uneven air pressure that causes a sink to drain more slowly than it should.

The most common causes of these blockages include snow during the winter and leaves in the fall. Removal of these materials is usually easy once you know where the outlet for the vent pipes is.

Septic Tank Sludge

An accumulation of sludge in your septic tank can block your main sewer line, slowing the drain of water from your sink. You’ll need a plumber to diagnose and fix this problem since homeowners usually can’t access their septic tanks.

A solution of bleach and water can often dissolve the sludge, but a severe blockage may a plumber to physically remove it.


Drainpipes are connected to the main sewer line for the specific purpose of draining water from it. Any problem with the drainpipes can cause slow-draining sinks, including clogs, leaks, and sediment buildup. You’ll need a plumber to diagnose and fix any problems with drainpipes.

Old Plumbing

Plumbing generally has more frequent problems when it gets old, including slow drains. Drains, fixtures, and pipes can all develop problems over time that interfere with the flow of water through a plumbing system.

Minimize these problems by keeping your plumbing in good condition with regular maintenance, including an annual inspection by your plumber.

Tree Roots

Tree roots can cause all sorts of problems if they’re able to grow into the sewer line, including leaks and slow drains. A plumber must fix this problem by removing the tree roots and replacing the damaged drain.

This repair is more expensive and time-consuming than other procedures for improving a slow drain. In addition, the only meaningful preventative action is to remove all nearby trees, including their roots.

Solid Objects

Drains are usually clogged by thick liquids and semisolid materials, but small solid objects like jewelry and toys can also cause water to drain slowly. You can often solve this problem by simply straightening a clothes hanger and using the hooked end to pull the item out of the drain.

If this procedure is unsuccessful, you’ll need to call a plumber to remove the affected section of the pipe and retrieve the object.

Many types of plumbing problems require professional help. Our team at Pilot Plumbing has years of experience in diagnosing, repairing, and upgrading all types of plumbing systems. Schedule an appointment today if you have a slow drain. You can also reach us at (936) 788-6829.

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