Why My Tub Drains Slowly? – Reasons

Regardless of whether you use a conventional standard bathtub, an octagonal bathtub, or a free-standing bathtub, they all have one thing in common. The water from the tub must go through a relatively narrow drain after use.

Reasons why your bathtub drains slowly

You may have had an experience where after bathing, you relax and let the bathwater run off only to find that nothing has happened and you are still up to your calves in the water.

In this article, we’ll look into what causes the tub to drain slowly.

What Are The Causes Of A Slow-Draining Bathtub?

Bathroom drains are particularly prone to clogging. Our sanitary facilities are in constant use and come in contact with various substances. If a bathtub is not cleaned promptly or used inappropriately, it will lead to clogging.

There are several causes of the slow-draining tub. It may be clogged with or without a gurgling sound and may or may not be associated with a smell.

The extent of the problem is vital as the obstruction can be local or general. In the first case, the clogged bathtub is observed only in a single apartment. In contrast, general blockages arise in the central sewage system of the house and usually need the help of a professional.

The following are some of the reasons for a slowly draining tub.


One of the major causes of a clogged bathtub is hair stuck in the drain.

Long hair looks beautiful, but it has one major disadvantage: it clogs the drains. But even short hairs may accumulate in the drain valve. Over time, more hairs get stuck and clog the pipe. This can easily lead to bacteria decomposition and the development of a bad smell.

In the same manner as human hair, the hair of pets can also lead to a clogged bathtub. It is not uncommon for a dog to be washed in the bathtub and lose a large amount of hair.


Soap residue as well as incorrectly dosed cleaning agents may seem harmless but can contribute to the clogging of the drainage pipe over time.

These residues known as soap scum accumulate within pipes, thereby reducing their diameter. They can also serve as a base for other substances that accumulate within the pipes.

Dirt And Sand

The bathroom is the place where we wash ourselves of any dirt or sand. This can accumulate over time and block the drain pipe.

Even a small amount of dirt and sand can accumulate, especially when combined with other substances in the pipe e.g, soap residues.

Fat And Oils

Due to the bathtub’s size compared to the washbasin, some find it convenient to pour and dispose of various substances and wash them down the drain.

Some of the substances contain fats and oil. Fats, when warm, are liquid; when they cool down and harden, they solidify.

They reduce the pipe diameter more and more until the pipe is totally clogged. Oil can emulsify with warm water so that a viscous mass is created that becomes more and more viscous over time and can also stick in pipes.

Structural Defects

Less commonly, structural defects, such as insufficient slope for the drain, are also responsible for a pipe blockage. If there is a sharp bend in the waterway, hair and soap will build up in this area.

Why my bathtub drains slowly?

This is guaranteed to lead to a clogged tub.

Hard Water

Hard water contains a high amount of minerals. Depending on your location, if the water is hard, it can cause minerals to accumulate and create limescale on evaporation. This can impair the drainage of water through the pipes and also lead to damage.

Damaged Or Clogged Plumbing Air Vent

A plumbing air vent is an empty vertical pipe that connects the drainage system of the house to the exterior and is usually seen on the roof.

This air vent helps to regulate the air pressure within the drainage system. It removes odor and gases while allowing fresh air to enter the plumbing system which facilitates the flow of the drainage system.

When blocked or damaged, a negative pressure is developed, which interferes with the water flow.

Toys And Small Objects

In households with small children, in particular, quite a bit ends up in the bathtub drain. Toys and other small parts often disappear when bathing and go unnoticed.

Problem With The Sewer System

It should be noted that there can also be a deeper issue with the sewer pipes and sewers. Backwater from the sewer or any obstruction in sewage drainage can also manifest as a slowly draining bathtub.

Technical Reasons

The drain of the tub can also slow down for technical reasons, such as incorrect installation or the wrong choice of pipes.

Your bathtub may drain properly but produce a gurgling sound. If a drain just gurgles without smell, this can be an alarm signal, even if the water is draining well. That’s because the gurgling can come from a bottleneck in the form of incipient obstruction that gradually clogs it up.