Why Drains Smell & How To Stop It

Woman in bathroom washing her face over the sink
Woman in bathroom washing her face over the sink

Have you noticed a strong, unpleasant smell coming from your sink or shower drain? This smelly drain odor can be described as a rotten egg smell in your house, and it’s not only unpleasant but can also be a sign of a more serious and unhealthy problem with your plumbing! Fortunately, the are simple and effective solutions to this stinky situation!

Here’s what you need to know about the most common causes of drain odor and how to prevent them.

Biofilm: Hair, Soap Scum and Smelly Drains

One of the most sources of smelly drain odor is the buildup of organic matter in the drain. Known as biofilm, it can include things like hair, soap scum, food particles, and other debris that gets caught in the drain and begins to decompose. As this organic matter breaks down, it can form a film and release gases that can create a foul odor. This is particularly the case in shower drains, where hair and soap scum can accumulate over time, decomposes and release an awful odor.

How to get rid of bathroom drain odor

Dry P-Trap: Sewage Smell

Another possible cause of drain odor is a dry P-trap. The P-trap is a curved section of pipe that is found under sinks and other drains. It is designed to hold water, which creates a barrier that prevents sewer gases from backing up and entering your home. If the P-trap dries out, either because the drain hasn’t been used in a while or because it’s not holding water properly, sewer gases can escape into your home, delivering a non-stop source of sewage smell stink!

Poorly Maintained Septic System

A third potential cause of drain odor is a problem with your septic system. If you have a septic system, it’s important to have it inspected and maintained regularly to ensure that it’s working properly. If there is a problem with your septic system, it can cause sewer gases to escape into your home, which can create a strong odor.

Dirty septic tanks can cause smelly drains in the house.
Worker cleaning a backyard septic tank

With septic systems, it’s also important to understand that septic tanks contain naturally occurring “good bacteria,” that dissolve and consume solid waste. Septic tanks need this type of bacteria to function properly.  However, the use of some household cleaning products (like bleach, for example) can kill the good bacteria preventing decomposition of the waste. And when that happens? Drains stink!

How to Prevent Smelly Drain Odor

Removing the kitchen sink trap for cleaning
Removing a dirty p-trap under a kitchen sink for cleaning.

So, now that we know some of the common causes of drain odor, how can we prevent it? Here are some tips:

  1. Keep drains clean: The best way to prevent the buildup of organic matter in your drains is to keep them clean. You can do this by regularly flushing your drains with hot water, using a bottle brush, or using a plunger to clear clogs. Drain cleaners can work too, but they are very caustic and must be used with extreme caution.
  2. Use a drain screen: Installing a drain screen can help prevent hair and other debris from going down the drain in the first place, reducing the likelihood of buildup and odor.
  3. Use a garbage disposal properly: If you have a garbage disposal, be sure to use it properly. Only put food waste down the disposal that can be easily broken down, and avoid putting things like coffee grounds or eggshells down the drain. It’s also helpful to keep you garbage disposer clean. There are a wide variety of garbage disposer cleaners available to help. With most, you just toss in a cleaing tablet, run hot water and let cleaners scrub away the stench!
  4. Check your P-trap: If you notice a drain odor, it’s important to check your P-trap to ensure that it’s holding water properly, and allowing unhealthy sewer gas to backup into your house. This is especially important in sinks or showers that are not used frequently, which allows the water in the trap to dry out. If it’s not full, simply run water down the drain to fill the trap.
  5. Have your septic system inspected: If you have a septic system, it’s important to have it inspected regularly by a professional. This will ensure that it’s working properly and prevent problems like sewer gas odor. In most cases, septic systems need to be cleaned and service every couple of years, or more frequently if there a problem.

Simple Solutions Stop Sink and Shower Drain Smells

In conclusion, if your sink or shower drain smells like rotten eggs, it’s important to address the problem as soon as possible. The most common causes of smelly drain odor are the buildup of organic matter, a dry P-trap, or a problem with your septic system. By following the tips above, you can prevent drain odor and keep your home smelling fresh and clean.