We often receive calls about a bad sewer smell or strange gurgling noises from our customers. The bad smell is usually caused by one of a handful of things that most people can tend to without any special skills, you just need to know what to look for. This short article will present the most common causes of sewer odors and just might help you avoid calling out a plumber.

Do you ever use it?

Big tubs like this in the master bathroom with a separate shower sometimes go unused for months at a time.

Big tubs like this in the master bathroom with a separate shower sometimes go unused for months at a time.

If you have a large garden tub, a basement shower, or guest bathroom that can go months without any use, try running some water down the drains first. There should always be water in the p-trap of a drain. Every drain in your home should have a p-trap installed somewhere near the drain opening. Seldom used fixtures will sometimes go without use long enough for the water that should be in the trap to evaporate. P-TrapWhen the p-trap is dry there is nothing to keep sewer gasses trapped inside the pipe. If you are hearing an echo type noise when you flush the toilet, it usually is coming from a dry p-trap nearby. The solution is as simple as running water for 10-30 seconds. This will fill up the p-trap and the gases will get sealed back in the pipes.

Kitchen Islands

An island doesn't leave anywhere to hide a normal drain vent.

An island doesn’t leave anywhere to hide a normal drain vent.

When a kitchen sink is in an island with no wall to hide a vent line in, plumbers use a special vent to allow the drain to flow smoothly. These vents are called air admittance valves and most plumbers refer to them as Studor vents. They are negative-pressure-activated, one-way mechanical valves, used in a plumbing or drainage venting systems to eliminate the need for conventional pipe venting and roof penetrations. Simply put, they are a special fitting with a spring loaded rubber disc inside that allows air into the pipe, but is supposed to keep water and gases trapped inside. They work great at allowing water to flow through your drain system. The only problem is that they don’t last forever. When the spring fails, or the rubber disc gets damaged or loses its shape they no longer keep those stinky smells at bay. They are most often found under kitchen sinks, but can also be installed on any drain in the house. The good news is that they usually are threaded on and can be removed and replaced using basic DIY skills.


The wax seal is crucial because the toilet IS the p-trap!

The wax seal is crucial because the toilet IS the p-trap!

Unlike all the other drains of your house which connect to a p-trap, the toilet actually houses a p-trap inside of itself. Toilets sit on the floor over a large open pipe. The only thing that keeps the pipe connected to the bottom of the toilet is beeswax and a couple bolts. If your toilet is able to rock or slide around the wax seal underneath it may break, allowing sewer odors to escape. If smells are coming from your bathroom and you already ran water down all the drains, grab hold of the toilet bowl and see if you can rock it side to side, front to back, or if it can rotate around at all. If you have any movement, there is a good chance the wax seal has been broken. The toilet will need to be pulled up and reset. This will cause serious water damage over time, so even if you don’t have any odors, get the toilet pulled up and reset it using a new wax seal.

Garbage Disposals

Sometimes we get called out and find that the odor isn’t a sewer smell at all. Some plumbers become highly attuned to malodorous scents. Others lose their sense of smell altogether. If you get the former they may point you to the garbage disposal. The rubber splash guard is usually pretty nasty, but they can be easily cleaned. In higher end disposals the splash guard is actually designed to be removed and can be cleaned in the dishwasher, but most homes will have the non-removable style. A great way to clean it is to take an old tooth brush and just scrub the top and bottom of the rubber. You will be shocked at how much crud builds up on these things. Once you finish cleaning the rubber make yourself a nice cocktail, just keep the citrus peels handy. You don’t need a fancy garbage disposal cleaner, just ice and some citrus peelings.

  1. Turn on the cold water and leave it running.

    Clean off this gunk

    Clean off this gunk

  2. Throw a bunch of ice down the disposal, 3-4 trays if you have it. Better yet, just go ahead and empty all that old ice sitting in your ice-maker bin if you can slide it out easily. Fresh ice tastes better anyway. The ice actually knocks around all the stuff clinging to the inside of the disposal, but it can’t jam it up. If it does, just wait until it melts and you’re good to go.
  3. As you have the ice getting crushed up, throw in small pieces of lemon or lime peels. Keep them somewhat small so they don’t give the disposal too hard a time. Those small wedges you used for your cocktail should be just about the right size. The citrus is a natural degreaser, and it has a pleasant smell to most people. It is a cheap way to both clean and deodorize the disposal.
  4. Once it is clear just let the water run for a good solid minute.

If any odors persist check out our Bio-Clean drain treatment. It will literally eat any of the nasty gunk that the ice and citrus can’t clean away. It is also great for clearing away the gunk slowing your drains down and is great for septic systems too. Just make sure you never use traditional drain cleaners like Drano. Most drain cleaners are sand and bleach, or acids that will actually destroy the metal parts of a garbage disposal and older drain systems. Worst of all they kill off the good bacteria your drains need, creating a dependance on the harmful products you shouldn’t be using anyway.