Smells in drains is caused by decomposing organic gunk trapped in the drainpipe, dry P-traps, clogged vent stacks, poor plumbing among other factors.
If only one drain is smelly, the problem is isolated to its drainpipe but if all the house drains are smelly then you most likely have a clogged plumbing vent.
Most of the waste that we dump down our drains are almost always organic. And when organic matter stars to decompose it emits a foul smell.
While most of the waste will flow down the drainpipe and out into the city municipal sewer lines, some of it is left trapped in the drainpipe. This is the waste responsible for the smell in your drains.
A sewer smell in drains is most of the time caused by an empty P-trap. This happens when the drain has not been used for a long time, the P-trap is leaking or the plumbing vent is clogged, forcing sewer gases through the drains.
While there are several ways to deal with a smelly drain, it is always recommendable to go with a natural, homemade and eco-friendly solution. This especially makes sense if you are on a septic system and not want to mess up with the septic tank microbes.
To get rid of a smelly drain, pour 1 cup of baking soda down the drain and follow it up with another cup of vinegar. Wait for about 15 minutes then blast hot water through the drain. If the plumbing vent is clogged, climb to the roof of the house and clear it. Fix leaking P-traps or replace S-traps with P-traps.
How to Clean Smelly Drains
Cleaning smelly drains can be a really easy and fast task depending on what is causing the smell. I will therefore start with the easiest method and gradually move to the most time-consuming methods.
This are some of the best ways to clean a smelly drain:
1. Run Some Water Through the Drain
Have you just returned from vacation and all of a sudden there is a sewer smell coming from your drains? Or do you have a sink, toilet, shower or bathtub you rarely use (maybe in your guest bathroom)?
The reason for the sewage smell is most likely because the water in your P-trap has evaporated, and as a result sewer gases are coming up through the drains.
To start with, what is a P-trap? A P-trap, also known as a drain trap is the U-shaped bend under your drains. You can see it in your toilets, under the kitchen/bathroom sinks but the ones in your shower, tub or washer are not visible.
A P-trap as its name suggests traps potential drain clogs, preventing them from clogging the drainpipe farther away. Removing clogs from P-traps is way easier than having to pull out clogs tens of feet away from the fixture.
Another important function of the P-trap is to hold a little amount of water at all times thanks to its shape. This is the water you see at the bottom of the toilet bowl. It prevents sewer gases from coming up through the drains, by creating a barrier.
If the drain has not been used for a while, the water in the P-trap will evaporate. Even if not all the water will evaporate, when enough water to break the seal evaporates you will have a sewer smell coming from your drain.
The solution to this problem is the simplest of them all. You just need to pour water down the drain, to restore the amount that evaporated. If you are coming back home from vacation turn all the faucets to drains for a few seconds and flush the toilets. Don’t forget the washer drain as well.
2. Use Baking Soda, Vinegar and Hot Water
Baking soda and vinegar are a fantastic pair when it comes to cleaning and odor elimination. When you mix baking soda (a base) and vinegar (a mild acid), a fizzing reaction takes place which breaks down gunk in drains and with the help of water hot you will just need to flush them down the drain.
The 2 substances are also very effective in clearing clogged drains. It is very easy for a smelly drain to develop into a slow draining or even fully clogged one.
When you have an unpleasant smell coming from your drain, it means you have organic gunk (usually trapped in the P-trap) that is decomposing. If you do not deal with it, more gunk will be trapped there resulting into a clog.
Organic gunk in drains is also the main source of nourishment for drain flies. If you want to prevent a drain fly infestation in your home, clean your drains with baking soda, vinegar and boiling water frequently.
Here is how to get rid of smell in drains using baking soda and vinegar:
- Start by running hot water down the drain. Unlike cold water, hot water is very effective in dissolving and breaking down gunk in drains.
- Pour 1 cup of baking soda down the drain.
- Add another cup of vinegar slowly as it reacts very fast with the baking soda.
- If your drain has an overflow (like sinks and bathtubs), insert a funnel in the overflow and pour little amounts of baking soda and vinegar as well. Unknown to many people, overflow drains can be a major source of smells in your fixtures.
- Wait for about 15 minutes for the solution to work out its magic.
- Blast hot water down the drains to wash down the gunk. Remember to attach a funnel to the overflow drains as well. Do not use boiling water if you have a ceramic fixture, like a bathroom sink as it can crack. Hot water from the faucet will work just fine.
Getting Rid of Smell from Kitchen Sink Drain
A kitchen sink drain is designed a little different so you should pay more attention to it. If you have a garbage disposal, it could be a major source of smell in your kitchen sink drain.
Apart from the baking soda, vinegar and boiling water, you can do more to get rid of smells from your garbage disposal. Here is what you do:
- Fill your garbage disposal with ice cubes
- Add a 1/4 cup of salt
- Turn on the cold water faucet.
- Start your garbage disposal and let the ice and salt scrape the inside of your garbage disposal until the ice completely melts.
- Cut a lemon into several slices and thrown one at a time inside the garbage disposal. This will leave it smelling fresh.
- Do it often.
For more information on how to clean a smelly garbage disposal check out this post.
A dishwasher can be another source of smell in your kitchen sink drain. The problem could be coming from the dishwasher itself or its drain house.
If the dishwasher drain house is not properly installed, it could be a constant source of an awful odor. The drain hose should be installed in such a way that it is not allowing gunk and water to collect inside, which is usually the source of the smell.
To check if the dishwasher is the culprit, disconnect it from the sink drain tailpiece or garbage disposal and smell it. If indeed it is the one responsible for the smell, have it installed properly and start a short cycle in the garbage disposal using baking soda and vinegar.
3. Clean the P-trap
If you are dealing with a smelly kitchen or bathroom sink drain, removing and cleaning the P-trap is often an easy and fast way to deal with the smell.
Here is how to proceed:
- Remove items under your sink. If you use the area under your kitchen or bathroom sink to store items, remove them to give yourself enough room to work.
- Place a small bucket or pan under the P-trap. Since there will be water inside the trap, you do not want it spilling on the floor.
- Loosen the P-trap connections. If you have a plastic drainpipe, the connections will most likely be hand tight. With a metal drainpipe you will however need a wrench or slip-joint pliers. You will notice that the P-trap has a long and short arm. I like to start with the short arm connection so that all the water flows out using gravity.
- With the P-trap out, check if there is gunk inside that could be the source of the smell. Drop it in a bucket of hot soapy water.
- If you have a double kitchen sink, the second bowl is usually connected to the bowl with the P-trap using a piece of pipe called a tee. Disconnect the tee and drop it in the soapy water as well.
- If you have a garbage disposal on the second sink bowl, disconnect its drain hose/pipe and drop it in the soapy water as well.
- The P-trap is usually connected to the sink flange using a vertical pipe called a tailpiece. To clean the tailpiece, insert a toothbrush in the soapy water and use it to clean the tailpiece.
- Clean the P-trap, tee and garbage disposal drain hose/pipe and connect them back.
- To completely get rid of the smell, pour a gallon of hot water down the drain.
With shower/bathtub drains, you can first pull out hair from the P-trap and then clean it with hot water. More on that in this post.
4. Clear the Plumbing Vent
A plumbing vent is the vertical piece of pipe which runs from your main house drainpipe through the roof of your house. Its main function is to expel sewer gases and bring in air to the drainpipe to help in draining.
Plumbing vents can be clogged by dry leaves, tennis balls, bird nests, dead rodents, snow among other things When that happens, sewer gases will not be expelled from the drainpipe and air will not flow in.
This creates a negative air pressure in the drainpipe, whereby sewer gases forces their way out through the P-traps in form of air bubbles. When you see a toilet bubbling after being flushed this is usually the reason.
A blocked vent can also cause the water in the P-traps to be siphoned out into the drainpipe. If for instance you flush the toilet, you will hear the bathtub/shower drain gurgling. This is because a vacuum is created inside the drainpipe which sucks in the water from the trap.
Apart from the sewer smells from the drains, the drains will also be draining slowly, while the toilets will have a weak flush. For proper draining of fixtures, the vent stuck need to be able to bring in air inside the drainpipe.
Here is how to unclog a plumbing vent:
- Use a ladder to climb to the roof of the house, armed with a garden house.
- Check if there are clogs from the top of the vent that you can easily pull out with your hand.
- Stick the garden hose inside the vent and try to use it to dislodge the clog.
- Have someone turn on water to the garden hose. Probing the clog with the help and weight of the water might be enough to unclog the vent.
- If the clog is really nasty, bring on the drain snake. Snake the vent until you pull out the clog.
5. Replace an S-trap with a P-trap
Before P-traps, we used to have S-traps. S-traps are installed in the same position and way like P-traps, only that they look like an S and not an inverted P.
S-traps are no longer used as they are not very effective in sewer gas prevention. This has to do with their design.
S-traps have a long section of a vertical pipe which creates a vacuum then the fixtures drains. The result of this is that water is siphoned out of the trap, breaking the barrier. As a result, sewer gases flow out of the drains unrestricted.
Check under your kitchen or bathroom sink to see if you indeed have a P-trap and not an S-trap. If you have an S-trap you will need to replace it with a P-trap.
And basically that is how to get rid of smells from drains. I hope that this guide was helpful