Sewage gas smell at the sink

There must be a blockage in the pipe. If a toilet is flushed the additional surge of water cannot pass the restriction fast enough and the air is then compressed and forced past the trap below the sink.

A vent pipe at each toilet might help.

The cause of the blockage must be removed. The roots of trees find their way into earthen ware pipes.

A hardware shop sell potent stuff (Mixture) that will even dissolve blockages by human hair.

A drain specialist might be advisable.

Our drain-surgeon is called Moses - His motto - Moses will lead you out of the

Thanks for your help. The builder must have screwed up since the house is only 6 months old.

In the kitchen sink the number one source for bad odors is the "Disposal" (well in the U.S. at least). This handy little appliance is often neglected because it can be difficult to clean depending on what garbage has been placed in it. A common mistake made is to discard celery in the disposal, this is VERY bad because the fibers wrap around the parts inside the disposal and are near impossible to remove without disassembly or waiting for them to rot out. Other foods that are fibrous or greasy can also build up in the common disposal then rot resulting in foul odors.

Ok I am assuming that you have a disposal so if don't just ignore what I say otherwise I would recommend regular cleaning of the disposal and avoid using it in place of the garbage can for food scraps when possible.

To clean a disposal try filling the sink with hot soapy water periodically, once filled start the disposal and pull the drain plug on the sink. The hot soapy water should remove most debris and foul odors if done regularly otherwise several cleanings may be needed.

Good luck, lord knows how bad odors can ruin a nice house.

Hi slong,

Two things you can do. Put the peel of a couple of oranges/lemons through your disposal with plenty of water. If the smell persists it is very possible that the smell is in fact coming from your waterheater! Many water heaters have a sacrificial cathode in them and when these go wrong produce a smell akin to sewer gas. Have a plumber replace the cathode and your problem will be past. Try the citrus fix first. Works realy well.

Cheers

Thanks for your help JCMCF57. This is a possibility since the faucet is always on a neutral (hot/cold water: 50/50) position. I'll turn the hot water off and see whether the smell disappears.

Sorry to split hairs, but I think you mean sacrificial annode

A Few other other possibilities

1. There should be a water trap under each drain. (this is a "U" shaped piping under the sink) It traps water so no gasses return up the drain. If this is not there the plumming was done wrong.

2. If a shower or tub that has not been used for a long time, this trap may have dried up. Simply run the water in all your showers, tubs, etc for a minute and the smell will go away.

3. As in the previous answer, A vent is required to go to all your plumming accessories. This vent should go through the roof and not be blocked. (Looks like a 3 or 4" pipe" Make sure there is no blockage such as bird nests etc. It is also possible the plumming installer was cutting corners and did not hook up all the plumming to a vent. If this is so, your house should still have a warranty and the plumming may have to be redone.

there are time when atmosphric pressure is greater than that inside of the vent line,on these occasions a ordor will sometimes vent inside the house a good cure would e to install a one way struder valve in the line venting to the outside,I have installed this type of valve with good success,ordors are always the most difficult to find the source because everyone has a different sense of smell,good luck

Care must be taken when making modifications like this. The "Vent" line is more accurately described as a "Vaccum Break line" and its modification can result in your water traps being syphoned to the point that sewage gases can enter the living space.

Sometimes these are also called "Durgo" valves [for information] in the UK.

There could be gunk, hair, etc caught in the drain plug.

Under the sink there is a lever sticking out the back of the drain. Put a bucket underneath. Unscrew the round nut , hang onto the drain plug, and and pull the lever out. With the lever out, you should be able to pull the plug out to clean it.

Clean the drain, a bit of bleach should kill anything growing (do not mix with any other chamicals)

reassemble

Although all of these posts offer some great advice. You more than likely have a high concentrate of Hydrogen Sulfide gas (especially if you have well water) or disolved sulfides in your water (if you have city water).

These gasses / materials rise to the highest point in the supply side of the plumbing (right to the valves of faucets / showers, etc) and concentrate there. You'll only notice them for a moment when released, and even then, not at every sink or water supply in the house. The run of water line, pipe size and style all have bearing on the amount of these materials that are gathered at any given place.

Your best bet is to take a water sample to have it tested (your local Chamber of Commerce should be able tell you where to look, and probably advise an agency that will do it for free).

There are filters that can take care of the problem if you find it unbearable. A plumbing mistake is highly unlikely that would cause a gassy odor, especially in a newer home. Your plumbers are used to meeting codes (and would have had to have all of their venting work inspected), and usually don't need to cut corners.

If its in the water it should linger the so fill a glass and check.

These are all good answers but the most probable cause is a lack of a trap under the sink and/or the lack of a vent line.

Remember everyone...he said this happens when he opens the faucet...If there were a missing trap or plugged vent, it would stink all of the time.

Very likely you have a blockage in your system somewhere. Try using drain cleansers or unclogging your trap.

If the oder is coming out of your faucet, I think that your problem is a lot more serious than what's been stated here. It sounds as though there is real cross-contamination into your drinking water. I'd stock up on bottled water for awhile, and don't wash the dishes. Next, I would get on the phone to the water company and demand that they send someone out to check the situation immediately.

But hey, it's your house and your body...

To make sure it isn't coming from the drain, run the water into a pan or bucket. My guess is that it is the hot water. Water dissolves gasses more readily when it is cold. When it is heated by the water heater they come out of solution. Like someone else said, try hot and cold and see if there is a difference.

Assuming that you have the correct plumbing under the sink in question (u-bend to maintain a water/air lock), you need to find and identify the causes and exactly when it happens.

If you notice it for example it happens after an upstairs toilet is flushed (blame the wife!!), maybe more than once, but without adding any extra water in the sink (each flush may remove a certain percentage for example) then the rush of water from above may cause the water in the u-bend to be sucked out......you need to add a pipe from the waste water, up above roof level to allow pressure differences to happen no more and high enough that you can't smell the gas!!

When the problem happens, undo the u-bend and see if there is still enough water in it to seal.......after checking first how much water there is in normal use BEFORE the problem happens!!!

Start simply, make notes and keep the infos together, we will help you.....

Is the kitchen sink the only location the odor is noticed? If it is the hot water then the smell will also be present in the shower/bath. If not then it is one of the problems others have listed. I have noticed a similar problem with my disposal before. someone suggested the peels of citrus. Don't bother with the peel just put the whole fruit down there and grind it up without running the water and let it sit. Also, you can use ice cubes and baking soda. Same thing, don't run the water and let it sit. The ice cubes will help dislodge any trapped/stuck food also.

Check with your neighbors to see if they are having a similar problem or even if this is a "normal" situation.

After checking all the above then call the Water Department and report it. They will more than likely ask you to bring a sample to them for analysis.

I forgot to mention, if it really is sewage gas, then do not have nacked lights or cigarettes near, it can be flammable!!

One possibility

Check the vent pipe to see if it has not become home to insects or other wise plugged. If you are on your own septic system the septic tank should also be vented.

The smell could be due to rotting food particlwes inside the pipe. SOmetimes certain bacteria known as SRBs accumulate in the pipe and they digest the organic matter in the pipe releasing H2S gas. The quickets way to clear is to pour a bottle of soda also known as sparkling water, followed by a solution of sodium hypochlorite. The combination will release the accumulated blocks and removes the odours and odour causing bacteria.

I once rented a holiday house with some "sounds" coming from the sink. On complaining the management send someone to fix it and he only poked a rod into the pipe from the outside and declared it ok. but i saw that the problem was a fat / soap / pieces of food that was clogging the pipe. As the smell was still there i went to the shop and bought a bottle of muti (caustic soda and whatever mixture) and used it. the rest of the stay was odorless. Note caustic soda will stain the stainless steel parts big time.

My advice is

to clean the system.

Make sure vents and traps are installed and working.

Builders sometimes plug the open end of pipes temporary and then forget to remove the plug when they continue.

The drainage system must be checked to make sure that, when a toilet flushes, it doesn't suck the water out of the U-bend under the sink; the purpose of the water left in the U-bend is to make sure that sewage smells don't enter the house.

Installing an air-admittance valve, or extending the toilet drainage pipe outside the building to a high level (builders sometimes call this a "stench pipe") may solve the problem.

Deepening the U-bend under the sink may also solve the problem.

With building contracts there is usually a warranty period upon completion. Check what the builder can do to help under warranty in the contract.

hello,

this is hari kishan and i am final year civil engg. student... i think sink is not provided with a trap which is kept at the bottom of the drain pipe of the sink .this trap holds some water that is going out and prevents the foul smell (sewage gas) to re-enter the pipe from the drain ...so ask ur plumbler wheather it has been provided or not . if not , ask him to keep it. if provided ask him to check wheather it is working(with out any leakages) or not.... !!!!!!!!!!

BYE....

Guys, we all know about the drain, and baking soda, and bleach, and all that stuff. But (and this is a big but), if the smell is coming from the faucet (as slong first said), and not the drain, he/she may have a far more nasty problem.

So, slong, is it coming from the drain or your water tap?

Vermin - I think you are right one should look at the faucet. You don't seem to get a reply to your question.

I will attempt to Analise his first sentence the way it is done in law.

"When I open the faucet I smell sewage gas coming out from the sink for a couple of seconds."

1 When I open the faucet - this implies that before the faucet is opened no smell can be noticed.

1.1 The empty trap or blocked drain etc can be ruled out.

1.2 It does not rule out that something may be rotting in the trap and the odor is trapped underneath the surface of the water.

1.3 but rotting will continue and odor will eventually be released. As nothing is mentioned about other occasions of odor - can it be ignored?

2 When I open the faucet I smell (sewage gas coming out from the sink)

2.1 The moment the faucet is opened the smell is detected.

2.2 I don't think slong is qualified to name the origin and direction of the smell

2.3 The source of the odor may therefore be the faucet.

3 for a couple of seconds.

3.1 the amount of odor is small

Possibilities:

V. Something is rotting in the faucet and being lighter than air will stay at the highest point until displaced when the faucet is opened. The odor may also be trapped underneath the valve and released when opened.

S. Sulfur or something similar might be present in the water and released or react with iron the pipe and release a smell.

O. something rotting in the trap and released when disturbed.

Judgment:

More evidence is needed before judgment can be passed.

A. A bowl or container must be placed underneath the faucet before opening.

B. Water should be poured into the sink.

Thank you for your comments and help.

My apology for not including the following information:

- The sink I was referring to is in the master bathroom not in the kitchen.

- There are two sinks in the master bathroom about two feet away from each other. Only one sink produces the sewage gas odor which I find it strange. If it was pressure build-up in the sewage line then both sinks should have the same problem. If it was the hot water then both sinks should also show the same problem. I'm puzzled.

Meanwhile I did the following tests:

1. I close off the hot water supply and the sewage odor disappeared when I open the faucet which means it doesn't come from the hot water/boiler.

2. I added clorox to the sink, the odor disappeared but came back after a couple of days.

The problem must be caused by pressure build up in the sewer line but why only on one sink. Unless the two sinks although close to each other, are not connected to the same sewage line which I think is not very likely.

Could you post a picture of the pluming under the sinks in question?

Lets say the plumbing it done right and there is no problems with your water. that would leave the possibility that there is Defect in your sink. Moust bathroom sinke have an overflow hole towards the top of the basin that is connected to the drain, If there is a defect (bur, bump, extra porcelain) that is trapping a small amount of water and this water stagnates. Try this.... Overflow your sink once a day for 2 minutes for a week or two. If the smell goes away and stays away but comes back when you stop the water flush you will know that it is the sink overflow.

Even if the sinks are closely connected in all respects, one u-bend will clear first, always the same one.....thats normal. Probably when a toilet flushes..

Look at my previous post, do what it says.

Let me just confirm test 1

1. I close off the hot water supply and the sewage odor disappeared when I open the faucet which means it doesn't come from the hot water/boiler.

the data implies that it do come from the hot water.

Can you perform the tests for us to isolate the source of the odor?

1 Put a bowl or container in the sink and open the faucet. (no water must be allowed to go to the drain.)

2 Pour hot water into the sink (similar flow as from faucet)

When was the odor detected?

A photo of the faucets, pipes and sinks would help.

Just another question. Are the sinks metal or porcelain basins?

Porcelain basins are often formed with cavities inside to allow for shrinkage when drying. The cavities are mostly interlinked with the overflow. Something trapped inside might be the cause of the odor.

Could you perform ther following test?

Close the plug and fill the basin (sink) to above the overflow. what is the result?

Hendrik, I'm really impressed with and enjoyed your commentary. Your legal explanation was a riot. Sure is a lot of speculators all blaming the trap.

I've had 2 different cases of foul odors coming from faucets, specifically when the HOT water was used and no amount of flushing cured either of them. They were contaminated with iron bacteria that gets into the pores of the tank liner and can NOT be neutralized or killed by chlorox or ammonia or anything. Both times it was replacing the HWH !

Iron bacteria can be seen as evidence of orange slime or snot in the stubs of the water heater.

I don't know about you but my smeller can easily discern between hydrogen sulfide smell ( common in many wells ) that smells like rotten eggs versus SEWAGE which no matter whose septic you open, sewage always smells the same....

Interesting! These are chemosynthesis bacteria? Are they that indestructible?!

How does one become infected in the first place?

I do have some legal background and became involved with the technical aspects in legislation but my involvement grew to more.

It was suspected that you are withholding information and calling you unqualified did the trick.

I am glad you enjoyed the comments - I aim to please, you aim too please - Urinal.

Cant something be done to remove or dilute the cause earlier in the system?

You didn't call me unqualified, I jumped in here for the first time by responding to you about enjoying your response to the original.

I'm not a chemist or biologist, I'm an HVAC designer. But In both instances, I poured several gallons of pure chlorox into the water heaters and filled them up slowly. Both times, the water heaters of course stunk like chlorine but when that washed out, slowly but surely the smell returned and within 2 months was as bad as ever.

I never heard of this on "city water" that is usually heavily chlorinated, rather always in private wells.

It was just another possibility for the person's odor which is annoying if its hydrogen sulfide but DEADLY if its indeed sewage which is unlikely.

Sorry I ass-u-me-d you to be slong.

Thank you for your advices/tips.

The problem is finally solved. A plumber dismantled the drain of the sink. He found a brownish (looks like glue) deposit at the connection of the drain pipe and the sink. The sewage smell came from this brownish stuff. He flushed off this brownish stuff and replace the drain pipe. It has been approx. two weeks since then and the sewage smell is gone.

If the actual fitting that had that foul material in it could be cheaply replaced, you'd be wise to do it. If that stuff was that powerful, it might grow back and bad bacterias in an area where they get on your hands and ultimately in "the food chain" .....yuk!

I've seen a lot of "skank" in drains but never had any that produced sewer smell.

Thank God the Pong has gone at last!!!!!

Late addition - great thread

My similar sink problem was the overflow. The porcelain sink had an integral overflow that connected to the drain slightly below the bottom of the sink. There is a side opening in the stainless steel drain insert in the sink that aligns with the overflow opening in the sink. The problem is that the lip of of the stainless steel opening is slightly higher than the discharge from the porcelain overflow. The lip created a 'dam' that allowed collection of foul smelling gunk. My temporary solution was to pour some bleach down the overflow. Long term solution is to replace the stainless steel insert and ensure the opening aligns with the porcelain outflow. A diagram would be much simpler to explain!

Gentlemen, it was great reading all the comments and suggestions. I wish to add a few lines too.

1. The sewage smell is no doubt is due to hydrogen sulphide gas, which is due too intense bacterial activity.

2. You can not get rid of the bacteria using bleach or chlorox. The continuous digestion of the food particles, oil and grease will release the gas.

3. Another possibility is that all the pipes are joined to a common septic tank. If this is the case, there is an anaerobic side and an aerobic side to the septic tank. If the aerobic side is not function properly, the gases tend to flow to the sink when the sink is not filled.

4. Look for dark blackish patches and deposition on the surface soil in and around the septic tanks and if you find any, then rest be assured its the design problem with the septic tank.

5. The solution is to look for a bacteria solution like EM or any other mix of anaerobic and aerobic bacteria. These are now-a-days available in the hardware and departmental stores.

6. Take app 50 ml and pour it down the sink and within 48 hours, the stuck food particles etc. will be digested and the odour will be gone.

7. You have to pour the aerobic bacteria solution on the aerobic side of the septic tank if this is causing the problem. Make sure the aerobic side is well vented to receive natural oxygen.

Sorry to post to such an old thread, but I would have started a new one with a similar title as I am having a similar problem. My house is about 4 years old and recently the 2nd sorry master bathroom sink has a problem with a sewer smell coming from the water. I have taken apart the trap to ensure it is clear, cleaned the plumbing by using baking soda and vinegar followed by boiling water and well as tried letting bleach sit in the trap for several hours and then flushed with boiling water and the problem persists. The sink has no overflow drain. I have put a small container under the faucet to collect the tap water to further rule out the drain and when the hot water is first turned on there is definitely a fairly strong sewer smell but the water itself does not smell after removing the container from the sink and smelling it. It's as if there are sewer gases that are being quickly released when the water is turned on and then quickly dissipating a few seconds after. I notice this smell every time the sink is unused for a little while and then hot water is ran. I can't say for sure if I smell the sewer smell coming from the cold water but if it is there the smell is much less than from the hot water. This problem only occurs at this one sink, none of the others sinks in the house have this problem. I've done a good deal of research on this and am at a loss what the problem could be. I was away on vacation for a few weeks last month so the houses plumbing as left unused but we have used the sink since and there is definitely water trap. I did have the hot water heater turned down a bit so perhaps bacteria could have formed in the water heater, but if this was the problem why would only the 2nd floor bathroom sink have this issue. I plan on draining the water heater soon anyway so I'm going to get the water to 140-160 degrees for a few hours before draining to kill off any bacteria that may be in the tank as a precaution. Any ideas on what would cause this problem coming from the water pipes and not the drain pipe and only on this one faucet?

To add to my previous post, I may have noticed this smell also coming from my outdoor hoses when I first turned them on. There water was also a milky white when I turned them on, but from what I have read online this sounds like just air coming out.

I found out that the smell comes right from below the sink, not from the trap. There is a dead spot at the connection of the sink and the drain pipe before the trap. Every time when the sewage smell occurs, there is a build-up of mucus at this dead spot. The only way to get rid of the smell is to pour some chlorox (1/4 of a cup) once a week into the sink and leave it for 5 minutes and flush it. In my case it works well with pouring chlorox every two weeks.

I'm also having this same problem. My recently renovated bathroom sink smells when the water is first turned on. The smell is mostly noticeable when I'm washing my face and my nose it close to the air vent holes towards the front of the sink. The water does not smell and the smell goes away quickly. However, the sink does not smell when not in use. I don't think it's a problem with the trap or the water. The shower and toilet do not smell. However I recently had a new dishwasher installed, and that does smell! The guy didn't place the tubing high enough to drain properly. We had a repair man check it out, and he wedged the tubing up high between the counter and kitchen sink, and it's helped, but it's still faintly stinky. Could this dishwasher be causing the smell upstairs at my bathroom sink?? I don't get this stuff. The smells are not the same. The bathroom is more sewer, and the dishwasher is more stagnant. I'm so annoyed by all of this! Probably they are two separate issues. I don't know.

We have been having the same problem for quite some time. However, the most overt smell is coming from our clothes wash machine, which is in the basement. I also smell an emission from the kitchen sink, and the up stairs bathroom sink. The smell can be very strong when we do a load of clothes for the first time after a break. I swear the smell is making me sick as well. I had air tests done, and had a plumber come. The air tests didn't indicate anything significant, and the "old" plumber walked through the house, sniffed at the sinks, and said he smelled a little, but didn't seem too concerned, and left. I recieved the $55 bill a few days later. My husband doesn't think it is that bad; however, our sons complain, and I swear my ears feel full, and I get light headed from it. I have poured the chlorax down the drains several times. Sometimes it seems as if that helps for a short time, but other times it does not. I am scared that if we do not figure this out there could be long term physical affects on us. Who else can I all in regard to this? I am SOO frustrated with this problem. People do not seem to take me serious about it.

If the smell is everywhere (bathroom sink, kitchen sink, washing machine) then it could be pressure building up in the sewer system which means a problem with the vent system of the sewer going to the roof. If it is a new house, the builder has to correct this vent system. It wasn't properly installed. The builder has to follow the Universal Plumbing Code.

If it is an existing house, then the vent pipe of the sewer system that vents above the roof is plugged with leaves or bird's nest. This obstruction needs to be removed.

if it is ascertained that the problem is not with plumbing and venting, then a good solution is to pour some Chlorox followed by any solution containing Aerobic bacteria. Bacterial solutions like EM Bacteria are available in the market. This should take care of the odour and the digestion of embedded food particles and other organic matter inside the pipes.

I gave up smoking cigarettes for vaping. No more carbon monixide and no more tars. I still get nicotine, but that is the least of a smoker's worries.

Anyway, as a youth I always had a very acute sense of smell. Since I started vaping, my sense of smell is coming back with a vengeance. The result? I've come to learn that the modern world, as a rule, doesn't smell very good. Woof!!!