You smell something in the bathroom. Or is it coming from the toilet? A few minutes later it seems to be gone. So you walk around the house again and, just to be sure, sniff the shower drain. The annoying thing about a sewer smell is that you usually cannot see where it is coming from. Sometimes it is as simple as a dry water trap. Sometimes the problem is further down the drain or sewer pipe. First find the cause. Then fix it.
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What does a sewer or drain smell in your home usually mean?
A sewer smell, sewage smell or bad drain smell usually means that air from the drainage system or sewer can enter your home. In Dutch, this unpleasant smell is often described as putlucht.
A dry or dirty water trap is one of the simpler causes. If the water also drains slowly or you hear gurgling sounds, there may be a blockage. If you notice the smell in several rooms or it keeps returning, the problem may be further down the drainage system or related to sewer ventilation.
Bad smell from one rarely used drain?
First check whether the water trap is still filled with water.
Bad drain smell and slow-draining water?
A blockage becomes more likely. You can then have the drain unblocked.
Sewer smell and several gurgling drains?
The problem may be further down the drainage system. In that case, sewer unblocking may be the appropriate job.
Sewer smell coming from the floor or crawl space?
Check for moisture, standing water or a leaking drain pipe.
Still cannot work out where the smell is coming from? You do not need to start replacing traps, pipes and drains one by one. Have a plumber investigate the cause first.
Have a plumber investigate the sewer smell →
How can you tell where the sewer smell is coming from?
Where you smell it provides a clue. When you smell it can tell you even more.
Sewer smell in the bathroom
If your bathroom smells like a sewer, start with the shower drain, washbasin and any floor drains. A dry water trap, dirt in the shower drain or a dirty siphon are logical first suspects.
Does the smell mainly appear during or after showering and is the shower water also draining slowly? First remove visible hair and dirt. If that does not solve the problem, you can have the shower drain professionally unblocked.
If another drain starts gurgling at the same time, the problem may be further down the drainage system.
Sewer smell near the toilet
A bad smell around the toilet can come from a nearby drain, but it can also come from the toilet connection itself. A connection that no longer seals properly may allow sewer smells into the room even when there is no obvious water leak.
Bad smell from the kitchen sink or washbasin
If the smell is clearly strongest around one sink, check the siphon or P-trap underneath it.
That curved section of pipe is not there for decoration. Water remains inside it and creates a barrier between your home and the sewer.
If the siphon is cracked, damaged or no longer seals properly, it may need to be replaced. Zoofy has a separate service for installing or replacing a siphon.
Sewer smell and a gurgling drain
A gurgling drain is an important clue. Especially when it happens after flushing the toilet, when the washing machine pumps out water or when a large amount of water disappears down another drain.
It can indicate a restriction, blockage or ventilation problem in the drainage system.
Sewer smell after a holiday
Come home after a few weeks away and suddenly find that the bathroom smells like sewage?
Do not immediately assume you need major sewer work.
A trap or floor drain that has not been used for a while may simply have dried out.
Add water.
Wait a little.
Sometimes that was the entire problem.
Sewer smell in several parts of the house
If you notice the smell in the bathroom, around the toilet and downstairs as well, one dirty siphon becomes less likely.
The cause may be further down the drainage system, in the main sewer pipe or in the sewer ventilation.
When several drains are affected, have the sewer checked for a blockage rather than treating every drain separately.
Sewer smell coming from the crawl space
If the smell seems strongest close to the floor and you cannot find an obvious source inside the home, include the crawl space in your checks.
A leaking waste or sewer pipe can release unpleasant smells underneath the house. Standing water and other moisture problems can also create strong odours.
If you can see a leak, you can book crawl-space leak repair. If there is standing water but you do not yet know why, see water in the crawl space.
What causes a sewer smell in your home?
1. A dry water trap or P-trap
This is one of the simplest causes of a sewer smell in the home.
Under sinks and washbasins you usually have a siphon or P-trap. Shower drains and floor drains also normally contain a water trap. A small amount of water deliberately remains inside it, creating a barrier against smells from the sewer.
If a drain is not used for a long time, that water can evaporate.
The drain is still open.
The smell barrier has simply left.
How to recognise it: the smell comes from one rarely used drain and disappears after running water through it.
What you can do: run enough water through the drain to refill the trap and check later whether the smell stays away.
If the siphon itself is damaged rather than dry, read more about the cost of replacing a siphon.
2. A dirty siphon or P-trap
A siphon keeps sewer smells out, but it also collects soap, grease, hair and other debris.
That dirt can start to smell all by itself.
How to recognise it: the smell is strongest directly above the sink or washbasin and the water may also be draining more slowly.
What you can do: carefully clean an easily accessible siphon yourself. Put a bucket underneath before removing it.
If cleaning does not help and the siphon is damaged, a plumber can install a new siphon.
3. A damaged water trap or leaking connection
A small crack in a siphon, worn seal or poorly fitted connection can be enough to let sewer air escape.
You will not necessarily see water leaking.
How to recognise it: the smell keeps returning in exactly the same place even after filling and cleaning the trap.
What you can do: check visible connections for cracks, moisture or loose fittings. If the drain itself is leaking, have the leaking drain repaired.
4. A blocked drain
Hair, soap, grease and food waste can gradually build up inside a drain. The pipe does not have to be completely blocked before you notice something.
First the water drains a little more slowly.
Then you hear some gurgling.
And one day your kitchen smells as though someone has opened a miniature sewer underneath the sink.
How to recognise it: water drains slowly, the pipe gurgles and the bad smell clearly seems to come from that drain.
What you can do: remove visible debris and clean an accessible siphon. If the water still drains poorly, have the drain unblocked.
Does the problem mainly concern the kitchen sink? You can also read more about the cost of unclogging a sink.
5. A blockage further down the sewer line
Are several drains having problems at the same time? The blockage may be further down the system.
You may notice that the shower gurgles when you flush the toilet, that several fixtures drain slowly or that water rises through another drain.
At that point, cleaning the shower drain for the fourth time is probably not going to solve much.
What you can do: have the sewer blockage cleared.
If the blockage keeps returning or its location is unclear, a sewer camera inspection can help determine what is happening inside the pipe.
6. Problems with sewer ventilation
Water is not the only thing moving through a drainage system. Air also needs somewhere to go.
That is why sewer systems need ventilation. In many homes, a vent pipe runs upwards and eventually exits through the roof.
If the ventilation does not work properly or pressure changes develop inside the drainage system, water can be pulled out of a trap. The barrier against sewer smells then becomes too low or disappears completely.
How to recognise it: several drains gurgle or the sewer smell appears shortly after flushing the toilet or draining a large amount of water.
What you can do: have the drainage and ventilation assessed. If a new or improved vent is required, Zoofy has a specific service to install sewer ventilation.
7. A damaged sewer or drain pipe
A poor connection, crack, displaced pipe or damaged seal can allow sewer smells to escape.
The source may be behind a wall, underneath the floor or inside the crawl space.
How to recognise it: the smell does not clearly come from one drain and remains even after cleaning and refilling the water traps.
What you can do: have the pipe investigated. If the problem is hidden, a sewer inspection with camera may help locate damage or recurring blockages.
8. Water or a leak in the crawl space
The crawl space is worth checking when you cannot find the source of the smell anywhere inside the home.
If there is standing water beneath the property or a drain pipe is damaged, smells can enter the house through gaps and openings around pipework.
If there is a visible leak, book Leakage crawl space.
If the main problem is standing water and the source is not yet clear, choose Water in crawl space.
How can you check where the sewer smell is coming from yourself?
You do not need to start taking pipes apart.
Your nose, ears and a few taps can tell you quite a lot.
1. Find where the smell is strongest.
Check shower drains, washbasins, kitchen sinks, toilets and floor drains. Do not forget a utility room, garage or second bathroom that is rarely used.
2. Refill all water traps.
Run water through drains that are not used very often. Add water to a floor drain or shower in a guest bathroom as well.
3. Check how quickly the water drains.
Turn on the taps and compare the drains. A drain that is clearly slower than the others may be partially blocked.
4. Listen for gurgling.
Flush the toilet. Fill and empty the washbasin. Do you hear another drain gurgling? Remember which one.
5. Check the siphon and visible connections.
Can you see moisture, dirt marks or a crack? Is the smell much stronger underneath the sink than above it? That gives you another clue.
6. Notice when the sewer smell appears.
After showering? After flushing the toilet? When the washing machine pumps out? Only in the morning? Or after you have been away for a few weeks?
7. Check near the crawl-space hatch.
Can you clearly see or smell moisture, standing water or sewage there? Do not enter a poorly ventilated crawl space yourself when there is a very strong unexplained smell.
Still cannot determine where the smell is coming from?
Then the job is not to pour something else down the drain.
The job is to find the cause.
Have a plumber investigate the cause →
What should you do now about a sewer or drain smell?
The smell comes from a rarely used drain
Run plenty of water through it. Then check whether the smell disappears and stays away.
The siphon or shower drain is dirty
Remove hair and visible dirt. You can usually clean an easily accessible siphon yourself.
If the shower drain remains blocked or smells bad after cleaning, have the shower drain unblocked.
The water is draining slowly
There is probably more going on than just a smell. Clean the accessible parts first. If the water continues to drain slowly, have the drain professionally unblocked.
Several drains are gurgling
Stop treating each drain as a separate problem.
The chance increases that the cause is further down the sewer system. In that situation, choose Unclog sewer.
The sewer smell keeps coming back
An air freshener may temporarily make the house smell like citrus instead of sewage.
The sewer will not be particularly impressed.
Have the underlying cause investigated.
Sewer smell in your home: what can you do yourself and what should you leave to a plumber?
What you can do yourself
Refill a dry water trap with water.
Remove hair and visible debris from a shower drain.
Clean an easily accessible siphon.
Check whether water drains normally.
Listen for gurgling from other drains.
Work out when the sewer smell appears.
Check visible connections for leaks or damage.
Was a dry water trap the problem and has the smell disappeared?
Good.
That was the easy version.
When does it become too complicated?
Once you need to dismantle pipework, the suspected cause is behind a wall or underneath the floor, several drains are affected at the same time or you simply cannot work out where the smell comes from, you have reached the end of the sensible DIY section.
Climbing onto the roof to inspect the sewer vent is not a particularly sensible next step for your Saturday afternoon either.
You can keep looking, of course.
At some point you are mostly becoming very good at smelling drains.
What should you leave to a plumber?
A plumber can determine whether the sewer smell is caused by a blockage, leaking connection, damaged siphon, ventilation problem or damaged sewer pipe.
If you do not yet know which of these applies, book a plumber per hour and describe the symptoms in the booking form.
Already know that the drain itself is blocked? Book Unclog drain instead.
Have a plumber investigate the problem →
When should you call a plumber quickly?
A slight drain smell from a dry trap is very different from a house where the sewer smell keeps getting stronger.
Have the problem checked quickly when:
the sewer smell is strong and does not disappear;
the smell keeps returning;
several drains are gurgling at the same time;
water rises through another drain;
sewage backs up into your home;
you see leaking or contaminated water in the crawl space;
you suspect a damaged sewer pipe;
you cannot determine where a strong smell is coming from.
If several drains are backing up or gurgling, have the sewer blockage dealt with.
If the problem keeps returning and nobody can see where it originates, book a sewer camera inspection.
Is a sewer smell dangerous?
A sewer smell can have different causes, and smell alone does not tell you exactly which gases are present or in what concentration.
A strong, persistent or unexplained smell in a small or poorly ventilated space should therefore be taken seriously. Ventilate where it is safe to do so and do not enter a poorly ventilated crawl space yourself to search for the source.
If you feel unwell, become dizzy, nauseous or short of breath, leave the area and seek medical assistance if necessary.
Bad smell in your home, but not from the sewer?
Not every unpleasant smell is a sewer problem.
Musty smell:
Moisture, poor ventilation or mould are more likely.
Rotting smell:
Check whether food, rubbish or possibly a dead animal could be the cause.
Smell from the crawl space:
As well as a leaking sewer pipe, consider standing water, moisture or other contamination underneath the house.
Burning or melting-plastic smell:
That does not fit a normal drainage problem. Stop looking for a blocked sewer and investigate the electrical source instead.
Clear gas smell:
Do not treat this as normal sewer or drain odour. Follow the appropriate gas-leak safety procedure instead.
The important question is therefore not only how unpleasant the smell is.
It is where it comes from and what else is happening in your home at the same time.
Which plumbing service do you need for a sewer smell?
You smell sewage but have no idea where it comes from
Book a plumber per hour. Explain where you notice the smell, when it occurs and which checks you have already carried out.
One sink or drain smells and drains slowly
Choose Unclog drain.
The shower drain smells and the water stays around your feet
Choose Unclog shower drain.
The siphon is leaking or damaged
A damaged siphon may no longer create a proper water and odour seal. Book Install siphon.
The drain connection itself is leaking
Choose Leaky drain.
Several drains gurgle, drain badly or smell
The problem may be deeper in the system. Choose Unclog sewer.
The sewer smell keeps returning and the cause remains unclear
A sewer inspection with camera can help identify blockages, cracks or other problems further down the pipe.
The problem appears to be sewer ventilation
If traps repeatedly lose water and several drains gurgle, sewer ventilation may need to be assessed. If additional ventilation is required, book Install sewer ventilation.
You see a leak in the crawl space
Choose Leakage crawl space.
There is standing water in the crawl space
Choose Water in crawl space.
How does a plumber solve a sewer or drain smell?
The correct solution depends on the cause. That is why the plumber first investigates before replacing or opening anything unnecessarily.
1. Locate the problem
Where is the smell strongest? Which drains are affected? When does it occur?
2. Determine the cause
The plumber checks the siphons, visible connections, drainage and flow through the pipe.
3. Investigate further if necessary
If the cause is not visible, a camera inspection of the sewer may be used to inspect the inside of the pipe.
4. Repair or unblock
Depending on the cause, the plumber may unblock a drain, replace a siphon, repair a leaking drain, clear a deeper sewer blockage or deal with the ventilation system.
5. Check the result
Finally, the plumber checks whether the water flows properly again and whether the original problem has disappeared.
Not just the smell.
The reason it was there in the first place.
What happens if you do nothing about a sewer smell?
That depends on the cause.
There is usually nothing dramatic about a dry water trap. Refill it and the problem may be solved immediately.
Other causes are less enthusiastic about fixing themselves.
A partial blockage
Water may drain increasingly slowly until the pipe eventually becomes completely blocked. If you recognise this, have the drain unblocked before it becomes a complete blockage.
A deeper sewer blockage
Several drains may eventually stop working properly or wastewater may begin to flow back. In that situation, have the sewer blockage cleared.
A ventilation problem
Water may repeatedly be pulled from traps, allowing the sewer smell to keep returning. Have the system checked and, where necessary, improve the sewer ventilation.
A leaking drain or sewer pipe
Moisture and contamination can spread underneath the floor or through the crawl space. A visible leaking drain can be repaired by a plumber.
Water in the crawl space
Long-term moisture can create additional damp-related problems. Find out more about removing water from the crawl space.
No reason to leave the house the first time you notice a strange smell.
But also no reason to make a smell that has been returning for weeks part of the home's natural fragrance.
How can you prevent sewer and drain smells?
Run water occasionally through sinks, showers and floor drains that are rarely used.
Regularly remove hair and dirt from shower drains.
Clean the siphon when you notice that water is starting to drain more slowly.
Do not pour cooking oil, grease or food scraps down the sink.
Use a drain strainer to catch hair and food waste.
Do not ignore repeated gurgling from drains.
Have recurring blockages investigated instead of simply unblocking the same pipe again and again.
Deal with leaks and standing water in the crawl space.
Want to do more yourself to prevent blocked pipes? Read how to clean your drains and sewage system.
Does the same blockage keep returning despite cleaning? Do not keep treating the symptom. A sewer camera inspection can help identify an underlying problem.
What do customers say about drain problems?
A sewer smell is a symptom and can have several causes. That is why not every sewer smell should automatically be booked as the same type of job.
When a blocked drain is the cause, customers currently rate Unclog drain 4.7 out of 5 stars.
Reviews from real jobs completed through Zoofy's selected professionals show that customers especially appreciate quick diagnosis, clear communication, tidy work and checking that the drain flows properly again before the professional leaves.
One recent English-language customer review mentions that the plumber arrived punctually, cleared the blockage quickly and thoroughly and cleaned everything before leaving.
Other customers mention getting useful advice about preventing another blockage.
That is exactly what you want when a sewer smell keeps returning.
Not only that the smell disappears.
But that you understand why it was there.
How much does it cost to fix a sewer smell in your home?
There is no single price for “fixing a sewer smell”. The smell is the symptom. The price depends on the underlying cause.
You do not know the cause yet:
A plumber per hour is available through Zoofy from €75 per hour including VAT.
One drain is blocked:
You can book Unclog drain from €109 including VAT.
The blockage is further down the sewer:
You can book Unclog sewer from €199 including VAT.
A camera inspection is required:
A sewer inspection with camera is available from €199 including VAT.
The siphon needs to be replaced:
The price depends largely on the type of siphon and how easy it is to reach. See the cost guide for replacing a siphon.
You have a sewer blockage:
For a broader overview of costs and the factors that affect the price, read the Zoofy guide to the costs of unclogging sewers.
The kitchen sink is blocked:
See the separate guide to the cost of unclogging a sink.
Frequently asked questions about sewer and drain smells
Why does my house suddenly smell like sewage?
First check the water traps in rarely used sinks, showers and floor drains. If they still contain water, check whether a drain is slow or gurgling. If the sewer smell remains, there may be a problem further down the drainage system.
What does the Dutch word "putlucht" mean?
Putlucht is commonly used in Dutch for an unpleasant sewer-like or drain smell. If someone says there is putlucht in huis, they usually mean they can smell something coming from a drain or sewer system inside the home.
Where does a sewer smell in the house come from?
The smell often enters through a drain. Common causes include a dry or damaged water trap, dirty siphon, blocked drain, sewer ventilation problem or a damaged pipe connection.
Why does my bathroom smell like sewage?
Start with the shower drain and washbasin siphon. If the shower drain also drains slowly, you may need to have the shower drain unblocked. If other drains gurgle at the same time, the problem may be deeper in the sewer system.
Why does my shower drain smell like sewage?
A dry water trap, accumulated hair and dirt or a blockage further down the drain are common causes. First refill the water trap and clean the accessible part of the shower drain. If this does not work, book a plumber to unblock the shower drain.
Why does my toilet area smell like sewage?
The smell may come from a nearby drain, but the toilet connection itself may also no longer seal properly. If the smell is strongest directly around the toilet while other drains work normally, have the connection inspected.
Why does my house smell like sewage after a holiday?
A rarely used siphon or floor drain may have dried out while you were away. Run water through all drains first. If the smell disappears and stays away, a dry water trap was probably the cause.
Why do my drains gurgle and smell?
Gurgling combined with sewer smells can indicate a blockage or a problem with air movement inside the drainage system. If several drains are affected, have the sewer checked for a blockage. If the problem is related to ventilation, a plumber can assess whether sewer ventilation needs to be improved.
Can a sewer smell come from the crawl space?
Yes. A leaking or damaged waste or sewer pipe underneath the house can release smells. If you see leakage, choose Leakage crawl space. If there is standing water underneath the house, see Water in crawl space.
Can I get rid of a sewer smell myself?
You can usually refill a dry water trap, clean a shower drain or clean an accessible siphon yourself. If the smell returns, several drains are affected or you cannot find the source, book a plumber to investigate the problem.
When do I need a sewer camera inspection?
A camera inspection is particularly useful when a sewer problem keeps returning, the blockage cannot be located easily or there may be damage further inside the pipe. In that case you can book a sewer inspection with camera.
Does the sewer smell keep coming back? Find the cause
You have run water through all the traps.
Cleaned the shower drain.
Looked underneath the kitchen sink.
Had one more sniff.
And there it is again.
Time to stop guessing.
If you do not know where the smell is coming from, book a plumber per hour through Zoofy to investigate the problem.
Already know that one drain is blocked? Choose Unclog drain.
Are several drains affected or is the blockage further down the sewer? Choose Unclog sewer.
Does the problem keep returning and nobody can see why? A sewer camera inspection may be the logical next step.
Through Zoofy, you choose the job and preferred time. Zoofy arranges a screened professional and you pay Zoofy securely after the job is completed.
Then your home can go back to smelling like your home.
Much better.
Have a plumber investigate the sewer smell →
So. Sorted.
My name is Wilm, a construction and home improvement expert at Zoofy, with many years of experience in the construction and renovation sector. Over the years, I have supervised countless projects, ranging from small maintenance jobs to full-scale renovations. This hands-on experience has taught me how essential transparency in pricing and quality is for every project.
At Zoofy, I share my knowledge about construction costs, pricing, and smartly comparing jobs. Whether it’s the cost of a painter, a plumber’s hourly rate, or the price of a complete bathroom renovation, I help you understand what a fair price is and what to look out for.
My goal is to make home improvement projects more transparent, so everyone knows where their money goes. By combining up-to-date pricing information with real-world experience, I make it easier to find the right professional—without any surprises afterward.