Why Does My House Smell Like Sewer At Night

Why Does My House Smell Like Sewer at Night? | 7 Possible Reasons!

Your house smelling like sewer at night can drive you nuts and rob you of your hard-earned sleep! This can be even more bothersome if the stench keeps occurring every other night and won’t give you a break. Prompting the question…

Why does my house smell like sewer at night?

Some of the top reasons for sewer smell at night may be due to a broken drainage pipe, a cracked vent stack, a clog, a problem with your septic tank, and many more.

So, what does this mean for you?

See how I have explained all these below…

Why Does Your House Smell Like Sewer at Night?

1. Leaky or Broken Toilets

If your toilet seat has a loose bolt at the base where it’s fastened onto the floor, it can let sewer gases into the house.

Sometimes, the smell may not directly come from the sewage leaking onto the floor or walls. Sometimes the smell comes when the leaking sewer waste pools in crevices around your toilet.

When this happens, it attracts bacteria that would thrive in the present condition and give off the wretched sewer smell as they break down the waste hidden around your toilet.

2. Cracked Vent Stack

Man Is Fixing Home Ventilation

A vent stack runs from the major drainage waste pipes and is normally installed vertically (in or against a wall) through the house’s roof.

This easy-to-spot structure is normally attached to the main drains running horizontally below your house and helps to release the sewer gases into the atmosphere above. But things can go wrong and sewage smell can come out of air vents.

In the unfortunate event that this vent cracks or breaks in any manner, then the strong sewer stench will eventually fill your house as the gases leak from the pipes.

To avoid getting into such a fix, you should ensure that your stack is glued probably during installation or in case of a crack.

3. Blocked Drains

Blocked drains prevent liquid waste from effectively leaving your house into the septic or municipal drainage system.

When such blockage occurs, a lot of the waste will clog up your house’s drain pipes as they would have nowhere else to go.

The endgame is that pressure might build up and cause the foul gases to force their way through the solid waste and come into your house as sewage gas backup.

On the other hand…

This backup can also result in your washing machine smelling like sewage. The chances of this happening are also very high if you constantly flush soap bars and hair down your drains.


Well, most soaps are antibacterial and will either kill or slow the break-down process of organic waste by the good bacteria. On the other side of the track, hair is also very difficult to digest. (Especially if they’re synthetic)

4. Malfunctioning Septic Tank

Septic Tank 1

This is also a possibility, but a less likely reason for that nasty sewer smell at night.

You should avoid things that clog septic tanks such as paint (and thinners!), diapers, tampons, oil, grease, etc. When flushed down any of your house’s drains, these harmful things will cause the septic tank to malfunction by disrupting the digestion process of the bacteria.

As a result, solid waste may rapidly start building up in the tank, continuously restricting the volume of waste that can be collected in your septic unit.

When this happens, there will be an inevitable backflow from the sewer lines into your house – bringing with it the bad, sewer smell.

5. Dry P-Trap

A P-trap’s function is to prevent awful smells and odors from the sewage drain from coming into the house. The P-trap pipe usually comes in a U-shape and is designed to hold some water at the base of the “U” shape.

The accumulated water in the pipe acts as an effective barrier that prevents sewer gases from moving from the internal drain into your house’s living space.

If the smell of sewer at night is coming from your bathroom, then chances are that your bathroom’s P-trap may have dried out. There isn’t any barrier present and so the sewer gases are easily moving from the waste pipes back into your bath drains.

6. Water Pressure

Sometimes, the fluid pressure found in the sewage lines may go high. This can be a result of an increase in the volume of fluid that passes through the pipes.

The increase, normally, might be due to a recent heavy downpour, melting snow, or even a backflow from the septic.

Should it happen, the pipes may crack and leak sewage into your house through the walls or other porous surfaces, resulting in the foul odor that you smell at night.


7. Faulty Plumbing

Faulty plumbing entails using wrong-sized links to connect drainage pipes around your house. This mistake can easily lead to sewage leaking into your house because of the incompatibility of the pipes.

The other common mistake that we frequently see in plumbing is using a bad wax sealant when linking the drain pipes together.

As it’s quite obvious, the flawed sealant will slowly give in to the pressure from the constantly moving sewer loads in the drain pipes. Eventually, you’ll have to deal with a terrible, hidden leak that spews awful sewer stench all over your house.

What To Do if Your House Smells Like Sewer at Night?

Here are some helpful tips that you should consider following if you want to tackle the sewer smell coming into your house at night:

  • Make sure that you regularly use your showers or bathroom utilities to prevent the P-trap from drying up. You can also turn on the water and let it run for a short while in the rarely used rooms.
  • Ensure that you use only the best, verified wax seals when doing the initial plumbing or repairs for your house’s drainage.
  • You can use caulk on cracks and leaks when you want to re-seal broken links in the piping or fasten a fidgety toilet seat.
  • In case of leaves or snowfall blocking your vent stack, then removing the blockage should do the trick.
  • In case of sewage backup, act fast and clean up the mess using approved disinfectants. Ensure that you get every corner and crevice as you move!
  • Use a drain snake to clear away any clog that might have built up in the sewer pipes.

If you follow the above tips and still make no headway, then I suggest that you contact a professional plumber!

They are well-versed with house drainage systems and are better equipped to make an accurate diagnosis of the problem.

Frequently Asked Questions

1. What is the best way of getting rid of a clog?

Woman With Plunger Is Removing Clog In The Sink

A drain snake should be your first line of defense when dealing with a clogged pipe.

The best thing about it all is that you can snake drain yourself and save on costs that you would’ve incurred if you reached for external help.

2. How can I find the source of the sewer smell in my home?

You should always start with the water drains around your household.

This is because a high percentage of sewage smell will always come from your drainage system.

You can start by checking out your toilets, tubs, showers, and skinks for any signs of liquid or sewage gas leakage.