How To Find The Sewer Trap And Locate Your House Sewer

Balkan University
May 31, 2013

by David Balkan

frsh air inlet
cover plate
Fresh air cover plate

Many people frequently have house sewer line or drain issues that get exasperated because they cannot find the sewer trap, and uncover their house drain. These issues can range from needing the drain cleaned to foul sewer smells and basement flooding.

There is a simple process to find the sewer trap and expose it before drain issues arise. This is something every home owner should take a few minutes to do before they are in a distressful situation.

The easiest way to find the sewer trap is to locate the fresh air inlet pipe which is typically located near the front wall of your house. On the outside front or side of your house it will be exposed and covered by a grating.

The grating on the fresh air inlet is usually around 9″ or 10″ wide and perforated in order to allow air to enter the system. In some cases the fresh air inlet for the house sewer will be a U shaped pipe pointing down at the sidewalk.

The fresh air inlet pipe itself is typically at least 3″ wide or 1/2 the size of the house drain, whichever is greater. Once you locate the fresh air inlet pipe inside your house you should be able to find the sewer trap on the street side of the inlet. It is illegal to have plumbing fixtures connected to a fresh air inlet although on occasion a house sewer may have such a connection.The fresh air inlet pipe is connected just behind the house trap and usually covered by a perforated plate on the outside of the foundation wall.

fresh air inlet
Vent located behind house trap
find sewer trap
U shaped vent pipe

There must always be ready access to the sewer trap and access pit. If it is permanently covered it cannot be accessed for cleaning or to check if the sewer trap is sealed properly. If the access pit or house trap is not sealed properly foul sewer gases and waste water can escape into the house. It can also become a source for rodent or insect infiltration.

Another important reason the access pit must be accessible is that frequently the water service line enters the house into the same pit and the main control valve for your water line will be in the pit. Having access to your main control valve is vitally important in case you have a water line emergency or leak inside the house.

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In some cases a homeowner or contractor may place flooring or concrete permanently over the access pit for the sewer trap. This is a mistake and must be removed immediately.

clogged pipe
Vent pipe blocked with grease

Another point about your fresh air inlet is that it helps waste water flow smoothly out of the drain system. It is as if you tried to drink out of a bottle and completely covered the opening not letting any air into the bottle. Your drink would come out in fits and bursts, no in an even flow.

Air is needed to displace the fluids that are flowing out or it will disrupt the flow of the water. This is also why when routine maintenance is required, always make sure that the fresh air inlet is also clear and unobstructed. The fresh air inlet cover plate should also be clear and not covered with leaves, dirt, or debris.

Why is a sewer trap so important?

Believe it or not a house trap on a sewer line is vitally important in many ways that you would probably never think of. That “thing” you see in the bottom of a pit in your basement can cause an awful lot of aggravation or damage if it is not functioning properly, is in poor condition, or is not operated properly.

Improper Or Missing Sewer Trap Plugs Or Caps

sewer trap
House trap with various plugs
  • Will allow noxious gases to escape into the premises from your sewer line.
  • Allow for rodents, insects, but not alligators, to enter into a premises.
  • Can allow raw sewage to enter into a premise if a back up occurs.

Trap plugs or caps cost around $10.00 or less each. They are made in at least three varieties, and are readily available from any plumbing supply or local hardware store. They are easily installed on a house sewer using basic household tools or can be installed by your plumber.

Whoever takes the time to install a new plug or cap will be paying a small price for preventing damage, inconvenience, and rodent or pest infestation. In addition this minor maintenance can prevent an unhealthy condition and noxious gases from entering in your property from your drain line.

Replacing missing or improper sewer trap plugs is another case where performing minor plumbing maintenance is well worth the effort.

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About Balkan Sewer And Water Main Service

sewer contractorBalkan is a family owned and operated NYC water main and sewer contractor trusted for over 65 years. Our website aids property owners and professionals alike on a daily basis. To learn more about your drain system read Know Your Drain Hardware. In addition online inquiries of all sorts are typically responded to within one hour with expert advice and information. We are dedicated to serving you in any way possible and guiding you through any water main or house sewer line issue you may have.

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David Balkan

David Balkan is the CEO of Balkan Sewer And Water Main, the largest and most trusted service in New York City. David is extremely active in various NYC plumber organizations being the Chairman of the Subsurface Committee in the Master Plumbers Council, and Vice President of the Subsurface Plumbers Association. In addition David’s expertise is respected by officials of New York City agencies such as the NYC DEP, NYC DOB, and the NYC DOT. He frequently provides valuable input on a variety of industry related matters.

Dave Balkan

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