Backed Up Sewer Line In Basement: 5 Causes And 3 Cures of Basement Backups

Water Main Service
October 9, 2017

by David Balkan

backed up sewer in basement

Backed up sewer line in basement problems are much more complicated to diagnose than one may think. First of all, the point of the back up frequently is not related to the point of the clog or pipe defect. Water under pressure, such as from a sewer back up, seeks the easiest and lowest point to escape. That is why waste water backing up from a basement sewer line frequently appears out of a floor drain, or the main house trap. That is even though neither is usually the point of the defect.

The 5 Main Causes Of Backed Up A Sewer Line In Basements

When a backed up sewer line in basement situation occurs, it can be from numerous causes. It typically takes a professional to figure out the root cause. In addition, a novice searching for the cause of a basement sewer back up, or water coming up through basement floor drain after heavy rain, can frequently exasperate the situation.

Tampering with any piece of plumbing without the proper knowledge usually leads to trouble, and drain lines are no different. What follows are the 5 main culprits that cause backups in a basement. Another great thing to know is that there are sewer alarms, and water sensor alarms. These relatively inexpensive alrams warn you of an issue before the issue creates damage or surfaces above your basement floor.

1. Wash tub basin back ups

diagram of a wash tub basin trap and how it functions
Typical sink or wash tub basin trap

A back up out of a wash tub basin usually means the strainer is clogged and needs to be cleaned. This is a case where a homeowner can do it themselves. If you do not already have a strainer on the drain inlet, install one. In other cases sediment and debris may have clogged the trap under the basin. You can try a plunger, but you may need additional help.

Frequently a trap clog requires an electric snake, or for the trap to be removed and cleaned by hand. It’s usually best to hire a pro for these “seemingly” easy chores.

In some cases a wash tub basin back up is a sign of something more serious. If the basin is the lowest plumbing fixture in your basement, then it is the easiest way for backed up sewer water to escape. In those cases the clog or defect may be further down the line in your drain system. This becomes another case where the cause of backed up sewer line in basement drains, doesn’t match the obvious appearance.

2. Washing machine back ups

Washing machines can sometimes back up, and this can involve a large volume of water. The first step is to shut off the machine, and not panic. In many cases a strainer on the drain hose may have become clogged. That is an easy fix. A drain hose can be connected into a wash tub basin, or a branch line drain. If either is backed up, revert back to the paragraph above. In all likelihood it is a trap stoppage.

3. Floor drain back ups and sewer smells

A floor drain back up in your basement is almost never due to the floor drain. That is because most floor drains rarely take in any water, the usual problem is the opposite. That is to say, the drain and trap dry out, then let in sewer gases. The cure for that is simply dumping some clean water into the drain to refill the trap. Floor drain issues are cause of a backed up sewer line in basement due to their infreuqent use, and infrequent required maintenance as well.

When water is backing up out of your floor drain, the causes are many. It typically means the house drain under your basement floor is full of water. That can frequently mean a rainstorm has surcharged the drain system, or even the public sewer system. If that is defined as the cause, you may consider installing a sewer valve to prevent backwater surcharges.

In other cases, a basement floor drain backing up when kitchen sink drains, or a toilet is flushed can mean a drain stoppage further down the line. If there hasn’t been a recent heavy rain, then there is probably a main line clog. A main line clog can be in the house drain, house trap, or house sewer. In any case, always call a professional who has an array to tools and the expertise to figure it all out.

4. House sewer trap clogs and seepage

double vent main house trap with a description of how it functions
Main house sewer double vent trap

A backed up sewer line in basement is probabley most frequently caused by a main house trap issue. Water emanating from your house trap must be dealt with carefully. Do not just randomly start removing the plugs on your main house trap. That can truly lead to a drain disaster. For instance, removing the street side plug when the public sewer sewer is backed up will quickly introduce all that city sewer waste water into your basement. And after you remove that plug, it is unlikely you will be able to put it back on.

The simplest sewer trap back up to cure is when the trap itself is clogged. That is cured by opening the street side plug, then the house side plug. This is done to allow any sewer water backed up under the basement floor to escape over the trap itself. Then the belly of the trap (the bottom of the U shape of the trap) can be cleared out. Again, this is task best left to a professional to avoid a flood of sewer water.

In other cases there may be a clog down the line from the main house sewer. In yet other cases the trap itself may be worn. The sewer trap may have to be replaced, or the plugs replaced. A “quick fix” handyman special usually is just a waste of time, and frequently results in sewer gases escaping into your home.

5. Basement showers, bathtubs, or toilet backups

A backed up sewer line in basement first becomes visually apparent from low lying plumbing fixtures. So again, a tub, shower, or toilet in your basement may be the first place you see a back up, but not the cause itself.  Resist trying to play around with delicate plumbing fixtures unless you are absolutely 100% sure they are clogged. Just like a basement floor drain, the root culprit of the clog is probably further down in your drain system.

How Do You Unclog A Backup Up Sewer Line In Basement?

There are several ways to cure backed up sewer line in basement issues. The usual first step is a visual inspection by a sewer and drain professional. The next step is then to run an electric sewer snake down the clogged drain line.

In some cases a HD sewer camera can pinpoint the cause, and the exact location of the problem. Only in rare cases is a sewer drain line repair needed. But in those cases, trust a licensed drain line repair professional.

In many cases a high pressure water jet can clear out stubborn clogs. A water jet is particularly successful in clearing out grease stoppages. Grease stoppages can accumulate and harden inside of pipes over a prolonged period of time.

backed up sewer line in basement filled with accumulated grease
Grease blocked main house drain

3 Steps To Prevent A Backed Up Sewer Line In Basement

There are a few ways to prevent basement back ups. Each serves to address a particular issue, none is a “cure all”. Before making a hiring decision, make 100% sure you know the true cause of your drain problems.

To help ensure a sure-fire and correct cure, it is advisable to contact a Licensed Plumber. Always keep in in mind that if you live in the NYC area, Balkan provides free site visits 7 days a week, and after hours as well. Online is also always available via our website.

1. Routine maintenance

If you have periodic back ups routine maintenance by a drain cleaning professional is a great idea. A maintenance program can be pre-scheduled annually before you have a problem. In addition, it is always at a discounted rate to a “one time” emergency call.

2. A water tight house sewer trap

A water tight sewer house trap with tight fitting plugs is a vital key to keeping a dry basement. Sewer traps do become worn over the years, especially if you’ve had frequent sewer back ups and cleanings. Even more frequently the plugs become worn and ill fitting. Click this link to learn even more about your sewer trap.

broken main sewer trap with the sewer trap plugs missing
A broken and worn house sewer trap

3. Sewer valves: Best prevention for backed up sewer lines in basement

If you suffer from basement sewer back ups during heavy rain, or city sewer surcharges, a sewer valve may the ideal long term solution. In the field of sewer valve installations, Balkan is the expert in NYC. Sewer valves come in a variety of styles, for a variety of applications.

To learn more about sewer backwater valves, read a full report about sewer valves. The cost of installing a sewer check valve, or automatic sewer flood gate valve, is typically much less than the damage from one sewer surcharge entering your basement.

If you need expert advice or s site visit, contact Balkan Sewer And Water Main Service. All site visits are free, and without any obligation to hire us. After hour and weekend site visits are also available.

inside of a cast iron sewer check with a brass flapper
A basic sewer check valve is a very simple device

About Balkan Sewer And Water Main Service

The Balkan Team provides expert sewer and water main repairs and replacements. We are experts in all types of NYC underground plumbing. Balkan Sewer And Water Main Service was founded in 1952. Since its inception, the foundation of the company has been based upon integrity and honesty in all of our dealings. That solid foundation has enabled us to thrive in every economic climate.

The year 2022 actually marked our 70th consecutive year in business. As we have grown, we have become increasingly dependent upon a “Team First” approach.

A Team First Approach Ensures High Standards

What helps ensure a continuation of our high standards, overall integrity, and high company morale, is that same team approach. Complete client satisfaction has always been the number one goal at Balkan Sewer And Water Main. That is why we are NYC’s largest and most trusted sewer and water main service in New York City. Simply put, if it’s plumbing, and it’s underground, we do it. For over 70 years, and for over 90,000 New Yorkers to date, Balkan is “The Team You Trust”.

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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.

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