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What is a Lateral Sewer?

Mary McMahon
Mary McMahon
Mary McMahon
Mary McMahon

A lateral sewer is a sewer which connects a structure to the main sewer line. Technically, a later sewer is not supposed to have any tributaries, but on a multifamily property, the lateral sewer may actually split to reach the plumbing of several different residences. The lateral sewer connects the indoor plumbing of a house with the sewer lines which carry waste away for treatment and processing.

Technically, the lateral sewer is the responsibility of the property owner. When someone constructs a new building, they must pay for connection to the sewer system, including placement of a lateral and the placement of meters to monitor usage. Monthly fees must also be paid, usually on the basis of how much water is routed into a structure, with the logic that what comes in must come out. However, once installed, the responsibility can become nebulous.

It is important to bleach any areas where raw sewage backed up.
It is important to bleach any areas where raw sewage backed up.

The issue is that while a lateral sewer belongs to the property, if a problem develops, it can become a public health issue. This means that sometimes officials may step in to address a problem, even though it is not their legal responsibility, in the interests of keeping people safe. In many communities, programs which pay for inspections of laterals and which will defray the costs of repairs are available. These programs ensure that issues such as breaks and blockages are addressed before they become a problem.

A sewer lateral is generally built to run downhill, so that gravity pulls the contents into the sewer main.
A sewer lateral is generally built to run downhill, so that gravity pulls the contents into the sewer main.

The most common problem which arises in the lateral is a blockage. Blockages are addressed by accessing the sewer clean out, a pipe which juts out of the lateral, usually just before it enters the structure. A snake and other devices can be put into the cleanout to clear the blockage and allow wastewater to run freely down the lateral. Leaks and breaks are another problem, especially in areas with cold weather, or when a lateral is broken by construction, digging for utility placement, and so forth.

The sewer lateral is generally designed to run downhill, so that gravity pulls the contents into the sewer main. This helps to reduce the risk of backflow, an undesirable situation in which raw sewage bubbles back up into household plumbing such as the shower. However, a blockage can force wastewater into the household plumbing because it has nowhere to go. When backflow occurs, it is important to bleach the area after the blockage has been cleared, as raw sewage can contain harmful microorganisms.

Mary McMahon
Mary McMahon

Ever since she began contributing to the site several years ago, Mary has embraced the exciting challenge of being a AboutMechanics researcher and writer. Mary has a liberal arts degree from Goddard College and spends her free time reading, cooking, and exploring the great outdoors.

Learn more...
Mary McMahon
Mary McMahon

Ever since she began contributing to the site several years ago, Mary has embraced the exciting challenge of being a AboutMechanics researcher and writer. Mary has a liberal arts degree from Goddard College and spends her free time reading, cooking, and exploring the great outdoors.

Learn more...

Discussion Comments

anon1002271

The councils are approving plastic breakable PVC in place of metal piping?

pastanaga

You know, I read in the paper recently that some city councils have managed to start making money off the gold they find in their sewers. Not just, for example, gold rings which have been lost down the drain, but gold dust that somehow got mixed up with the sludge.

I've heard that there are certain medications which use gold, so maybe that's partly where it is coming from, but they aren't really sure what accounts for it all.

Makes you wonder how much gold is leaving your house underneath your front walk every day. I'm not suggesting that you should go looking for it, of course! It's just a strange bit of trivia.

bythewell

@umbra21 - It's definitely something you want to ask about before you buy the house. Particularly in a built up urban area, where several houses might have been added to the same space in recent times, without upgrading the lateral sewer line, but just adding on to it.

If your house happens to be the one where the buck stops, you might get had up for damage caused by other properties, so absolutely make sure that's not going to be the case.

Also check to see what is the council's responsibility and how often you should be checking out this sewer to make sure it doesn't need maintenance.

I'm a big believer in fixing problems before they ever happen, particularly when it comes to sewerage.

umbra21

I didn't realize that the lateral sewer was legally the responsibility of the person who owns the house. Since it is a potential hazard, I would have thought it would fall under the responsibility of the local council.

I guess it makes sense for it to "belong" to the residence though, as if there is a blockage, it would originate with them, and likewise to most kinds of damage.

I guess how it usually works is that they swoop in and fix up the problem in order to mitigate any health issues and then charge the homeowner after the fact.

I'm kind of glad I found out about this as I'm planning to buy a house in the next couple of years, and it's the sort of thing I wouldn't have thought twice about.

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    • It is important to bleach any areas where raw sewage backed up.
      By: design56
      It is important to bleach any areas where raw sewage backed up.
    • A sewer lateral is generally built to run downhill, so that gravity pulls the contents into the sewer main.
      By: zonch
      A sewer lateral is generally built to run downhill, so that gravity pulls the contents into the sewer main.