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Under Slab Sewer Line & Plumbing Repair & Replacement Cost

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Ask any homeowner about what is the most common issue they have at home, and they would more than likely point to a problem involving their plumbing system.

It may be a leak or two that keeps them up at night, clogged sinks that makes them unproductive in the kitchen, broken drain pipes that cause the entire home to stink, or rusted components that need replacing… the plumbing issues are just so many!

But, all those can be considered minor when compared to having a broken sewer line found under a concrete slab.

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Most plumbing issues can be easily fixed, or even solved through DIY means, because there is easy access to the problematic sections. It is very easy to remove and replace damaged pipes, or even do minor fixes without having them removed at all.

This is not the case when the issue lies with your sewer line found underneath a cement slab. All that hardened concrete covers up your pipes, and accessing them will be challenging.

Broken sewer line

Consider yourself lucky if the damage to your sewer line happens somewhere outside your home, as it would be a lot harder to deal indoors. Not only does the plumber have to work around your basement, your home will also be immediately affected by it, especially if the sewage seeps out of the floor.

If you got here because this is a problem you are facing, you should know that all hope is not lost – you can definitely get it fixed. Just continue reading to find out how.

Signs Indicating the Need to Replace the Sewer Line

Plumbing issues are always complicated. Unless you are dealing with an obvious and visible leak, determining the problem and the source of it all involves a lot of guesswork. You might think that there is just a simple blockage along your pipes, but it may actually be because your pipes are starting to give due to their age.

Finding out if the problem lies somewhere along the sewer line is going to be a bit more challenging. This is because some indicators are similar to common issues that plague plumbing systems, especially the pipes.

But in any case, you should get in touch with a plumber once you notice these signs:

  • Nasty odors – if your catch a whiff of a sewer smell somewhere in your home, it will more than likely be related to an issue with your plumbing. At best, it can just be because of a p-trap or a drain that has dried out. But at worse, your sewer may be backing up or you have a broken drain pipe.

If the scent is strongest in the basement or somewhere outside of your home, it increases the possibility that the smell involves the sewer line.

  • Water is present on the floor, or there are wet spots on the concrete outside – cement is a porous material, even when it hardens and turns into slab. Because of this, water can seep through it. If there is any damage along your sewer line, water that leaks out of it will come up and form puddles over the slab.

While water on the floor or concrete can happen for various reasons, this happening without any clear and visible cause is likely due to a problem with your sewer line.

  • Various noises are present – you should only hear the sounds of running water when water flows along your pipes. But if you are sure that there is no faucet switched on or you hear gurgling noises whenever you flush the toilet, there may be a leak somewhere.
  • Water drains slowly – yes, slow drains are often due to clogged pipes, but if seems to be happening to all of your drains at the same time, sewer line issues may be the culprit.
  • Presence of mold and mildew – these fungi can appear in any home for reasons other than a sewer line problem, but don’t discount the possibility of it being sewer line-related
  • Visible cracks on the walls, floors, or foundations of your home – water can also affect the , no matter how sturdy they are. It can cause the soil underneath to move, which will affect your home’s structural integrity. Leaks coming from your sewer line can contribute a lot to this issue.
  • You experience – if the water does not completely go down the drain and seems to come back up, you likely have a clogged pipe. But even if this is the case, you need to get the sewer line checked as well.
  • Rats and other critters start running around your home – if you start seeing pests and you are sure that there is no way for them to get it, a break somewhere along your sewer line may have been their entry point.

The outside of your home is not spared from problems with a sewer line. There are also some other signs that you should keep an eye out for:

  • Some parts of your lawn are greener than others – the sewage that flows along the sewer lines carry fecal matter, which is a known fertilizer. If it leaks out, sewage will fertilize the soil, which improves the condition of the grass and nearby plants.

On the other hand, the bacteria present in the sewage can also destroy plants, so look for dead spots as well.

  • Visible sewage is present – water is not the only one that can pool on your lawn in case of a leak on the main lines. Sewage can as well, and when it does, it is going to be nasty.
  • Uneven lawn – if you spent a lot to make sure that you have a manicured lawn, indentations are the last thing you want. Unfortunately, this is possible when you have a leak on the sewer lines, as the sewage that leaks out displaces the soil and allows the upper layer to sink.

Whether inside or outside your home, a problem with your sewer line can make itself known to you. And once you see any of the signs, it is best to call a plumber before the issue gets out of hand.

Common Causes of Damage to Your Sewer Lines

Sewage pipes, in general, are sturdier than the indoor pipes we easily see. Because they have to be buried underneath the soil and concrete slab and carry along large amounts of wastewater, they have to be durable enough to hold all that weight.

But no matter how sturdy they are, sewage lines are still susceptible to damage. It is not just old age that can wreak havoc on the sewer lines, but also human action. Yes, despite the fact that they are buried underneath layers of soil and concrete, our actions can still have damaging effects to sewer lines.

How is this possible?


Despite its large openings, clogging can still occur along the sewer lines. Many people focus on the fact that the sewage pipes are larger than the indoor pipes, that is why they let food, grease, and other debris go down the drain. What they don’t realize is that these will not quickly go down the sewers, but will likely settle along the drain pipes.

Over time, this will cause a buildup that will prevent anything from passing through. When this happens, weak points will be created on the sewer lines. These weak points will be susceptible to breaks when pressure is applied to them, which will result in burst pipes.

This is how vital preventing solid waste from going down the drain is. If you only let drain-friendly substances enter the sewer lines, clogging will be non-existent. Unfortunately, some homeowners would still rather flush their trash down the toilet than throw them properly.

Activity on the Soil

It is unavoidable that the soil can get jostled, especially if work is being done on the ground that is in close proximity to the sewer lines. While this normally will not do any damage to the pipes, too much movement of the soil may cause cracks to form on them.

Worst-case scenario is that all that activity can cause the sewer line to completely break apart and collapse.

Also, digging around is not the only way for a sewer line to break without getting into contact with it. If the ground freezes during winter, including the sewer lines, this increases the chance of it suddenly bursting.

Rust and Corrosion

It is inevitable that sewer lines will get corroded over time, especially the metal ones, since they are constantly exposed to water. At the onset of corrosion, cracking will start to occur on the pipes. These cracks will get larger until the issue is remedied.

Tree Roots

For older sewer lines that make use of porous materials, such as clay, tree and plant roots can destroy them. Because these materials can allow water to seep through it, the roots will start penetrating the sewer lines to get to the water that flows inside.

Later on, their continuous growth and expansion on the pipe that they latched on will cause the sewer lines to break apart.

You may think that all these will only result in leaks, but since you are dealing with sewer lines, it will be a lot worse.

Any flooding that can possibly happen will involve sewage, so it is bound to be quite disgusting. Not only that, if the damaged sewer line seeps to your water line that also has break somewhere, the sewage can mix up with your water supply and end up flowing to your home, resulting in contamination.

Collapsed Drain Pipe Under Slab

No matter how properly installed and sealed a drain pipe is, there is always a chance for it to encounter problems, even when hidden underneath a concrete slab. A known issue is a collapsed drain pipe, which typically happens because of too much clogs present, as well as neglect and improper maintenance.

If your drain pipe collapses, this is something you will need to call the plumbers for. It will not just involve a simple repair that can be done by just anyone. In fact, many also consider it as an emergency situation that it will take some time for plumbers to repair.

There is a general consensus that this is the worst that can happen to any drainage system. You are not just going to deal with leaks, but also drainage issues, backflow of sewage that will go out via drains and toilets, overflow of wastewater, flooding, and strange behavior involving the fixtures of your plumbing.

Despite this, fixing a broken drain pipe that is found under a slab can be done by professionals. If you have a collapsed drain pipe, your plumber may just go for a spot repair. But if you have an old sewer line, it may be wisest to completely replace everything, especially if the plumber sees that other sections are starting to show signs of damage as well.

How to Replace Sewer Line Under Concrete Slab

If repair is to be done on pipes found underground, especially under a concrete slab, the traditional way of doing it involves digging and trenching. The plumber has to reach the sewer lines found underground, and the only way to do so is to cut through the slab to access them.

If the problematic sewer line is found outside your home, it will be easier to access. But if it is under your basement, it will involve destroying a section of your basement flooring and then having that flooring repaired after the work is done.

However, trenching is no longer the only method of replacing a sewer line. In fact, some plumbers can already fix a sewer line without having to dig. Not only can you avoid a ruined flooring and landscaping, but it can also help you save on repair costs.

Traditional Sewer Line Replacement

Whether just doing a spot repair or completely replacing your entire sewer line, the traditional method involves these steps:

  1. Identify where the problematic pipe is. Your plumber may look for wet spots on the concrete slab or flooring, but a better option is to use a camera specifically for sewers and inspect the entire sewer line.
  1. Once the broken drain pipe is found, your plumber will start removing the flooring over the damaged pipe, or over the entire path of the sewer line for a complete replacement.

An exception to this is if the basement flooring is made up of tiles. Since it can no longer be reused, plumbers use the jackhammer to make a hole without removing the tilework.

  1. Once the flooring is removed, your plumber will start making an access hole on top of the damaged pipe. This normally would involve a jackhammer, but a saw that can cut through concrete can also do the job. The best way to do so is by starting at the slab’s edges.
  1. After the slab is removed, your plumber will have to dig straight down through the earth or sand until the broken drain pipe is uncovered. Digging will continue if the rest of the sewer line needs replacing. Your plumber will also need to check for any utility lines found within close proximity to it.
  1. To have room to access the sewer lines and work on it, your plumber will need to create a trench on its sides. And if there are any roots near the pipe, they have to be cut or trimmed to prevent the roots from causing damage to the sewer lines in the future.
  1. The plumber will then cut away the damaged section of the sewer line on both ends. But if completely replacing everything, the entire sewer line will be removed piece by piece.
  1. This cut section will be replaced with PVC or the same pipe material as the old one, although PVC is often used. To connect the new pipe to the existing sewer line, rubber repair couplings that come with compression bands made of stainless steel will be used.

Your plumber will follow the process of installing new pipes if the old ones have been completely removed.

  1. Once the new drain pipes have been installed, the sand or soil will be put back and concrete will be poured over the hole to cover it up.

Before doing the sewer line replacement, you should remove furniture and other items in the basement if the work is going to be indoors, as it will be messy. If removal is not possible, get something to cover them up, such as plastic sheets or tarpaulin, to lessen the cleanup needed afterwards.

Sewer Line Replacement Without Digging

Trenchless sewer line replacements have become possible with the use of different equipment. Instead of digging, plumbers will access the sewer lines via manholes. But if the manhole is too far, small access points will be made along the sewer lines.

For this option, there are two types available: cured-in-place pipe lining, or CIPP, or pipe bursting. Here are the steps on how to do the sewer line replacement for these two methods:

Cured-in-Place Pipe Lining

  1. The sewer camera, which will be inserted through a manhole or access point, will be used to get a visual of the sewer line and identify what method needs to be used for cleanup.
  1. The entire sewer line will then be cleaned up, either via flushing, using a sewer-cleaning cable equipment, hydro jetting, or other means.
  1. The new flexible pipe material, which is usually fiberglass or polyester and should be as long as the length of the drain pipe from one manhole or opening to the other, is then inserted to the existing drain pipe either via a cable or pushed into place by water or compressed air.
  1. This will then be inflated and will undergo curing to harden, with the use of UV, hot air, hot water, steam, or ambient air that is pressurized, depending on the material.

Pipe Bursting

  1. Like the CIPP method, pipe bursting will start from one manhole or pit and end in another opening. The machine to burst the pipe, which is already connected to the replacement pipe on its other end, is inserted to the manhole and placed inside the damaged sewer line.
  1. A cable, often a steel-type, is then inserted into the other manhole and pushed inside the pipe until it connects with the machine’s burst head.
  1. This cable will pull the machine towards the cable’s entry point, with the burst head destroying the old pipe and laying out the new one in the same path as it moves.
  1. When the burst head reaches the other manhole, it means that the new pipe is now set in place. The plumber will then disconnect it from the new pipe, and the new pipe will then be connected to the existing sewer line.

Whichever method you use, check if permits are needed. Some states require it, since it will be dealing with sewage and possible work on manholes. Some states are very strict when it comes to this type of job, even requiring inspections as the work progresses.

Preventing Damage to Sewer Lines

While it is natural for sewer lines to age and eventually fail, you can easily maximize their lifespan, no matter what material you use. Sewer lines are known to last decades, reaching a century, as long as they are properly maintained. It’s the same way that different states have different contractor licensing requirementsIdaho’s rules will differ from Texas’ and Washington State’s.

When it comes to sewer lines, proper maintenance entails the following:

  • Only letting drain-friendly materials and substances enter the sewer lines. This means no grease, paper towels, diapers, paint, hygiene products, thick liquids, leftovers, and other similar objects.
  • Having your sewer lines regularly inspected by a camera. It is better to spend a little over a hundred dollars for an inspection every now and then to catch issues early on, than wait until the sewer lines are in terrible shape until you do so. Catching problems early will save you from a lot of headache and high repair costs.
  • Identifying the path of your sewer lines and not placing heavy objects over them. Despite having concrete slabs, too much weight placed on them can still affect the sewer lines found underneath. At worse, it can potentially result in a collapsed drain pipe.
  • Installing barriers to prevent roots from attaching themselves to the pipes. This should ideally be done prior to the installation of your pipes, but they can also be done when the pipes are already in place.
  • Never pouring volatile chemicals, especially strong acids, down the drain. While sewer lines are composed of durable materials, they are not completely immune to the effects of harsh compounds. Constant exposure to them will still cause corrosion.
  • Prevent installing them near existing trees and plants. If the sewer lines are yet to be placed, have them installed away from plants, especially trees. Roots will spread out as they grow, and they may attach themselves to nearby pipes and cause damage.

If you think doing regular maintenance is going to cost you a lot, wait until you see how much you would have to spend on a sewer line replacement, especially in severe cases. This would make you change your mind about throwing leftovers down the sink the next time.

Cost to Replace Sewer Line Under Concrete Slab

Sewer line replacements are not a simple task, as it requires skill, experience, proper knowledge, and not to mention, expensive equipment. It will also take some time to fix, and you may also have to figure out temporary living arrangements elsewhere as work commences, as this task will involve your entire plumbing system as well.

Sewer line work means no using the showers, sinks, and even the toilets until your sewer lines have been repaired or replaced.

From all these, you probably know where we are getting at – the repair of any under slab plumbing is bound to be quite pricey.

To be precise, the cost to replace your sewer line under the slab ranges from a little over $1000 to $4000 for minor or spot repairs, while a full sewer line replacement can go for as much as $3000 to as high as $25,000.

The actual cost will depend on the chosen method of replacement:

  • Traditional Trenching – $4 to $12 per foot for the trenching, and $50 to $250 per foot for the digging and pipe replacement.

Note that some plumbers may suggest hiring other contractors for the excavation part, especially if it is going to difficult for them.

  • CIPP – $80 to $250 for every foot
  • Pipe Bursting – $60 to $200 per foot

It will be always be a case-to-case basis in terms of determining which method is going to be cheaper for you. Other factors will also affect the total repair cost of under slab plumbing, such as:

  • The lot area, as a bigger land may mean more work for the plumber
  • Presence of trees and plants near the sewer line
  • Location of sewer lines, e.g. if they are found under the basement, driveways, concrete decks or patios, etc.
  • Size of your home
  • Difficulty of excavation due to the type of soil present

Have your plumber assess what method is going to be more practical for you.

Getting Quotes from Competing Contractors

We all want to save on repair costs, especially with expensive projects such as a sewer line replacement. This is also the main reason why many homeowners would rather fix home issues themselves with the help of YouTube and online tutorials. But, the results are always a mixed bag.

Unfortunately, this is one of those projects where homeowners are at the complete mercy of contractors. Plumbers know this is not a job any homeowner can do, and many of them take advantage of this fact and have exorbitant rates for a sewer line repair or replacement.

But, it does not mean you should just accept the quote of the first plumber you ask, especially if you feel that it is overpriced. You should always compare the quotes of plumbers when you can, and let them know that you are also in touch with other willing plumbers.

This simple strategy will likely result in you getting lowered quotes or better offers, as well as the chance to bargain, because knowing about the competition will ignite their competitive streak. They will fight over you and attract you to be their client by hitting your weak point, which is their quote for the job.

After all, who doesn’t want huge discounts?

And if you are wondering how you can do this without spending hours going around your neighborhood and looking for plumbers to inquire and ask quotes from, you are in luck. Our online service will let you do all that and more without having to leave your home. You just have to:

  1. Fill out our form, and
  2. Wait until up to four send you their quotes for the job.

It really is that simple. Best of all, we offer this service to you for free!

If you are wary of using it because you think you are obligated to hire one of those contractors who send their quotes, don’t worry. You are free to turn them down if you are not interested in any of their offers.

Remember, time is of the essence when it comes to sewer line replacements. So, use our service now to find a qualified plumber asap to work with you and get it fixed!

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