How To Install A Plumbing System In Existing Concrete Slab?

Concrete slabs have been used to construct many houses. This is a cost-effective construction method, but it may lead to severe plumbing issues with the aging of the house.

The pipes are placed before the concrete is poured as well as completely enclosed after pouring the concrete.

This is done at the time of installing the plumbing system during construction. The pipes are sometimes placed in the dirt under the slab. Unfortunately, if a pipe cracks, breaks, or bursts, then this can be a major headache for you.

Do you need a step-by-step tutorial on how to install plumbing in existing concrete slabs that is fast, simple, as well as precise? So, here’s the deal: I’m going to be completely honest with you. It’s going to be difficult. To begin with, there will be sawing, excavating, and a lot of dust.

Using the services of a professional plumber seems to be a viable option. However, if you want to attempt it on your own, below are given step-by-step instructions that will guide you through the overall process.

Step-By-Step Instructions

Ø  1st Step – Consider Taking Your Measurements And Buy Your Pipe

To take the measurements, you’ll need designs of your structure. Pay careful attention to the printed measurements as well as sketch out the position of each pipe under the concrete slab using a measuring tape.

Spray paint or chalk can be used to draw the lines. This is the time to figure out how much pipe you’ll need. You should focus on purchasing pipes of the same material and grade as the current pipes.

Pro Tip: Being precise at this stage can save you a lot of money in the long run. Make sure you know where all of the existing pipes are located.

Ø  2nd Step – Making A Cut Mark

You should remember that drain lines should be in the simplest possible arrangement, with a few twists and turns as possible.

It is very important to determine the new line’s center as well as endpoints at its starting or origin point. Spray paints for marking the center as X, then draw two lines on each side to form a complete mark.

Important Tip: Pipes should never be installed horizontally specifically through a concrete slab. It should go vertically through the slab support to enable effective subsequent connections.

Ø  3rd Step – Cutting The Concrete

It’s now time to get down to business with some mechanical work. On the wet concrete saw, place the diamond blade on the X position which is the drain line’s center.

Cut approximately 4 1/2 inches deep as well as continue cutting between the place of origin and the terminus following both indicated lines.

This procedure can be very loud and time-consuming. You may need to take a break. Prepare to invest more time as well as effort if the concrete slabs include a lot of steel reinforcement.

After cutting both lines, shatter the concrete strip into pieces with the help of a sledgehammer as well as a demolition hammer (if necessary). Remove any leftover concrete, and you may need to build a drain trench in the soil or sand. A mechanized digger can be useful in this aspect.

Pro Tip: Protect yourself against unforeseen accidents by using proper safety equipment, good back support, as well as protective glasses. Also, before putting in the new pipes, get rid of the concrete waste.

Ø  4th Step – Putting The Pipes In Place

In the drain trench, place the pipe. Ascertain that the pipe is supported by sufficient pipe support as indicated in the architectural design.

Make vertical connections where pipe must travel specifically through the slab. The tubes should reach at least 6 inches above the concrete slab’s top. If a twist or turn is unavoidable, use a high-quality pipe junction that is available in the proper form.

Pro Tip: Taking the time to mark as well as measure ahead of time can save you money on last-minute purchases.

Ø  5th Step – Covering The Pipe Mouths

Cover the pipe mouths with tape after fastening the pipes in place. This helps to keep the debris out of the pipe.

Otherwise, even before you pour concrete over it, concealed material may create a clog in the pipe. If that occurs, you’ll have to break the pipes to figure out where the obstruction is, which is something we don’t want to happen.

Ø  6th Step – Filling The Trench With Concrete And Soil

Now, you should focus on covering the pipelines with the help of soil. Fill the trench with a hand shovel until the backfill is even with the floor. You’ll have to level the whole floor if the drain is higher than the current floor. That will require a lot more time as well as work.

Pour the concrete over the soil and set it aside for the specified amount of time. You’ve completed the task!

  Frequently Asked Questions (FAQs)

      How Do You Install A Drain In A Concrete Floor That Already Exists?

The installation of a floor drain into an existing concrete floor will require some concrete cutting and excavating. As the job requires heavy equipment and a lot of dust, you can contact expert sewer and drain services. They will perform it for you.

Cut the concrete with the help of a wet saw concrete for those who wish to do it themselves. Dig the trench as well as install the new pipes in it, following the markings. Before pouring it into the concrete, level it with soil.

      Is It Possible To Relocate Plumbing On A Concrete Slab?

Yes, you certainly can. However, it is a time-consuming as well as a messy operation that requires much more technical accuracy than replacing plumbing in a concrete slab. Professional kitchen remodeling services for a 200-square-foot kitchen may cost anything from $2,000 – $7,000.

To prevent damaging the pipe, careful sawing as well as excavating the concrete slab is required when you are doing it yourself. Make another cut for the completely new drain line once you’ve removed the pipes. Install the pipes and make sure that the floor is leveled up.

      How Difficult Is It To Add A Bathroom To A House Specifically On A Slab?

To be honest, it’s not easy, but it’s not impossible. If required, make a note of them. Now map out a plan for the new pipes you’ll need to put in.

To install the plumbing supply as well as drain lines, cut and remove the concrete slabs to remove the part of the slab required. Pour fresh concrete over the pipes and level the floor after they’re in place.

      What Is The Depth Of Plumbing Pipes Under A Slab House?

Under a slab house, the plumbing pipes are specifically about 18 inches to 3 feet deep. In general, they are buried below the frost level, but when they rise above the frost line, they are adequately insulated to avoid damage.

The pipes are approximately four feet below ground level on the exterior. In the winter, raising them over 4 feet can cause them to freeze and explode.

      Is It Possible To Run Water Pipes Through A Concrete Floor?

Yes, water pipes can be routed through a concrete floor. They can also make their way under stoops, sidewalks, decks as well as patios.

However, keep in mind that the pipes usually run in the soil under the pavement, not in the main concrete. Trenches are dug before pipes are carried through concrete at places where they must pass through concrete. Concrete is then used to cover and level it.


After reading this article, I hope you have got a very clear idea about the best ways to install a plumbing system in your existing concrete slab.

If you are not confident, then it would be best, if you seek the assistance of a top emergency plumber who will help you in this aspect. Not only that, but they will also help you to get the best outcomes.

Author Bio:- Aimee Grace

Aimee is a marketing manager at EZ Plumbing & Restoration. She is very passionate in writing about discrete plumbing services and leakage detection as well as repair solutions.  Her vision is to educate people about the consequences of water and slab leaks at home or office and what they should do to repair them to avoid further water damage as well as property damage. 

 Innovations have paved a way for smart devices to lead a convenient life. Plumbing industry is no different but only few people know about various tools used to fix the leakages. Stay tuned with the recent articles to know all about how to find water damage, slab leak, clogging, and ways to repair them, installation of new HVAC appliances in San Diego.