Basement Bathroom Plumbing | Learn to Plumb a Basement Bathroom


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A basement bathroom plumbing requires a combination of skill, care, and experience. This is one of the most difficult household chores, so it is recommended that you hire a professional to accomplish it. A plumbing system for an above-ground bathroom is much easier to install, usually during the day, so decide on your priorities and assess whether or not a basement toilet is needed.

Basement Bathroom Plumbing

Basement Bathroom Plumbing

It may be necessary to remove some of the concrete to install the plumbing in the basement bathroom and may not be easy to get the necessary accessories to install plumbing fixtures in a bathroom in the basement – tub, showers, etc. It takes extra effort to keep kids safe. 

Basement concrete floor usually requires fracture. Marks are set on the surface along with a given range, and the concrete is chipped, usually using a jackhammer. The debris should be cleaned up, and the new water lines should be properly bonded to the old ones. 

The new facility should be filled with concrete once it is finished. 

In some homes, the downspout is located below ground level. The plumber can help you by providing various estimates of the location of the drainage lines and plans for installing the plumbing. It’s also possible that the main drain is located below ground level in some homes. 

You can make a raised bathroom floor to help in these situations. In this case, the ceiling must be high enough. The fixtures will be situated above the sewer line if you build a raised floor. This eliminates the requirement for a sewage ejector system to be installed. Bathroom plumbing in the basement is a unique sort of plumbing. 

As a result, extra caution should be exercised when building, maintaining, repairing, or replacing plumbing in a basement bathroom. If you plan to install plumbing fixtures in your home, you can hire a qualified plumber to help you.

How to Add a Bathroom to the Basement

Basement Bathroom Plumbing

The basement plumbing provides more than a sink and an additional toilet. It also adds convenience to your home life. It is a great first step in freeing up unused space on the basement floor and turning it into a comfortable, livable space maybe even a separate apartment for rent. 

Learn More: How To Build A Basement Under An Existing House

However, keep in mind that there are special considerations when it comes to installing plumbing below grade. The depth of the existing plumbing is critical – if there is room for the sink and toilet above the current flush depth, the job will be much easier.

However, if the sewer line is not deep enough, you may need to install a pump or other method to remove the sewage from your home. Your local building code may also have specific rules regarding underground plumbing installations.

There are several factors to consider if you decide to continue building your basement bathroom. The construction of your basement limits you to some extent. But if you can place the bathroom next to the existing plumbing, you will make your life easier when it comes to plumbing. Using existing space costs 40% to 60% less on average than adding space.

You still have to know if you want to add a sink with a sink and toilet or if you need to equip a bathroom with a bathtub or a shower. The walk-in closet is much simpler and cheaper, but a bath or shower is essential if you want to use the basement as a guest bedroom or apartment. Also, since basements are generally more humid than the air in the house, you should install a ventilation system to prevent mold and mildew from forming.

How to Install a Bathroom in the Basement

  • Unfold the lower 2×4 wall panels to form the bathroom’s perimeter walls.
  • To find the center of the shower drain and toilet flange, measure the wall plates.
  • Dig a trench that extends from the existing downspout to the new shower drain lines and toilet flange.
  • Use an angle grinder with a diamond grinding wheel to cut the old cast iron drain pipe.
  • Attach a flexible mechanical coupling without a hub to the end of the drain tube you just cut. Tighten the clamp on the cast iron pipe using a torque wrench.
  • Cut and glue 3″ PVC pipe and fittings to form a downspout assembly that connects the cast iron pipe to the new shower and new sink. This will be a vertical cast iron pipe, more than likely 4″ in diameter.
  • Insert the end of the PVC waste pipes into the mechanical sleeve attached to the old cast iron pipe. Tighten the PVC hose clamp.
  • Then connect a 2″ PVC pipe from the downpipe to the showers cubicle and sink.
  • Install traps for each fitting and make sure the pipe slope is ⅛” per foot for proper drainage.
  • Insert a ½” steel rebar into the ground next to each trap. Then use duct tape to secure the rods to the traps. Check the rough piping before emptying the concrete floor. Know the “rough-in” of your basement toilet (the distance from the wall to the center of the drain, most likely 12 in).
  • Close the open end of the toilet tube with the foam cap. Wrap plastic wrap around the drain tube.
  • Have the concrete contractor fill in the new floor around the pipes.

Frequently Asked Questions

How much does the rough bathroom cabinet cost in the basement?

For a registered, licensed plumber who knows their trade, this project takes 8 hours a day and costs between $ 320 and $ 600, based on salaries ranging from $ 40 to $ 75 an hour for 8 hours.

Is it possible to put a full bathroom in the basement?

If you add a bathroom to a finished basement, it won’t look like a basement anymore; instead, you will feel like a comfortable space where you and your family can relax and have fun. Putting a bathroom in your basement turns it into a living space, increasing your home’s overall market value. Expect your bathroom to run about 30%-50% of your total basement finishing costs.

Does adding a bathroom in the basement add value to the home?

Adding a bathroom to your home increases the value by 10% to 25%. It depends on the size of the bath, the finishing you choose, and where you live. Half bath adds about 10% to your home’s value, while a full bath adds 15% to 25% to your home’s value.

Is it difficult to put a bathroom in the basement?

Redecorating an existing bathroom can be done quite quickly. A more thorough renovation typically takes four and a half to nine weeks. If you expand your home to add a bathroom, you can expect the job to take a little longer

What is the cost of installing a bathroom in the basement?

On average to add a bathroom to a basement cost between $8,000 and $15,000. 

If you already have an overflow pipe common in new homes and near the main drain – Since 2000, the percentage of new single-family homes with 3 or 4 bathrooms is between $500 and $1,000.

How to put a bathroom in a basement without breaking the concrete?

The best way to install a shower in the basement toilet without damaging the floor is to watch the toilet flush upwards. Unlike standard basement showers, the Saniflo system is put on concrete floors, which require piercing the showerhead and concrete to build a drain.

How much does it cost to install plumbing in a new bathroom?

The cost of installing plumbing in a bathroom ranges from $ 1,500 to $ 4,000, depending primarily on the number of accessories needed. You’ll usually recover 60% to 70% of your bath install investment when you sell.


The basement bathrooms are expensive and luxurious. Planning is everything for this project; otherwise, you may end up with an expensive unfinished project. If it is possible to carry out this project independently, it is best to leave it to the professionals.

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