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Top-Rated Plumbing installers for a remodel or addition in O Fallon - Updated Nov 2026

Avatar for Ambassador Plumbing L.L.C
Ambassador Plumbing L.L.C
5.0(
40
)
Plumbing for a Remodel or Addition - Install

Serving O Fallon, MO and surrounding areas

Approved

In business since 2019

Free estimates

Emergency services offered

"Awesome. Showed up on time. Courteous. Clean. Of the several company reps that I spoke with Austine Ambassador Plumbing) gave me the most confidence. I will definitely work with them again!"
Response time1 day
Response rate100%
1 neighbors recently requested a quote
Avatar for MH Contracting, LLC
MH Contracting, LLC
4.8(
70
)
Plumbing for a Remodel or Addition - Install

Serving O Fallon, MO and surrounding areas

Approved

In business since 2012

Free estimates

Warranties offered

"Mike and his team are absolutely wonderful to work with. We moved into our new home in October of 2020 and our basement was completely unfinished at the time. We worked with Mike to create plans to add a bedroom, office, laundry room, family room, and an additional bathroom. During the project, we were so happy with Mike and his team that we asked if he would be able to help us with the upstairs as well. For the upstairs, MH contracting removed a wall that separated the kitchen and living room, removed carpet in the bedrooms, updated two bathrooms with new tile and vanities, along with installing new vinyl plank flooring throughout the upstairs. The wall was removed flawlessly and you would never know that there was a wall there. For the basement, they stabilized the stairs, installed completely new framing, fixed plumbing components that were not up to code from the previous owner, fully insulated and dry walled, painted, all new electrical and panel upgrades, added an egress window, and laid new vinyl plank flooring. The basement is now completely finished with proper permits and fully passed inspections. Mikeâ s communication was great throughout the entire project and all of his team members were very polite, clean, and helpful. He kept us up to date on any material delays throughout the pandemic and set proper expectations. There were material delays that were out of Mikeâ s control so the projects took about four and a half months to complete but they were a pleasure to work with the entire time. We would absolutely recommend Mike and his team to any of our friends and family for any work youâ re looking to have done to your home or business."
siding job
siding job
siding job
Siding job
Bathroom remodel

+196

Response time1 day
4 neighbors recently requested a quote
Recommended by96%of homeowners
Avatar for Mr. Rooter Plumbing of St. Charles
Mr. Rooter Plumbing of St. Charles
4.2(
340
)
Plumbing for a Remodel or Addition - Install

Serving O Fallon, MO and surrounding areas

Approved

In business since 2017

Free estimates

Emergency services offered

"Garrett Korn was my installer from Mr. Rooter. I was informed prior to his arrival that he was on his way and he arrived shortly after 8:00 for an 8 - 10 AM window. He quickly analyzed our plumbing problem, gave us a quote right away (which I agreed to) and then left to get all the parts he needed. He was only gone for a short period of time, did all the work, and was totally completed before 10:00 AM. The quality of the work was very good and now we are up and running again. I would highly recommend Mr. Rooter and selfishly ask for Garrett. He is easy to work with and very competent."
Mr. Rooter of St. Louis
Mr. Rooter of St. Louis
Mr. Rooter of St. Louis
Mr. Rooter of St. Louis
Mr. Rooter of St. Louis

+7

Response time6 hrs
44 neighbors recently requested a quote
Recommended by89%of homeowners
Avatar for MetaMorph LLC
MetaMorph LLC
5.0(
6
)
Plumbing for a Remodel or Addition - Install

Serving O Fallon, MO and surrounding areas

Approved

In business since 2015

Free estimates

We take great pride in our experience, expertise, quality, and customer service that we provide to meet the consumer’s needs. It is our mission to provide excellent workmanship and complete customer satisfaction from start to completion of a project. In order to understand the needs and expectations of our customers, we take great care to work and communicate with every customer in a professional manner. Our reputation is based on service, safety, and quality, regardless of how large or small the job.

After
Before
1 neighbors recently requested a quote
Avatar for Bieg Plumbing & Mechanical
Bieg Plumbing & Mechanical
4.6(
120
)
Plumbing for a Remodel or Addition - Install

Serving O Fallon, MO and surrounding areas

In business since 1960

Free estimates

Emergency services offered

"It was amazing work performed! Professional, prompt, thorough, polite, timely, etc. I cannot come up with enough adjectives to describe the quality of work they did! Dennis, Dave, tile guy (can't remember his name) were awesome in all they did and we thank you for that! And to mention the front office folks - Stephanie was so polite and accommodating every time I spoke to her. Bieg Plumbing is who I recommend!! Thanks, Tom Roth- 3815 Holly Hills"
Additional Photos
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Commercial Rooftop Unit Replacement

+5

Recommended by90%of homeowners
Avatar for Mayo Plumbing Co
Mayo Plumbing Co
4.8(
481
)
Plumbing for a Remodel or Addition - Install

Serving O Fallon, MO and surrounding areas

In business since 1990

Free estimates

Emergency services offered

"John has been our go-to guy for several years now. We live in an early 70s home, and as with all older homes there are repairs that are needed fairly often. From the first time he worked for us, identifying that a leak originated from a roof vent that had been knocked slightly askew in a storm and rain water had gradually seeped down the pipes and terminated above our kitchen cabinets, he has always been prompt, courteous, professional in every way, and just an all around nice guy to work with. And the pricing has always been fair. Since then he has installed a number of appliances and fixed sundry leaks for us. Can't recommend him or his company enough. Give them a try."
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+3

Recommended by96%of homeowners
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FAQs for plumbing installation for a remodel or addition projects in O Fallon, MO

Adding bathroom plumbing to a detached garage starts with the basic line installation cost of $900 to $1,300. On top of this base expense, you'll need to budget for each fixture. A toilet costs  $250 to $550, sinks cost $150 to $800, and a shower or bathtub costs $400 to $1,900. The project will also require ventilation, moisture-resistant materials, and possibly electrical work. Remember that these costs reflect only the plumbing aspects—additional construction, finishing, and permitting expenses will apply to complete a functional bathroom space.

While certain aspects of garage renovation might be suitable for DIY enthusiasts, plumbing installation requires professional expertise. Connecting to water and sewer systems demands specialized knowledge and equipment, and improper installation can result in severe water damage, code violations, and potential health hazards. Most municipalities require permits for plumbing modifications, and these often stipulate that licensed professionals must perform work. Consider limiting your involvement to simpler tasks like painting or basic finishing work.

The timeframe for adding plumbing to a detached garage spans one to three days for the actual plumbing work. However, this represents only the active installation period. The complete project timeline must account for planning, obtaining permits (which can take weeks depending on your locality), coordinating multiple contractors if needed, and addressing any unexpected challenges that arise during installation. Weather conditions can also impact excavation and outdoor connection work.

Adding plumbing to a detached garage will likely increase your property taxes. Tax assessors consider plumbing an improvement that enhances property value and functionality. The specific tax impact varies by location and project scope. Converting a garage into living space with plumbing facilities can trigger significant reassessment in many jurisdictions. Before proceeding with your project, consult your local tax assessor's office to understand the potential tax implications and factor this ongoing expense into your decision-making process.

The O Fallon, MO homeowners’ guide to plumbing installations for a remodel or addition

From average costs to expert advice, get all the answers you need to get your job done.