About Us

The highly professional team employed by B. F. Mahn & Sons, Inc. will do only top quality work to meet your residential or commercial plumbing and HVAC needs. From new construction to minor daily repairs, B. F. Mahn & Sons, Inc. will make it right. It is a business built on a strong foundation, impeccable reputation and first quality service skills.  The family owned and operated business has been resilient through the ups and downs in the economy over the last 140 plus years. It has survived the Depression and more recent economical challenges. 

Bernard F. "Biff" Mahn III and his sister Beth (Mahn) Ross of DeSoto, take pride in running the family business out of the same two-story brick building where their great-great-grandfather was recorded as a blacksmith in 1868. The sibling team manages B. F. Mahn & Sons, Inc. - Plumbing, Heating, Ventilation and Air Conditioning - 112 W. Clement Street, which the family believes to be the oldest business (family or otherwise) still operating in DeSoto...

It began as a horse and carriage blacksmith shop with no formal name operated by John Kempe. Kempe's blacksmithing business continued into the second generation with his son, Henry Kempe. Henry's daughter, Mildred, married Bernard F. "Dutch" Mahn, who expanded his in-laws' operation in the 1920s. Dutch started a tinsmithing shop on the upper floor, where he did gutters, roofs and stovepipes. For a little over a decade, both business thrived, blacksmith on street level and tinsmith on upper level. By the mid 1930's, even the largely rural, horse-and-buggy town of DeSoto, was going mobile as automotives became the transportation of choice, and the need for blacksmithing services faded. The family restructured the business plan to advance with the changing times.

As an innovative entrepreneur, Dutch Mahn led the area in a new direction with the advancement of indoor plumbing and heating technologies. Phillip “Phil” William Mahn and Bernard F. “Bernie” Mahn, Jr. were next in line to continue the legacy in the 1950’s. Bernie ran and expanded the thriving business while Phil continued with the plumbing and tinsmith skills.

Biff Mahn’s own introduction into the business came at a tender age of 10. He began holding flashlights for the men and sometimes getting into crawl spaces, in between floor joists or anywhere else the bigger guys couldn’t fit. He didn’t collect a dime but gained priceless knowledge. He began earning a paycheck during high school, working summers as a plumber’s apprentice. He’s been there ever since.

Beth (Mahn) Ross started working summers when she was 15, but unlike her brother, she didn’t come back into the family business as an equal collaborator until 1993 when Bernie was forced into early retirement due to failing health. Beth stepped into her father’s shoes, running the business and continues as a respected leader in the community.

The next generation has been launched at B. F. Mahn & Sons, Inc. Jonathan “J.P.” Mahn has put on the uniform in the image of the exceptional men before him. J.P. attended the local college to gain his certification. His education, his determination and his natural ability will take us into the future…

B. F. Mahn & Sons, Inc. is here today - and will be tomorrow.


We are certified licensed plumbing and mechanical contractors and are associated with the Better Business Bureau and NFIB. We are bonded and insured. Feel good about trusting us!

We service and repair plumbing, heating, air conditioning, heat pumps, whole house generators, geo thermal systems, and water heaters, gas lines, radiant floor heat, water conditioners.  We have years of experience standing behind us as well as keeping current with continuing education courses. We stay "state of the art".

We feature major brands like Delta, Moen, Heil, and Trane. . .A.O. Smith, Bradford White, Quiteside, Kohler, Toto, Mansfield, Zoeller, Elkay, Simmons, Aquaglass, Lasco, Basco, Gerber, Noritz, North Star, Swanstone, American Standard, Rinnai, Watts, Wirsbo, Zurn, InSinkErator, Grohe, Chicago, Sterling, including the servicing of all makes and models such as Amana, American Standard, Carrier, Comfortmaker, Goodman, Lennox, York, etc. If it's available, we can find it. If it can be fixed, we can fix it!

We have always done and continue to do full new construction plumbing and HVAC. Need another bathroom, need to take out a bathtub and replace with a safer step shower or walk in tub? We are experts in the field and can help you make the most of your space without breaking the bank! Give us a call, just ask for an estimate. We are happy to help.

We offer on call service Monday through Friday between the hours of 8 AM to 4:30 PM. Our office is open until 6:00 PM.  We accept most forms of payment including Discover, Visa, Mastercard, Cash, Check, as well as invoicing. 

We service the surrounding communities: DeSoto, Festus, Hillsboro, Crystal City, Cadet, Grubville, Dittmer, Richwoods, Arnold, Barnhart, Fenton, Herculaneum, High Ridge, House Springs, Imperial, Lonedell, St. Clair, Hematite, Mapaville and more.

Thank you for your continued support! We appreciate your business and will always treat you like family!  God bless!!





Click any photo below to get a larger view or view the slideshow.


Reviews Review this provider

There are no reviews for B.F. Mahn and Sons Inc.. Be the first to review this provider.
Want a fast response from B.F. Mahn and Sons Inc.? Noodle them!

You have selected 1 service provider(s).

ServiceNoodle Verified

We verify all service providers on the Service Noodle network to bring you the best quality services around.

Phone Phone Verified