We are A.G. O’Brien

A.G. O’Brien Plumbing Company was founded in 1934 by Irish Immigrant Adam George O’Brien, more commonly known simply as A.G.

A.G. O’Brien built this company, which focused primarily on residential plumbing, heating, and sheet metal work. A.G.’s vision was to deliver a top-notch customer experience and to place a strong emphasis on providing a quality product with unmatched craftsmanship.

In 1971, the A.G. O’Brien Company was taken over by Derrill Adatte Sr.. Under Derrill, the company expanded its residential division and developed a commercial plumbing, heating, and ventilation division. Derrill Sr. ran the company until 1982 before passing it on to his son,  Derrill John.   In 1999, Derrill John added a fire sprinkler division and relocated the ever-expanding business to the Hermantown Industrial Park, where the offices and fabrication shops remain to this day.  The company is currently going through another family generational handoff to Chris Adatte.


After nearly 90 years in business, A.G. O’Brien Plumbing and Heating Company has never lost sight of its core values. Customer satisfaction is our purpose, and quality craftsmanship is our credo.

Let our family take care of yours!