Brian Patrick Cassidy, of Lincoln, passed away on July 28, 2021 at Massachusetts General Hospital. Mr. Cassidy was born in Cambridge on February 8, 1951 a son of the late Verna Elizabeth (Cavicchi) and the late Harry James Cassidy. Brian grew up in Lincoln, attended school at Lawrence Academy and Xavier High School, and graduated from UMASS Lowell with a degree in Electrical Engineering. He was owner and business manager of the Cassidy Water Conditioning Franchise of Culligan USA, which he helped found in 1968 along with his father in Lowell, Mass. Brian was extremely dedicated to the business and felt his team at work was his extended family. He was a communicant of Holy Family Parish in Concord, MA. Brian was fun-loving, and he most cherished time spent with his family and friends, particularly at barbecues or enjoying a good meal together. He was a fan of the Bruins and liked watching and attending hockey games. He also loved to travel, particularly to Italy where his mother's family was from. He is survived by brother Terrence Cassidy and wife Patricia; niece Lauren and husband Jeremy Luallen and their son Ethan; and nephew Eric Cassidy and wife Jennifer, and their children Haleigh, Liam, Logan, Lucas, Ava and Keira. Family and friends will gather for visiting hours on Wednesday, August 4th from 8:45 to 10:45 am in the Dee Funeral Home, 27 Bedford Street, Concord Center. His Funeral Mass will be celebrated at 11 am in Holy Family Parish, Monument Square, Concord Center. Please click here to view the church livestream of the Mass . Burial will follow at St. Bernard's Cemetery in Concord. In lieu of flowers, the family requests that donations be made to Charity Water via www.CharityWater.org Arrangements are under the care of Dee Funeral Home & Cremation Service of Concord.