Sewer & Drain Services: OneVac provides a full spectrum of professional sewer and drain, plumbing and excavation services. Based in lower Fairfield county, serving Stamford, Greenwich, Darien, New Canaan, Norwalk, Wilton, Westport and Fairlfield Connecticut. Emergency services 24 Hours a Day, 7 Days a week.floor drains, curtain drains, shower drains and roof drains. Sump pump repair and installation, wa...