Mainline Plumbing

Mainline Plumbing is a family-owned plumbing and water-treatment company based in Londonderry, New Hampshire, serving the surrounding area. The company's website places its founding at two different years — 1992 on one part of the site and 1987 on another — while the Better Business Bureau lists a 1994 start date; whichever figure is accurate, the business has operated in southern New Hampshire for decades. John, whom customers repeatedly describe as the owner, is closely involved in day-to-day jobs alongside a small crew that includes technicians named George, Connor, Rick, Ben, Braddon, Alex, and Mike. Customers most consistently praise the company's well-system and water-treatment work: replacing well pumps and pressure tanks, and installing PFAS, radon, arsenic, and bacteria filtration systems along with water softeners. Several reviewers describe John walking them through PFAS test results and the state rebate process, with a full treatment system installed and running within a couple of hours of approval. The company also handles general plumbing and heating work — furnace and boiler repairs, drain replacement, and water heater installation — and responds to emergencies quickly: reviewers describe crews arriving within an hour or less for a dead well pump, a flooding heating system, and a lost water supply, including on nights and weekends. Many reviewers say they have used Mainline for years or across multiple properties, calling out George, Connor, and Mike by name in addition to John. Reviews from the past six months include no negative reports, and the broader history — nearly 600 reviews dating back to 2021 — is overwhelmingly five-star with very few complaints of any kind. Mainline holds an active New Hampshire Master Plumber license (#3072), verified directly against the state registry under the name Richard A. Matckie, II, and the company's own site cites the same number. The Better Business Bureau, however, lists two different license numbers for the business on its profile, which grades the company A+ as an accredited member. Before booking, it's worth confirming pricing directly, since reviewers describe being given several options at different price points rather than a single quoted rate. If you're relying on a BBB listing rather than the company directly, it's also worth asking which license number applies to your job, since BBB's numbers don't match the one verified with the state. Overall, this is a well-established local outfit best known for well pumps, water treatment, and fast emergency response, with many repeat customers and a verified plumbing license.