TLDR version: Mainline Plumbing is awesome. They replaced our tankless water heater pretty much immediately, did an excellent job at a good price (OK, a good price for a tankless water heater since tankless water heaters aren't cheap), and cleaned up after themselves like they had never been there! For comparison, this job cost us a couple of thousands of dollars less than a coworker paid for basically the same job just a few months ago. That coworker lives in Massachusetts, so that might make a difference, but I am very happy with the price. For those that like details: after 16 years of use, our tankless water finally needed a new flame rod and igniter. As I was looking to see if cleaning them would help (it did), I noticed the heat exchanger was leaking. Due to the age of the unit, the fact that there were a few things that needed attention, and that the fan was starting to make noises it hadn't before, I decided to replace the unit instead of trying to put new parts into an old unit. I called Mainline Plumbing and spoke with John. He asked if I wanted him to come out that same day! I told him that would be great, but since I got the water heater working, had a bucket under it for the drips, and I was at work and couldn't get away, I asked if we could meet the next day. He said yes and he arrived 15 minutes earlier than the agreed time. He even texted me asking if the earlier time was OK. John came well prepared. Our initial meeting was to assess the job and speak about options, and that's all I really expected of the visit. I did my homework the night before and was aware of the product line of replacement units available. John presented me with those options, plus more that he had access to that I didn't! We both agreed on a model, which he knew was in stock, that would work well for us. John then asked if I wanted it replaced that day! John left for about an hour, came back and the unit really was replaced the same day! I didn't time it, but I am guessing an hour to an hour and a half was all that was needed. I expected to have to wait a week or so to get one in, get on the schedule, etc. It was amazing how quickly the work was done. John also ensured the unit was programmed properly for our installation and set the options for what I wanted. John is a pleasure to talk to, knowledgeable, and did great work. I am truly impressed with the experience. I give John and Mainline Plumbing my highest recommendation. read more

Back in January '23 my water softener failed. It was a Saturday and I tried calling the folks who originally installed the water treatment system for assistance but apparently they stopped working on weekends. I found Mainline doing a quick Google search and gave them a call. I cannot praise this company enough! John came out right away - mid appointment on a Saturday no less- and helped take care of the issue I was having. I decided to stick with Mainline as my primary plumbing business and had John come out and install a new softener. His work is absolutely incredible! Extremely meticulous, clean and thoughtful with designing the layout of water flow. During the softener install John recommended that I have my water tested for PFAS since my state covers the cost of the water levels are over a certain threshold. Turns out my water had high levels of PFAS and John made it a point to come out and get my water treatment system setup as soon as possible which was amazing! As I said above I cannot recommend this business enough! Professional, friendly, impeccable work and family owned. When I find a business that is this professional and takes care of their customers I stick with them. I will be having Mainline take care of all of my water and plumbing needs! read more

What an incredible experience we just had with Mainline Plumbing! Keep in. mind that this happened on a Saturday afternoon! Our shower lever handle snapped off at the end of taking a shower. Water was continuing to run into the tub and back into the wall and the ceiling below. What I assumed would be a nightmare on a weekend turned into some of the best customer service we have ever experienced. We called Mainline, John was at our house in 15 minutes, the repair was completed in 1 hour and John spent extra time with us to discuss what he did, why he did it and gave us some helpful suggestions moving forward. The time from the problem occurring to a completed repair was 1:15 minutes, ON A WEEKEND! I'll wrap up with this, Mainline is prompt, professional, incredibly competent and was true pleasure to have in our home! Nothing but satisfied, but more important, grateful to have them! Thank you again John!!!!! read more

I had a fantastic experience with Mainline Plumbing and the lead, John. I woke up to a water leak that was pooling around the base of my boiler, so called them up regarding both this leak and to see if they could replace my water heater at the same time, since it was nearing the end of its life. John was able to come over on the same day, immediately identify the cause of the leak (an old boiler expansion tank), and then replace both the boiler expansion tank and the water heater. In addition to replacing both of those items, he fixed a portion of the existing piping system, which was poorly installed by someone else. Somehow, all of this work took place over the course of only a few short hours as well! I definitely recommend Mainline and will use them again. read more

Back in 1994 on the day before Christmas our well pump failed. I couldn't contact our normal plumber so I called Mainline. They were at the house in a short time and worked in the frigid cold replacing the well pump which involved climbing down a ladder into the well. Since then Rick has been the plumber I call. Not long ago I started having furnace issues after a well known company was unable to maintain it properly. I called Rick and he suggested John Fait. I couldn't have found anyone better. In September 2022 he installed a new boiler and hot water tank to replace my 35 year old boiler. I couldn't be more pleased. His attention detail and preciseness is what this type of work needs. Thank you Rick and John! Kevin Longley read more

We had Mainline come out to check our kitchen sink pipes after I had tried my plumbing skills, did as much as I could but decided to call in the professionals. John Fiat was the man on the spot. He was very professional and understood my problems immediately even when it was a minor issue. He fixed it within minutes, even gave me some plumbing lessons. Then we proceeded to the next project which was my water heater which had been in my house since 2004 and was living on borrowed time. This was replaced the next day after we made our decision. They are not only all that is mentioned above, their prices are fair and I would recommend them. Big thanks to John Fiat. read more

Buyer beware!! 20 calls and still never got through to resolve my issue! The office employee is rude and should quit since she sounds like 100 years old. They have an unprofessional staff and will not return calls. If you need them when it is most important then good luck, they won't show up. Then they just make excuses! I guess they don't realize that it's the customer that pays them. I guess they can be so rude and down right nasty to whomever they chose since they don't care about customers! Google any local place that can do what your looking for and just don't use Mainline Plumbing and Heating in Londonderry NH read more

STAY AWAY! From the on set horrible customer service. Incompetent receptionist, lack of attention to detail. Called me at 10 a.m. the day of my appoint to cancel my job. I told them weeks ago the next day was my home inspection and they did not care about me! Use any other local plumbing and heating company. Suggestion, research top five in the Rockingham County and they won't be on there! Their arrogance and ignorance to their customer shows they don't care! read more

i decided to give this company a two not based on the rating but what the act of number two symbolizes. this has got to be the worst customer experience i have had in all my life! no chance this company is accredited with the bbb or ever will be. go on you tube and learn to fix it yourself. you have a better chance of getting the job done correctly and save yourself the horrific experience of this place! read more

Call Mainline to have them give me a quote on fixing a slow draining sink issue. They arrived on time and we friendly. After short time they told me that the issue was outside the internal plumbing so I will need to contact a septic repair service. I knew that this was a possibility before calling them. Because of their fast curious service I will call them again for my next plumbing repair. read more

Highly recommend Mainline. Woke up last week with no water. Rick and John were at the house by 9:00 and replaced our well pump. Decided to swap out a very old pressure tank to match our new variable speed pump. We now have the best water pressure ever. Good, honest, local, crew out of Londonderry/Derry. We've been using them for almost 20 years because they do quality work. read more

We had a great experience with Mainline Plumbing Heating. Our water heater had a slight leak and it needed replacing. They came when they said they would. Very prompt and exceptional customer service. Everything was to code and the new water heater works great. We would recommend this company without reservation. Feel free to contact for your future plumbing needs. read more

Highly recommend! Mainline plumbing did a fabulous job. From a review of our well/water sys, recommending options, to the completion of the work, we couldn't be more satisfied. no hard sell, no pressure to purchase anything. Just fair, honest and ethical. and took a lot less time to complete than we had expected. Thank you. read more

If I could put zero stars I would but Yelp won't let me.The woman who answers the phone should be fired! No customer service skills whatsoever. Called in for simple question and she could not answer it. Then said she would have another person call me to answer my question. Yet no one ever called back! read more

Mainline is my #1 go-to service provider. They ways provide excellent customer service, they're trustworthy, knowledgeable and reliable. I always appreciate the extra time they take to communicate with me about exactly what the issue is and how it's going to be repaired. Very highly recommended! read more

John of Main Line Plumbing & Heating performed our annual furnace cleaning. We are extremely satisfied with the service and responsiveness of Main Line. John took the time to explain what was done, boiler efficiency rating and even changed out our big blue filter, as an added bonus. read more

Called late in the afternoon on a Wednesday and John was there between 8 and 10 the next morning, as promised. Professional work and professional attitude. Water back after fairly involved job. We highly recommend. read more

I called John as our ejection pump was failing. He was here within the hour and had a new one installed quickly. Great service!

Mainline is the only company I'll trust with my plumbing issues. They always go above and beyond. I recommend them 100%