Outstanding service. Clean. Reliable. Courteous. Pleasant. Thrilled we found him. Mark fixed two water heaters that were installed wrong. Would call him in a minute. read more

Mark is the best, I decided not to use a big corporate plumbing company and couldn't be happier that I did. Mark is a true tradesman. He treated m home and my job as if it were his own. He put in a tankless water heater for me and not only was he super price competitive but his work and attention to detail was top notch read more

Mark One Plumbing - Navien Tankless Water heater - Plumbing Near Me - Phoenix, Arizona

Mark is very knowledgeable and professional. We lost a 75 gl. and 50 gl. water heater on the same day! Mark helped us see that a 75 gl. replacement tank did not make sense since we are empty nesters. That alone saved me $1K. We replaced the 50 gl. with a tankless system. He is a craftsman. The quality of his work from start to finish was impeccable. By the way his total costs were way less than the corporate plumbing outfits. read more

Mr. Mark Williams is the best! He did the periodic maintenance on our Navien tankless water heater in a thorough manner. He's an authorized installation and service person for many makes of tankless water heaters. Additionally, I asked him to check out the "sewage smell" in our master bath sinks and shower. He did a fantastic job trouble-shooting the problem, cleaning out the pipes and explaining where the odors were coming from. He showed me how to keep those hard to reach areas, such as the sink overflow, clean and odor-free. Mark left our water heater and master bath areas cleaner than he found them! He even wore booties! Finally, we've found a great, responsive plumber. read more

As a Facilities mgr. - Great service. Mark showed up when he said he would and conducted himself in a most professional manner. i'd highly recommended anyone to use Mark One Plumbing. read more

Mark Williams from Mark One Plumbing did an excellent job installing a new hot water heater and changing out some old valves at my home. His work was very clean and top notch. I would highly recommend Mark One Plumbing! Thank you Mark! read more

Very professional from 1st call to follow up after completing job. Installed a tankless hot water system and a water treatment system. Both look & work great. Highly recommend Mark. read more

Mark was great. My wife and I have a tankless water heater that we installed when we moved into our home 15 years ago. It has always had issues, especially in the Summer running hot and cold and failing to keep a steady temperature when taking a showing in our master bathroom. Over the years, I searched on the internet for solutions, asked some friends and even had a plumber look at it without any success in solving the problem. Recently, the problem got worse so I thought that changing the old valve in the shower might correct the issue. To my disappointment, that did not fix the issue. This was extremely frustrating to my wife, who loves her hot showers. Because of the frustration it caused my wife, it became frustrating to me. She has never been a fan of the tankless water heater because of its failure to deliver a steady flow of hot water. Which was odd, because a steady flow of hot water for as long as you want it is what tankless water heaters are supposed to excel at. I got on the manufacturer's website to search for a solution and found Mark One Plumbing as a recommended plumber. I called Mark and found him to be friendly and helpful. He had some initial questions and asked me to check a couple of items that would help him know what he was looking for. Mark thanked me for the information and said he would check the system to see if there were any error codes the system was giving when her arrived. When Mark came out he diagnosed the problem quickly. He noticed that the plumber had installed an unnecessary mixing valve coming from the water heater to the hot water supply to the house. Essentially, the unit was correctly heating the water to 120 degrees and then mixing with the cold water supply, bringing the temperature down as the hot water was coming from the unit and going into the hot water supply to the house. At the shower valve the hot water was then being mixed again with the cold water supply, causing the frustrating fluctuation in temperature. Mark quickly, expertly and efficiently fixed the issue. Additionally, I asked Mark about a leak I was seeing in the new valve I had installed in the master shower. I thought the valve was leaking. It turns out it wasn't the valve, it leaking from the head that I had not tightened enough. Mark quickly fixed that problem and the head is no longer leaking. Mark is also honest. When I asked him to come out, I asked if he would service the water heater, while he was here just to make sure everything was running correctly. When he diagnosed the problem of the unnecessary mixing valve, he told me the machine wasn't giving any error messages and that he could service it, but that everything looked to be running properly and that he didn't think a service was necessary. I had a good friend that was our plumber for years. Ever since he got out of the business, I have been looking for a go to plumber to help me when we have a plumbing issue. Mark is now that plumber. Thanks for the expert and honest help, Mark. You will be the plumber we call on from now on. read more

Mark Williams has done an absolute fantastic job in getting us back online with hot water! Needless to say, it always seems that home nightmares happen during the worst of times. Ours happened the first thing Saturday morning when we realized we had no hot water in the house. Thinking this was odd I headed out into the garage to see what was going on with the hot water heater. Well the first thing I noticed was a hissing sound when I opened the door. Not 100% certain what the sound was, I started to smell if I noticed any gas within the garage, thinking that the pilot light may have gone out and the water heater was spewing gas. Realizing that we didn't have a gas leak, and starting to not panic quite so much, I then walked deeper into the garage and noticed water spilling out from the hot water heater. Great I tell you, just great. No hot water for the weekend is what goes thru my mind. Well we started the morning calling a few plumbers - as well as our home warranty; I then was able to see who was responsive and willing to help out on a Saturday. Fortunately it was my lucky day and Mark was able to come over. Mark is a very stand out guy. He came prepared to see what was wrong, and said that our hot water heater had hit its end of life. I told him that I was interested in a tankless water heater, assuming they were reliable and had a good track record, or potentially replacing the 75-gallon tank with a new one. After a little research, I opted to go with a tankless (to free up space in the garage, as well as the 15 year warranty - and potential to save money over the LONG term...) Mark checked to make certain that we had a large enough gas line, as well as enough pressure from the curve to provide adequate water pressure to the device. He also informed us that a single unit would likely provide adequate heating for our needs, but if we "stress the system" we could run into a reduction in pressure to the devices we would be heating, but a second system would fix this. Mark did a great job in installing the unit, and it even passed my muster, as I'm one who is looking for perfection. I was a little hesitant to select Mark at first, as I was unable to find his business on yelp, but did see a Google recommendation that helped out some. Mark was not the only plumber to come to our home - 4 in total did, one being the home warranty company. In dealing with the home warranty company from a previous repair, I was not too exited to leverage them, plus they were not the friendliest people to come out, but they were CHEAP. This had me worried and in learning more about plumbing, I was realizing they were only going to "replace the unit and not bring it up to code." The next company had a fair price, just like Mark One, yet they were very negative towards certain tankless water heaters - and in researching the one they thought was not a reliable company, I came to realize that it was based on 8 year old technology. The water heater we selected had excellent reviews from third party resources, as well as multiple environmental accolades. They also didn't go as far into validating if a tankless would be a good fit for our home. The last company provided me the reason's why the water heater we selected was not good "8 years ago" but said they are rock solid today and that he highly recommends them to others. He also informed me that they installed multiple tankless units and the pro's/cons of each. They talked heavily about how clean/professional their work would be, as well as their high rating on yelp (they are 5 stars) but their pricing was ~30% higher than the average. I started to wonder if it was worth 30% more to go with them due to their ratings, but felt that Mark provided the same professionalism, same meticulousness, as well as more knowledge about how the tankless water system would work in our home. So I bit the bullet and asked for him to perform the job. Mark called me exactly when he said he would, arrived on time and the installation was done very well. After installing the system he even troubleshot a cross-over line within the home which was causing cold water to go into the hot water line. All in all I have been very impressed. ** As a side note I rely on yelp on a daily basis, and this is the first review I am writing. I truly believe that Mark Williams from Mark One Plumbing did a spectacular job, and that anyone using his services will be pleasantly surprised by his work. read more

Mark Williams at Mark One Plumbing is The Absolute Best for all of your Plumbing Needs! His attention to detail and customer service is Top Notch! He arrived On Time and completed the Job in a timely manner. I would recommend Mark at Mark One Plumbing! read more

Our tenants lost hot water and we received Mark's information by referral from another plumber who could not work with tankless water heaters. He is very knowledgeable, friendly and prompt with more than reasonable pricing for his expertise. We had been told by a previous contractor that the entire unit needed to be replaced- a job that would cost thousands, and Mark was able to get the unit up and running for a very small fraction of that price. He took the time to give us detailed information on the issues so we understood thoroughly which was very helpful since we've lost hot water there on multiple occasions. We'll definitely hang onto his information for future needs. read more

I agree with he other reviews. This is the third time that we have used Mark's services. He is "very" professional and fast, and shows up on time. He also returns calls promptly. He is on our "good guy" list. We have had some VERY bad experiences with plumbers in the past but Mark One is first rate. read more

Mark was fast, efficient and cost effective to my needs when my water heater decided to start leaking. The model of heater was not available, this would have been easy for anyone else to simply tell me to wait until one came in stock, but Mark went out of his way to find a larger unit of the same make and model and installed that for me. I was up and running with hot water the same day. Mark was clean and tidy and I would recommend him to anyone else. Thanks Mark! read more

Mark Williams has been my only plumbing choice for years. He is responsive, does high quality work (and guarantees it!), and leaves everything in perfect order. He brings the same dedication and craftsmanship whether the job is big or small. It's rare in this day and age to find such a solid, competent tradesman. read more

I've never left a bad yelp before but ..... I am really frustrated and disappointed. We had water on the floor after the washing machine went through a cycle. Looks like it's been happening for a while now since we noticed the wood floor and drywall seemed damp. My husband called Mark and he came out, took a look with his flashlight, did not move the washing machine to check behind it, replaced the hot and cold hoses, ran a snake through the drain said it was clear and charged us $150. Assuming that must have been the problem and Mark had fixed it, I ran a load of wash and oops .... More water on the floor, no change at all. We called Mark again and he told us he was a plumber and we probably needed a washing machine repair guy. Ok, so we called the repair guy and he took the washing machine apart, ran it through a cycle and there was NO PROBLEM with the washing machine. He did find the problem though. A pipe in the wall was leaking and needed to be repaired. He cut the drywall easily because it was soft from the leaking and showed me the water gushing out of the pipe when we ran the cycle. I even took a video of it. Guess what, the repair guy said my washing machine is just fine, what I need is a plumber!!!!!!!! This guy spent an hour diagnosing the problem charged me a well deserved $75 for the service call. I will call the plumber he has recommended. Thanks for nothing Mark!!!!! read more