John of 1 Backflow Plumbing has saved us multiple times over the last several years. He is responsive, diligent, honest, and excellent at his work. When you call, he answers the call. Recently, we experienced a horrific plumbing issue in a rainstorm just 2 days before our daughter was coming home for the winter holidays. We were also hosting house guests that week and we were panicked as our showers and toilets were dysfunctional throughout the house. John was there for us immediately. He made sure the problem was properly fixed to our satisfaction and followed up multiple times to make sure all was fine. I highly recommend 1 Backflow Plumbing.

John Cook did all the plumbing work in my house in San Francisco. This was a big job consisting of 3 bathrooms and kitchen. During my interview process, John took notes as to what I wanted done. John email the proposal with a full explanation of the work, cost and timing. I had work with many contractors and never had one that fully listen to my demands. The proposal clearly show John paid attention. The icing on the cake was a job well done and completed on time. In fact, there were issues discover during the demo process which would have cost me more money but John took care of them and did not charge me.

I can't say enough about Johns professionalism, he picked up the phone right away, and was able to certify my back flow devices the very same day, I didn't expect that, but it sure was nice not to have to wait for someone. The best thing is that John will invoice you where some companies want their money up front, I manage HOAs and we don't have a credit card, so money up front is virtually impossible for me. If you have back flow devices, John is the one to certify them as necessary for SFPUC. Thanks for your great service John, and making things very easy, I will call you every year.

My water heater was leaking so I called some plumbers that I found online . Most of the plumbers either referred me to an appointment and didn't call me back or told me they couldn't give me a ballpark estimate to install a standard residential water heater . When I called One Backflow Plumbing , John answered and was very considerate and professional . He gave me an estimate , came the next day on time and completed the job and some extras quickly and professionally leaving no mess . I will recommend One Backflow to my friends and family as a trustworthy contractor .

John is an absolute professional. He went above and beyond the work that I had hired him to do. He is extremely knowledgeable and talented in plumbing, as well as many other aspects of home maintainence, repair and improvement. I have definitely added him to the short list of trusted tradesmen, of whom I’ll have work on my property again.

John is the owner and does the work himself. He installed a new water heater for me. He is very experienced, professional and explained everything thoroughly. He used to build homes in the past and I picked his brain on a few other projects I am planning around the house - he was happy to help and offered great advice!

John is the best! Super responsive, great communication, high quality workmanship, and overall great guy! Have hired him for 3 jobs over the last couple years. Had him install a tankless water heater, repair and replace a busted spigot, and replace a faulty valve on another tankless water heater that was leaking.

I manage a rental property in Menlo Park and have been using 1 Backflow for years. :). Amazing! I have found that it’s hard to find people that take pride, have honesty and integrity in what they do but 1 Backflow has it all. Whether it’s an emergency or a minor fix, you can trust them to do a great job!!

Good service, came prepared and figured out how to unplug 2 interior downspouts three stories up. No BS just hard work! Heads and shoulders above others who had “looked” at the job.

They do the backflow test for a commercial space every year and we will continue to use them. Great company which is easy to work with.

We use 1 Backflow Plumbing every year for the city inspection, and they are always very easy to deal with and very efficient.

John came on time, was knowledgable and fair, worked through a rain storm and did work at a fair price. Couldn't be happier.

These guys are great. They use technology to improve the entire experience, are on time and on schedule. Love these guys.

They took care of the backflow report required by San Francisco and they were quick and timely.

Annual backflow inspection for our boiler. Easy to schedule online, and was done in a jiff.

Excellent service! Perfect. On time, knowledgeable and and quality work. Thanks so much.

Very happy with this company and have used their services for my annual backflow test.

Super easy to work with, professional and prompt. Couldn't ask for better service.

on time professional backflow assessment Excellent service

Very personable and capable; I was very satisfied.

Knowledgeable and attentive. Highly recommend!

So quick, professional and reasonably priced!

Great service super fast and great knowledge

Always adds something useful to the visit!

Adrian was very prompt and thorough!

very good service. thank you!

great service as usual.

Backflow Water Testing

Excellent work .