Legally Certified
Maryland-certified Backflow Testers on staff — the licence the law actually requires.
Commercial Backflow Prevention & Testing In Gaithersburg, MD
Commercial backflow prevention across Gaithersburg, Maryland and D.C. — installation, repair, maintenance and certified annual testing by Maryland-licensed Backflow Testers, with the certification issued.
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Backflow Prevention Service in Gaithersburg
Commercial backflow prevention in Gaithersburg
Backflow is the accidental reverse flow of water through a plumbing system, and on a commercial property it is a regulatory matter as much as a plumbing one. When it happens, non-potable water moves the wrong way and mixes with the drinking supply.
Mallick provides commercial backflow prevention across Gaithersburg, Maryland and D.C. — device installation, replacement, repair, maintenance and certified testing.
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One Contractor
Test and repair in one visit, rather than a test that hands you to another contractor.
Compliance Diarised
Retest dates scheduled, so annual compliance does not lapse unnoticed.
Annual test due, or a device that has failed? Maryland requires a certified Tester.
Call (301) 804-6759Worth Knowing
Maryland requires a certified Backflow Tester
Under Maryland law, only a licensed Backflow Tester may service backflow preventers. A Tester must be at minimum a Journeyman Plumber who has completed a State of Maryland-sanctioned 40-hour certification course for Cross-Connection Technicians, and must be recertified every three years.
That is a meaningful bar, and it is worth checking before engaging anyone. We hold certified Backflow Testers on staff, so testing, certification and the repair that may follow are one visit and one contractor rather than two.
Project control
How a commercial backflow job runs
Backflow is a pressure event: either pressure rises on the wastewater side, or — far more commonly — it drops on the supply side and water is drawn backwards.
The supply pressure can drop for a broken water main, plumbing work that drains a property, a widespread power outage, firefighters placing heavy demand on the local supply, or a new piece of water-using equipment changing the balance. Almost none of these can be prevented by the property owner. The device is what controls the consequence.
Site surveyed
Cross-connections identified across the site — irrigation, boilers and handheld outlets are where the real risk is.
Devices specified
Correct class of device specified for each connection, rather than a default check valve everywhere.
Tested and repaired
Tested by a Maryland-certified Backflow Tester, with any repair or replacement handled on the same visit.
Certified and diarised
Certification issued and the retest date scheduled, so compliance does not lapse quietly.
Worth Knowing
Where the risk sits on a commercial site
On commercial property the risk concentrates around irrigation systems and hose bibs, boilers and radiators, and any handheld outlet that can reach standing water. Irrigation is the one most often overlooked and the highest risk of the three.
When the device detects a pressure reversal, a check valve closes and stops flow going the wrong way. A check valve is not the only type of preventer, and the correct class depends on what is on the other side of the connection — which is a decision worth getting right rather than defaulting.
Why Mallick
Maryland Has Trusted Mallick For 30+ Years
WSSC-licensed and insured crews, and warranties in writing: one year on installations, 30 days on repairs. The same standard whether it is a backflow prevention call at 2pm or a burst line at 2am.
Google reviews
2,979
4.9 average across Gaithersburg, Frederick and Woodbine
Customer Field Notes
What Customers Remember After The Call
4.9
2,979 Google reviews across three Maryland locations
Field note 01 · Gaithersburg, MD
“Eric and Nick did a wonderful job.”
Very thorough and provided detailed explanation of what was needed to get our garbage disposal up and running.
Abbas and Koli were great technicians.
Quickly diagnosed the issue, thoroughly explained everything, and gave me a few options to move forward. I've had great experiences working with Mallick, highly recommend.
Chrissie Schenkel · Gaithersburg, MD Abbas came to our house for an emergency repair on a Saturday.
He was courteous and kind, he didn’t rush, and he worked hard to fix our problem and thoroughly investigate. It was hard to find a plumber who could do this on a Saturday at the last minute, and we appreciated Mallick’s and Abbas’s willingness.
Raj Nayak · Gaithersburg, MD Abbas Rahimiari was exceptionally professional, looking at our two plumbing problems, describing the underlying issues, fixing one immediately and explaining options on the other. Courteous, clear and efficient. And knowledgeable.
Gordon Schatz · Gaithersburg, MD I had a wonderful experience with Billy.
He was amazing and he was able to fix my issue with no concerns! 10/10! Thank you Billy.
Mia Barker · Gaithersburg, MD Excellent service and support from William Clem and Malick Plumbing.
Had a pinhole leak in a water service line. Found and fixed the problem … thanks so much.
Daryle Seckar · Gaithersburg, MD Roberto and Adelson were great to work with, efficient, and answered all questions. Top service and repair of water heater!
Jonathan Daly · Gaithersburg, MD
Fred and Luka were great!
They took the time to find the issue as well as helping me get opinions on future concerns as a new homeowner! Real experts and will work with them again!
Elijah Wadsworth · Woodbine, MD Abbas and Koli were fantastic.
They quickly identified and resolved our issue, and did a check to ensure there were no other sleeping issues. They were a pleasure to work with, respectful, and kind.
Kelley Barnaby · Gaithersburg, MD I received great service from both Ikem and CJ today.
They quickly identified the leak and fixed the issue. They also did a great job replacing some valves that needed replacing. They were very experienced and efficient. I have used Mallick several times and have always been pleased with their service.
Melissa Cavuto · Gaithersburg, MD Abbas and Erick were professional, knowledgeable and kind.
They inspected and guided me to make safe choices with my range that had a gas leak.
Andrea Huerta · Gaithersburg, MD Abbas and Bryan installed my new water heater.
There was a leak in my furnace and they fixed it also! The job was perfect. They had to install vents that were well done. They left no trace and the house was completely clean. The new water heater works like a charm. HIGHLY RECOMMEND this team and Mallick.
Janet · Gaithersburg, MD Kyle was so helpful in helping my husband and I fix the water pressure in our house. Kyle was very well versed and experienced, providing great options for future improvements to water filtering. I would highly recommend his services to anybody struggling with plumbing issues.
Azusena Herrera Tapia · Gaithersburg, MD
Every quote above comes directly from Mallick’s current Google Business Profile record.
Read more customer storiesCommon Questions
Backflow Prevention Questions, Answered
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(301) 804-6759Someone picks up 24/7 — nights, weekends, and holidays included.
Who is legally permitted to test a backflow preventer in Maryland?
Under Maryland law, only a licensed Backflow Tester. That means at minimum a Journeyman Plumber who has completed a State of Maryland-sanctioned 40-hour Cross-Connection Technician course and is recertified every three years. It is worth confirming before engaging any contractor for this work.
How often does a commercial backflow device need testing?
Annually in most jurisdictions. A failed backflow preventer is indistinguishable from a working one without testing, which is exactly why the requirement exists. Testing keeps the property compliant and confirms the device is doing its job.
Which parts of a commercial property need protection?
Irrigation systems and hose bibs, boilers and radiators, and any handheld outlet that could reach standing water. Irrigation is both the most commonly overlooked and the highest risk, because the outlet sits at ground level among whatever is on the landscaping.
Can you repair a device as well as test it?
Yes — our Testers are certified, so testing, certification and any repair arising from it happen on one visit with one contractor. Where a device has failed, we can replace or repair it and re-certify rather than handing you back to someone else.
Where We Work
Backflow Prevention Service Across Maryland
Bethesda Rockville Silver Spring Germantown Potomac Olney Clarksburg Damascus Chevy Chase North Potomac Frederick Woodbine Columbia Ellicott City Aspen Hill Boyds Burtonsville Darnestown North Bethesda Poolesville Takoma Park Wheaton–Glenmont White Oak Green Valley Linganore Washington, DC College Park
Related Services
Commercial Plumbing Commercial plumbing for restaurants, retail, offices and multi-unit buildings across Gaithersburg and Montgomery County — grease traps, backflow prevention, storm drainage, commercial water heaters and 24/7 emergency response.
Residential Backflow Prevention Backflow prevention device installation, repair and certified testing in Gaithersburg and across Maryland — protecting the drinking supply, and producing the certificate that proves it.
Commercial Sewers Commercial sewer cleaning, inspection, repair, replacement and maintenance across Gaithersburg and Maryland — sequenced to get the property trading again first and do the permanent repair second.