The Right Problem
Tested before specified. Reverse osmosis fixes taste and dissolved solids, not hardness — we will say which you have.
Reverse Osmosis Systems In Frederick, MD
Reverse osmosis systems for Frederick County kitchens — polished drinking water at one tap, on municipal supply or a private well, installed and maintained by licensed plumbers.
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Reverse Osmosis Service in Frederick
Reverse osmosis systems in Frederick
Reverse osmosis is the process behind most bottled drinking water, and it can be installed in a house rather than bought by the case. Household pressure pushes the supply through a semi-permeable membrane that holds back dissolved solids, carbon, calcium, sediment and bacteria, leaving water that tastes like the bottled equivalent without the bottles.
Most homes use an under-sink system for the kitchen tap and fridge line. Whole-house reverse osmosis is a larger system with different installation requirements.
Schedule Reverse Osmosis Service
Tell us what you need — we’ll be in touch fast.
Sized Sensibly
Under-sink where that serves you, whole-house only where it is genuinely warranted.
Maintained On Schedule
Filters and membrane on a schedule, so the system stays as good as the day it went in.
Buying bottled water by the case? We test before we specify.
Call (301) 804-6759Worth Knowing
What the system involves
The equipment is not complicated once installed. Check valves and shut-off valves protect the system if something upstream fails, and with few moving parts the failure rate is low — the consumable is the membrane and the pre-filters, which are replaced on a schedule rather than when something goes wrong.
An under-sink system provides filtered drinking water at the tap and can reduce reliance on bottled water.
Treatment sequence
How a reverse osmosis install runs
Reverse osmosis is the right answer for dissolved solids, taste and drinking-water purity. It is not the answer for hardness — that is a softener — and it is not the answer for biological contamination on a well, which is UV.
We test first so the treatment we recommend addresses the water quality problem actually present.
We test first
We test the water. Reverse osmosis is the wrong tool for hardness or bacteria, and the test tells us which problem you have.
Specified honestly
We size and site the system — under-sink for drinking water in most homes, whole-house only where it is genuinely warranted.
Installed with protection
Installed with check and shut-off valves so an upstream failure cannot take the system with it.
Consumables scheduled
Filter and membrane changes put on a schedule, because that is the only maintenance it really needs.
Worth Knowing
Treating Frederick County water
Water quality matters more in Frederick County than almost anywhere else we work, because so much of the county is on private wells. A well off the Frederick Valley's limestone often runs hard; others pick up iron, sediment or low-pH water that quietly eats copper pipe. None of that is visible at the tap until something fails.
That's why every recommendation here starts with a test. Treating well water without one is guessing with your plumbing — the test says what's in the water, and the equipment follows from the test, not the other way around.
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 reverse osmosis call at 2pm or a burst line at 2am.
Google reviews
2,979
4.9 average across Gaithersburg, Frederick and Woodbine
Code & Permits
Treatment equipment and Frederick County rules
Most treatment installs tie into the home's main supply line, and in Frederick any permitting that plumbing work needs runs through Frederick County Permits and Inspections — or the City of Frederick inside town — rather than WSSC.
On well systems the more important paperwork is the water test itself: it is the record of what the equipment was sized to treat. We test before we recommend, and the equipment follows the test.
Permit and inspection requirements per Frederick County Permits and Inspections. Requirements change — confirm current rules before work.
Ways To Save
Current Offers On This Job
$81
Off
Water Quality Installation
Limit 1 offer per customer, cannot be combined with other offers, residential use only, must be presented at time of service. Not applicable to dispatch charge. Valid Jan 1 – Dec 31, 2026.
Our maintenance plan
The Service Contract Of Choice
A 12-month annual maintenance contract for your home’s plumbing. The team is small enough to give you personalized attention and large enough to handle whatever comes up.
What stands behind every contract
12-month coverage term
24/7 emergency line
Licensed, trained technicians
Payment plans available
2-Year Extended Warranty for Furnished & Installed Equipment
6-Month Repair Warranty
Levels are matched to your home
The office confirms the current contract levels and details before you commit — call and the team will walk you through the options.
12-month term · Sign up by phone
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
Reverse Osmosis Questions, Answered
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How does a reverse osmosis system work?
Household water pressure pushes the supply through a semi-permeable membrane. The membrane holds back dissolved solids, carbon, calcium, sediment and bacteria, and what passes through is the drinking water. Check and shut-off valves protect the system if something upstream fails.
Is reverse osmosis installed whole-house or at one tap?
Most are installed under the kitchen sink, feeding the cold tap and often the fridge line. Whole-house systems require a separate assessment of the property and water supply.
Does reverse osmosis solve hard water?
No. Reverse osmosis targets dissolved solids, taste and purity; hardness is a softener's job. Homes with both problems run both, and the order they go in matters. A water test tells us which you actually have before anything is specified.
What maintenance does a reverse osmosis system need?
Pre-filters and the membrane, on a schedule rather than on failure. Everything else has few moving parts, which is why these systems are reliable — the maintenance is consumables, and skipping it is what turns a reliable system into a slow one.
What should I ask a company that installs reverse osmosis?
Ask whether the company that installs it will also service it, and whether they tested your water before recommending reverse osmosis at all. Filters and membranes are consumables, so an installer who disappears afterwards leaves you with a system that quietly degrades — and reverse osmosis specified without a test may be aimed at the wrong problem entirely.
What's actually in Frederick County well water?
It varies well to well — which is exactly why we test first. Hardness is common off the valley's limestone; iron, sediment and low-pH water show up too. The test names the problem, and the equipment follows from the test.
Can you treat both well water and city water?
Yes. Municipal supply and private wells raise different problems, and the treatment is sized to what the test finds in your water either way — not to what's sitting in a warehouse.
Where does whole-house treatment equipment get installed?
At the main line, usually after the pressure tank on a well system, so every tap in the house gets treated water — not just the kitchen.
Where We Work
Reverse Osmosis 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
Water Quality Softeners, filtration and whole-house treatment for Frederick County water — municipal or private well — sized from a real water test, not a brochure.
Filtration Systems Whole-house filtration for Frederick County water — sediment, taste, odor and well-water problems treated at the main line, chosen from a test rather than a guess.
Water Testing In-home water analysis for Frederick County homes on municipal water and private wells. Understand hardness, chlorine, pH and other characteristics that affect everyday water use.