Reverse Osmosis Maryland — Under-Sink RO Systems
Reverse Osmosis
Maryland Well Water
Under-sink RO systems that remove nitrates, arsenic, PFAS, heavy metals, and dissolved solids from your well water. Installed correctly — with the right pre-treatment for Southern Maryland water chemistry. Licensed Master Plumber Terry Foster (#98433).
What Reverse Osmosis Removes from Maryland Well Water
RO membranes remove contaminants by forcing water through a semi-permeable membrane that blocks dissolved solids and many contaminants. Here's what an RO system removes — and what it doesn't:
What RO Removes
- Nitrates and nitrites (common in agricultural areas)
- Arsenic (naturally occurring in some Maryland aquifers)
- PFAS / PFOA (emerging contaminants)
- Lead and other heavy metals
- Fluoride
- Dissolved solids (TDS)
- Chlorine and chloramines
- Sodium
- Many pesticides and herbicides
- Radium and other radioactive particles
What RO Does NOT Remove (Requires Pre-Treatment)
- Iron — must be removed upstream or it fouls the membrane
- Hydrogen sulfide (sulfur smell) — dissolved gas passes through membrane
- Bacteria and viruses — requires UV disinfection upstream
- Sediment — requires sediment pre-filter to protect membrane
- Hardness minerals — softener upstream extends membrane life
Important: For Southern Maryland well water with high iron, an iron filter must be installed before the RO system. We always design the full treatment sequence — not just the RO unit.
RO Systems We Install
Under-Sink 5-Stage RO System
Best for: Most Maryland homeowners — drinking and cooking water at the kitchen tap
Sediment pre-filter → carbon pre-filter → RO membrane → post-carbon filter → storage tank. Produces 50–100 gallons per day. Connects to a dedicated faucet at the sink and can feed a refrigerator ice maker line. Annual membrane replacement recommended.
Typical cost
$600–$1,200 installed
Under-Sink RO with Remineralization
Best for: Homeowners who want RO water quality but prefer the taste of mineral water
Same as 5-stage system with an added remineralization stage that adds calcium and magnesium back to the water. Improves taste and raises pH slightly. Good option for homes with very high TDS where the RO water tastes flat.
Typical cost
$700–$1,400 installed
Tankless RO System
Best for: Limited under-sink space, or high-volume households
Produces RO water on demand without a storage tank. Faster flow rate than tank-based systems. Requires more counter/cabinet space for the unit but eliminates the storage tank. Good for households that use significant volumes of RO water.
Typical cost
$800–$1,500 installed
RO + Iron Filter Package
Best for: Southern Maryland well water with elevated iron (most Calvert County homes)
Iron filter installed upstream of the RO system to protect the membrane from iron fouling. We design the full treatment sequence based on your water test results. Iron filter + RO is the standard recommendation for Calvert County well water.
Typical cost
$2,000–$3,500 installed (iron filter + RO)
Prices are estimates. We provide a written estimate after testing your water and evaluating your installation. Prices include installation labor and all fittings.
Why Southern Maryland Homeowners Choose RO
Nitrates from Agricultural Runoff
Charles County and parts of Anne Arundel County have elevated nitrate levels in some wells due to agricultural activity. Nitrates are a health concern, particularly for infants. RO is the most effective treatment for nitrate removal — ion exchange softeners do not remove nitrates.
High TDS and Mineral Taste
Calvert County well water often has high total dissolved solids (TDS) from the Aquia aquifer. High TDS produces a mineral or salty taste. RO removes dissolved solids and produces clean-tasting water. Many homeowners use RO for drinking and cooking even when their whole-house treatment is working well.
PFAS Concerns
PFAS (per- and polyfluoroalkyl substances) have been detected in some Maryland groundwater sources. RO is one of the most effective treatments for PFAS removal. If you are concerned about PFAS in your well water, we can test for it and recommend appropriate treatment.
Arsenic in Well Water
Arsenic occurs naturally in some Maryland aquifers, particularly in older geological formations. The EPA maximum contaminant level for arsenic is 10 ppb. RO removes arsenic effectively. We test for arsenic as part of our comprehensive water test.
Frequently Asked Questions
What does reverse osmosis remove from well water?
Do I need a whole-house RO system or just under-sink?
Can I install RO on well water with high iron?
How often does the RO membrane need to be replaced?
Does RO water taste flat?
What Southern Maryland Homeowners Say
Real reviews from well water customers across Calvert and Anne Arundel County.
Jess
Local Guide
Southern Maryland
May 2026
"We had a mystery leak in our bathroom and everyone who saw it was convinced it was coming from inside the wall. He came out, checked everything, and was super thorough instead of just guessing. Turns out it was actually a leak from the toilet tank that was dripping in a way that made it look like it was coming from the opposite wall. He was super patient with all of our questions and explained the fix. We really appreciated his professionalism and transparency. Having an older home, it can be stressful not knowing what kind of repair you're walking into. I highly recommend him if you want someone trustworthy and knowledgeable who genuinely just wants to help."
Bruce Bennett
Southern Maryland
June 2026
"When our well stopped working, Deep Dive Plumbing came out quickly, diagnosed the problem, and fixed it right away. I was impressed by their honesty, professionalism, and willingness to drop what they were doing to help us. The issue was diagnosed correctly, repaired efficiently, and the entire experience was stress-free. I truly appreciated the way I was treated throughout the process and the confidence they gave me that the problem was fully resolved. I would highly recommend Deep Dive Plumbing for any plumbing or well system repairs, large or small."
Christina
Southern Maryland
June 2026
"By far, hands down, the best customer service I have experienced. The technician from Deep Dive Plumbing Maryland was incredibly helpful, professional, and patient throughout the entire process. He quickly assessed the problem, explained what was causing it, and carefully removed the cover without damaging anything. It's rare to find companies that combine technical expertise with genuinely outstanding customer service, but Deep Dive Plumbing Maryland absolutely delivered on both."
Ready for Clean Drinking Water?
We test your water first, then design and install the right RO system for your water chemistry. Written estimate before any work begins.