Once you’ve decided to invest in a water filtration system, the next question is whether to install a whole-house system or a point-of-use filter under your kitchen sink. Both improve your water quality, but they work differently and serve different purposes. Here’s how to choose the right one for your Maryland home.
Whole-House Filtration: Clean Water at Every Tap
A whole-house water filtration system installs at the main water line where it enters your home. Every drop of water that flows through your plumbing—from kitchen and bathroom faucets to showers, laundry, and outdoor hose bibs—passes through the filter first.
What whole-house systems remove:
- Sediment and particulates
- Chlorine and chloramines (improving taste and reducing skin irritation)
- Iron and manganese (preventing staining)
- Some VOCs and organic compounds, depending on the filter media
Best for: Homes where you want consistent water quality everywhere—especially if you notice chlorine smell in showers, sediment in your water, or iron staining on fixtures and laundry. Whole-house systems also protect your plumbing and appliances by filtering sediment before it reaches your pipes, water heater, and washing machine.
Under-Sink Filtration: Targeted Drinking Water Treatment
Under-sink systems install beneath your kitchen sink and filter water at a single point of use—typically your kitchen faucet. The most common type is a reverse osmosis (RO) system, which pushes water through a semi-permeable membrane to remove a wide range of contaminants.
What under-sink RO systems remove:
- Lead and heavy metals
- PFAS (forever chemicals)
- Nitrates and arsenic
- Total dissolved solids (TDS)
- Bacteria and microorganisms (when combined with UV treatment)
Best for: Homeowners primarily concerned about the quality of their drinking and cooking water. RO systems provide the highest level of contaminant removal available for residential use, making them ideal for families with health concerns or homes with well water.
Can You Use Both?
Absolutely—and many Maryland homes benefit from this layered approach. A whole-house system handles the heavy lifting by removing sediment, chlorine, and iron throughout your home, while an under-sink RO system provides an extra level of purification specifically for drinking water.
This combination is especially common in the Frederick and Woodbine areas where homes on well water may deal with sediment, iron, and other contaminants that a single system can’t address completely. Even homes on municipal water in Gaithersburg and Rockville benefit from this approach, particularly if you want both whole-home chlorine removal and high-purity drinking water.
Cost and Maintenance Comparison
Whole-house systems typically cost more upfront and require filter changes every 3 to 6 months, depending on your water quality and usage. The filters themselves are relatively affordable and the process is straightforward.
Under-sink RO systems have a lower upfront cost but involve multiple filter stages that need replacement on different schedules—pre-filters every 6 months, the RO membrane every 2 to 3 years, and the post-filter annually. They also produce wastewater as part of the filtration process, though modern systems have improved their efficiency significantly.
Get a Professional Recommendation
The best starting point is always a professional water quality test. At Mallick Plumbing & Heating, we test your water, review the results with you, and recommend only the filtration setup your home actually needs. We install and service whole-house systems, reverse osmosis units, UV purifiers, and water softeners throughout Gaithersburg, Frederick, Rockville, and the surrounding Maryland area. Contact us to schedule your water test.