Quick answer
Most Montgomery County homes on WSSC Water don't need a water filtration system for safety, because the water is treated and tested. People add one for taste, chlorine smell, scale from hard water, or extra protection from older home plumbing. Homes on a private well are different: test the water first, then choose treatment that matches the results.
| Under-sink carbon filter | Under-sink reverse osmosis | Whole-house filter | Water softener | |
|---|---|---|---|---|
| Main job | Taste, chlorine, some contaminants (check certification) | Drinking water at one tap, removes the widest range | Chlorine and sediment for the whole house | Hardness (scale) |
| Treats | One faucet | One faucet (sometimes the fridge) | Every faucet | Every faucet |
| Helps with lead from home plumbing | Yes, if certified for lead | Yes, if certified | No | No |
| Space needed | Under the sink | Under the sink, plus a small tank | Near the main water line | Near the main water line, plus a drain |
| Upkeep | Change cartridges | Change filters and membrane | Change cartridges | Add salt, occasional service |
| Relative cost | Lowest | Moderate | Moderate to higher | Moderate to higher |
Is the tap water in Montgomery County safe without a filter?
If your water comes from WSSC Water, it is treated at a filtration plant and tested before and after it reaches homes. WSSC publishes the results every year. In its 2025 tap water analysis, lead was not detected in the treated water leaving either plant, and in the most recent required lead sampling (2023, reported in that analysis), 0 of 69 sites tested were above the lead action level.
So for most homes on public water, a filtration system is about preference and protecting your plumbing, not about making unsafe water safe. The exceptions are homes with old plumbing that may contain lead, and homes on private wells, which nobody tests for you.
What problems does a water filter actually fix?
Start with the problem, not the product. The CDC's advice is to know what's in your water first, then choose a filter that is certified to remove that specific thing.
- Chlorine taste or smell: a carbon filter at the kitchen sink or a whole-house carbon filter. Treated water carries a small amount of disinfectant so it stays safe in the pipes, and some people notice it.
- White crust on faucets, spotty dishes, scale in the water heater: that's hardness. A water softener deals with hardness. A regular carbon filter does not.
- Worry about lead from older pipes or solder: a point-of-use filter at the kitchen sink certified for lead reduction. The EPA notes that whole-house filters don't remove lead that comes from plumbing inside the home.
- Wanting the cleanest possible drinking water: an under-sink reverse osmosis (RO) system for the kitchen tap.
- Well water with bacteria, iron, sulfur smell or other issues: treatment matched to a lab test of your well.
Whole-house filter, under-sink filter or softener: what's the difference?
These three get mixed up a lot. They do different jobs, and many homes only need one of them, or none.
There's no single best system. The right choice depends on your water, your plumbing and how much space you have. For whole-home filtration, one system we commonly install is Aquasure, but we'll recommend what fits your home.
How hard is the water in Montgomery County?
WSSC Water treats water from two rivers. In its 2025 tap water analysis, water from the Potomac plant averaged 154 mg/L of hardness, and water from the Patuxent plant averaged 70 mg/L. By the U.S. Geological Survey's scale, 154 mg/L is hard and 70 mg/L is moderately hard.
Depending on where you live, your water may come mainly from one plant or a blend of both. If you see scale building up on shower glass and faucet aerators, or your water heater is noisy with sediment, hardness is the likely cause. A softener is the fix for that, not a filter.
Bethesda, Potomac, Germantown, Gaithersburg and Silver Spring: what's different?
- Bethesda and Silver Spring: many homes here are older. If your house still has original galvanized pipes, a lead service line, or lead solder on copper pipes, a certified point-of-use filter at the kitchen sink is a sensible extra layer. A plumber can tell you what your pipes are made of.
- Potomac: some Potomac homes are on private wells. Nobody tests a private well for you, so get a lab test before you buy any treatment. Well water problems like iron, sulfur smell or bacteria need equipment chosen for that water.
- Germantown and Gaithersburg: most homes here are on WSSC Water, and many are newer. The usual reasons to add treatment are scale from hard water and taste.
- Townhomes and condos in all five areas: space is tight. An under-sink filter or RO system usually fits where a whole-house system won't.
What does NSF certification mean on a water filter?
Look for a filter certified by NSF International or another accredited lab for the exact contaminant you care about. Certification is specific: a filter certified for chlorine taste is not automatically certified for lead.
NSF/ANSI 42 covers aesthetic effects such as chlorine taste, odor and particulates. NSF/ANSI 53 covers contaminants with health effects, such as lead. NSF/ANSI 58 covers reverse osmosis systems. Check the product's listing, not just the box, to see which contaminants it was tested for. For lead, the EPA recommends a point-of-use filter certified to NSF/ANSI 53 for lead reduction and NSF/ANSI 42 for particulate reduction (Class I).
What does a filtration system need after it's installed?
Change cartridges on the manufacturer's schedule. The CDC notes that regular changes help keep germs from growing in the filter. Softeners need salt. RO systems need filter and membrane changes and a little space for a storage tank under the sink.
Before you buy, ask how often the filters need changing, what they cost, and whether you can change them yourself. That ongoing cost matters as much as the price of the system.
Montgomery County specifics
- WSSC Water's 2025 tap water analysis reported average hardness of 154 mg/L for the Potomac plant and 70 mg/L for the Patuxent plant.
- In the same analysis, lead was not detected in water leaving either plant, and in the 2023 lead sampling it reports, 0 of 69 distribution sites were above the lead action level.
- The U.S. Geological Survey classifies water at 61 to 120 mg/L as moderately hard and 121 to 180 mg/L as hard.
- Private wells are the owner's responsibility to test. The EPA recommends testing well water regularly.
Is this not for you?
If your water tastes fine, your fixtures don't build up scale, and you're on WSSC Water in a newer home, you may not need any treatment at all. A pitcher filter for the fridge is a cheap way to test whether you notice a difference. If your concern is a specific contaminant in well water, start with a certified lab test, not a plumber. And if a company offers a free in-home water test that ends with a hard sell, ask for the results in writing and compare them with WSSC's published report.
Frequently asked questions
Is WSSC tap water safe to drink?
WSSC Water treats and tests its water and publishes the results every year. In its 2025 analysis, lead was not detected in water leaving either treatment plant. Older homes can still pick up lead from their own plumbing, which is why a certified kitchen filter can make sense there.
Does a whole-house filter soften water?
No. A whole-house carbon filter mainly reduces chlorine and sediment. Hardness minerals pass through it. If scale is your problem, you need a softener.
Is reverse osmosis worth it?
It's worth it if you want the cleanest drinking water at the kitchen tap and have room under the sink. It treats only that one faucet, and it needs regular filter changes. For taste alone, a simpler carbon filter is often enough.
How do I test my water?
On WSSC Water, start with WSSC's published water quality report. For lead from home plumbing or for a private well, use a state-certified lab. The CDC and EPA both recommend testing before choosing a filter.
Can a water softener damage my plumbing or water heater?
A properly sized and set softener generally protects the water heater and fixtures from scale. Follow the manufacturer's settings and the water heater manual, since some manufacturers have guidance about softened water and the anode rod.
Do I need a filter on well water in Potomac?
Maybe. It depends entirely on what's in your well. Test the water first, then choose treatment for the problems the test finds. Testing again every year is a good habit.