The water filter that’s perfect for a home on city water could be completely wrong for a home on well water — and vice versa. Municipal water and well water come from fundamentally different sources, go through different (or no) treatment processes, and contain different contaminant profiles. Choosing the right filtration system starts with understanding which source you’re working with and what challenges each one presents.
About 87% of Americans get their water from a public municipal system. The remaining 13% — roughly 43 million people — rely on private wells. If you’ve recently moved from one to the other, or if you’re buying a home and aren’t sure what filtration you need, this guide breaks down exactly how the two sources differ and what each one requires for clean, safe water.
How Municipal Water Gets to Your Tap
Municipal water (city water) is sourced from surface water (rivers, lakes, reservoirs) or groundwater (municipal wells), then processed at a treatment plant before distribution. The typical treatment process includes:
- Coagulation and flocculation: Chemicals are added to bind small particles into larger clumps that can be removed.
- Sedimentation: Heavy particles settle to the bottom of treatment basins.
- Filtration: Water passes through sand, gravel, and activated carbon filters to remove remaining particles.
- Disinfection: Chlorine or chloramine is added to kill bacteria, viruses, and other pathogens. Some utilities also use UV or ozone treatment.
- pH adjustment and fluoridation: Many utilities adjust pH to reduce pipe corrosion and add fluoride for dental health.
After treatment, water travels through a distribution network of pipes — sometimes miles of aging infrastructure — before reaching your home. The EPA regulates municipal water under the Safe Drinking Water Act, requiring utilities to test for approximately 90 contaminants and publish annual Consumer Confidence Reports (CCRs).
How Well Water Gets to Your Tap
Well water is pumped directly from an underground aquifer through a drilled or dug well on your property. A submersible pump (or jet pump for shallow wells) pushes water through your home’s plumbing with no treatment whatsoever — unless you install it yourself.
There’s no treatment plant, no disinfection, no monitoring, and no annual report. The EPA does not regulate private wells. Your state may have well construction standards, but ongoing water quality is entirely the homeowner’s responsibility.
Well water quality depends on your local geology (what minerals and elements are in the rock and soil), the depth of your well (deeper wells are generally more protected from surface contamination), nearby land use (agriculture, industry, septic systems), and the condition of your well infrastructure (casing, cap, seal).
Contaminant Profiles: Side by Side
This is where the two sources diverge most dramatically:
The key takeaway: municipal water’s main issues are the chemicals added during treatment (chlorine, fluoride) and contaminants picked up in the distribution system (lead, disinfection byproducts). Well water’s main issues are naturally occurring contaminants (iron, manganese, hardness, arsenic) and the absence of any disinfection barrier against microorganisms.
Filtration for Municipal Water
City water has already been treated to meet EPA standards, so your filtration goals are typically:
- Remove residual chlorine or chloramine (taste, odor, and potential health effects of disinfection byproducts)
- Reduce disinfection byproducts (TTHMs and HAA5)
- Remove lead (if your home has old plumbing)
- Remove PFAS (if detected in your CCR)
- Optionally remove fluoride (personal preference)
Recommended Systems for Municipal Water
For taste and chlorine only: A simple pitcher filter (Brita, PUR) or faucet-mount filter handles chlorine taste effectively. Cost: $20-$40 plus $30-$60/year in filters. This is the minimum viable filtration for city water.
For chlorine + lead + basic health protection: An under-sink carbon block filter certified to NSF 42 and NSF 53 (like the Aquasana AQ-5200 or Clearly Filtered under-sink system) removes chlorine, lead, cysts, and many VOCs. Cost: $100-$250 plus $50-$100/year in filters.
For comprehensive protection (including PFAS, fluoride, nitrates): An under-sink reverse osmosis system certified to NSF 58 removes 95-99% of all dissolved contaminants. This is the most thorough option for city water. Cost: $200-$600 plus $60-$150/year in filters.
For whole-house chlorine removal: A whole-house carbon filter removes chlorine from all water in the home — showers, laundry, and all taps. This eliminates chlorine exposure through skin absorption and inhalation during showers. Cost: $300-$1,500 plus $50-$150/year in maintenance.
Important note on chloramine: If your utility uses chloramine instead of chlorine (check your CCR), you need catalytic carbon rather than standard activated carbon. Standard carbon removes chlorine effectively but is much less effective against chloramine. Catalytic carbon is specifically designed for chloramine reduction. Not all whole-house carbon filters use catalytic carbon — verify before purchasing.
What Municipal Water Users Usually Don’t Need
- UV disinfection: Your water is already disinfected. UV is unnecessary unless you have a specific concern about your distribution system.
- Sediment filtration: Municipal water is already filtered. Unless you have very old pipes that shed rust, a dedicated sediment filter is usually unnecessary.
- Iron/manganese filtration: These are treated at the municipal plant. If you’re seeing iron staining on city water, the issue is likely your own pipes, not the water supply.
Filtration for Well Water
Well water filtration is more complex because you’re starting from untreated water. Your filtration goals depend entirely on your water test results, but common needs include:
- Disinfection (bacteria and virus protection)
- Iron and manganese removal (staining, taste)
- Hardness reduction (scale, soap scum)
- Sediment removal (protecting plumbing and downstream filters)
- Specific contaminant removal (arsenic, nitrates, radon, fluoride — based on test results)
Recommended Systems for Well Water
Minimum setup (good water test results, minor issues only): A sediment filter plus a water softener handles the most common well water complaints — particles and hardness. Cost: $1,000-$3,000 installed.
Standard setup (iron, hardness, bacteria concerns): Sediment filter → iron/manganese filter → water softener → UV disinfection. This addresses the most common well water issues comprehensively. Cost: $3,000-$5,000 installed.
Comprehensive setup (multiple contaminants including arsenic, nitrates, or PFAS): The standard setup above plus an under-sink RO system for drinking water. The whole-house system handles aesthetic and infrastructure issues; the RO handles health contaminants at the kitchen tap. Cost: $3,500-$7,000 installed.
Critical first step: Get a comprehensive water test before buying anything. Well water varies enormously — your neighbor’s well might have completely different water quality than yours, even if you’re only a few hundred feet apart. A $200-$400 water test prevents thousands of dollars in wrong equipment purchases.
What Well Water Users Usually Don’t Need
- Chlorine removal: There’s no chlorine in well water (unless you’re adding it yourself via a chlorination system, in which case you’d add a carbon filter downstream).
- Disinfection byproduct removal: No chlorine means no disinfection byproducts.
- Fluoride removal: Unless your water test shows naturally occurring fluoride above 2 ppm, this isn’t a concern for most wells.
Cost Comparison
Well water treatment is generally more expensive than municipal water filtration because you’re building a treatment system from scratch rather than supplementing an already-treated supply:
The higher cost of well water treatment is offset by the absence of a monthly water bill. Municipal water customers pay $30-$70/month on average for water and sewer service. Over 10 years, that’s $3,600-$8,400 — which can exceed the total cost of well water treatment equipment and maintenance.
Testing: Different Approaches for Different Sources
Municipal Water Testing
Your utility does the testing for you. The annual CCR lists all detected contaminants and their levels. You can find your CCR on your utility’s website or through the EPA’s CCR search tool. If you want to verify what’s actually reaching your tap (which can differ from the utility’s testing points), a home water test from a company like Tap Score costs $100-$300 for a city water panel.
Well Water Testing
You’re responsible for all testing. The EPA recommends annual testing for bacteria and nitrates at minimum. A comprehensive initial test should cover bacteria, nitrates, pH, TDS, hardness, iron, manganese, arsenic, lead, and any contaminants of local concern. Retest annually for bacteria and nitrates, and do a comprehensive retest every 3-5 years or after any event that could affect water quality (flooding, well repair, nearby construction).
Switching Between Sources
If you’re moving from city water to well water (or vice versa), here’s what changes:
Moving from City Water to Well Water
- Get a comprehensive water test immediately — don’t assume the previous owner’s test results are still valid
- Your existing carbon filter won’t address well water’s primary concerns (bacteria, iron, hardness)
- Budget for a more complex treatment system
- Learn your well’s basics: depth, age, pump type, pressure tank size
- Establish an annual testing routine
Moving from Well Water to City Water
- Your well water treatment equipment (iron filter, softener, UV) is likely unnecessary and can be bypassed or removed
- You may still want a carbon filter for chlorine taste and a point-of-use filter for lead/PFAS
- Read your new utility’s CCR to understand what’s in the water
- Your filtration needs (and costs) will likely decrease significantly
Frequently Asked Questions
Is well water safer than city water?
Neither is inherently safer. Municipal water is regulated, tested, and treated — but it can contain disinfection byproducts, lead from aging infrastructure, and PFAS from industrial contamination. Well water avoids those treatment chemicals but can contain bacteria, arsenic, nitrates, and other naturally occurring contaminants. The safest water is whichever source has been properly tested and appropriately filtered for its specific contaminant profile.
Can I use a Brita pitcher on well water?
A Brita pitcher is designed for municipal water — it reduces chlorine taste and some contaminants but does not address the primary concerns of well water (bacteria, iron, hardness, nitrates, arsenic). Using a Brita on well water gives you a false sense of security. If you’re on well water, you need a treatment system designed for your specific water test results, not a pitcher filter designed for city water.
I’m on city water but my water tastes terrible. What’s the minimum I should do?
Start with a pitcher filter or faucet-mount filter — either one will dramatically improve chlorine taste for under $40. If you want better filtration (lead, PFAS, VOCs), step up to an under-sink carbon block filter certified to NSF 53. If you want the most thorough option, install an under-sink RO system. For whole-house chlorine removal (including showers), add a whole-house carbon filter.
My well water looks clear and tastes fine. Do I still need to test it?
Absolutely. Many of the most dangerous well water contaminants — arsenic, lead, nitrates, bacteria, radon — are colorless, odorless, and tasteless. You cannot detect them without a lab test. Clear, good-tasting water can still contain harmful levels of contaminants. Annual testing for bacteria and nitrates is the bare minimum for any private well.
Can I use the same filter system for both city and well water?
Some components overlap — an under-sink RO system works well on both sources, and a water softener addresses hardness regardless of source. But the overall system design is different. City water filtration focuses on removing treatment chemicals and distribution system contaminants. Well water treatment focuses on disinfection and removing naturally occurring contaminants. A system designed for one source won’t fully address the other’s needs.
The Bottom Line
Municipal water and well water require fundamentally different filtration approaches. City water users are supplementing an already-treated supply — a carbon filter or RO system handles most concerns. Well water users are building a complete treatment system from scratch, often requiring multiple stages to address sediment, iron, hardness, bacteria, and specific chemical contaminants. In both cases, the right approach starts with knowing what’s in your water: read your CCR if you’re on city water, or get a comprehensive lab test if you’re on a well.
Related articles:
- Well Water Treatment Guide — complete guide for private well owners
- How to Read a Water Quality Report — interpreting your CCR
- Best Water Filters for Well Water — top-rated well water systems
- Best Whole House Water Filters — whole-house options for both sources
- Water Filter Buying Guide — choosing the right filter type