Water Quality by Source: Surface Water vs Groundwater
Your water source matters. Whether your city gets water from rivers and lakes or from underground aquifers affects what contaminants you might find and how the water is treated. Learn about different water sources and browse cities by their source type.
Understanding Water Source Types
Surface Water
Water sourced from rivers, lakes, and reservoirs
Advantages
- Abundant supply in most regions
- Easier to access and treat
- Lower mineral content
- Natural flow helps prevent stagnation
Challenges
- More susceptible to pollution runoff
- Higher turbidity and biological contamination
- Seasonal variations in quality
- Requires more extensive treatment
Groundwater (Aquifers & Wells)
Water sourced from underground aquifers accessed via wells
Advantages
- Naturally filtered through soil and rock
- Protected from surface contamination
- More consistent quality year-round
- Lower treatment requirements
Challenges
- Can contain high mineral content (hard water)
- Slower to replenish if overused
- May have naturally occurring contaminants like arsenic
- Vulnerable to industrial contamination
Mixed Sources
Water from combination of surface and groundwater sources
Advantages
- Supply diversification reduces risk
- Can balance seasonal variations
- Flexibility in water management
- Backup sources available
Challenges
- More complex treatment requirements
- Varying water quality characteristics
- Higher infrastructure costs
- Complex monitoring needs
Common Contaminants by Water Source
Typical in Surface Water
- Microorganisms: Bacteria, viruses, parasites from agricultural runoff
- Nitrates: From fertilizer and agricultural runoff
- Disinfection Byproducts: TTHMs and HAAs from chlorine treatment
- Sediment & Turbidity: Particles affecting water clarity
Typical in Groundwater
- Arsenic: Naturally occurring from rock formations
- Radium & Uranium: Natural radioactive elements
- Minerals: Calcium, magnesium causing hard water
- PFAS: From industrial contamination seeping into aquifers
Browse Cities by Water Quality
Click any city to see their water source type and detailed quality report
Highest Water Quality Cities
Payson
Arizona
98
A+
Anaheim
California
98
A+
Romeoville
Illinois
98
A+
Cumberland
Maryland
98
A+
Pine Bluff
Arkansas
97
A+
Palm Desert
California
97
A+
San Clemente
California
97
A+
West Haven
Connecticut
97
A+
Naperville
Illinois
97
A+
Greenwood
Indiana
97
A+
Salina
Kansas
97
A+
Radcliff
Kentucky
97
A+
El Paso
Texas
97
A+
Prichard
Alabama
96
A+
Hanford
California
96
A+
Average Water Quality Cities
Dodge City
Kansas
84
B+
Olathe
Kansas
84
B+
Louisville
Kentucky
84
B+
Winchester
Kentucky
84
B+
New Iberia
Louisiana
84
B+
Arlington
Massachusetts
84
B+
Barnstable Town
Massachusetts
84
B+
Natick
Massachusetts
84
B+
Waltham
Massachusetts
84
B+
Baltimore
Maryland
84
B+
Bowie
Maryland
84
B+
Carney
Maryland
84
B+
Easton
Maryland
84
B+
Essex
Maryland
84
B+
Auburn
Maine
84
B+
Cities with Water Quality Concerns
Cape Coral
Florida
48
F
Plantation
Florida
48
F
Dalton
Georgia
48
F
Lenexa
Kansas
48
F
Indio
California
47
F
San Jose
California
47
F
Safety Harbor
Florida
47
F
Hanover Park
Illinois
47
F
Mishawaka
Indiana
46
F
Bardstown
Kentucky
46
F
San Bernardino
California
45
F
San Marcos
California
45
F
Windsor
Colorado
45
F
Alameda
California
44
F
Union City
Georgia
44
F
Choosing Filters for Your Water Source
The right water filter depends on both your water source and the specific contaminants detected:
For Surface Water Cities
- Activated carbon for chlorine taste and disinfection byproducts
- Sediment filters for turbidity and particles
- UV filters for additional microorganism protection
- Consider whole-house systems for comprehensive treatment
For Groundwater Cities
- Reverse osmosis for arsenic, radium, and heavy metals
- Water softeners for hard water minerals
- Activated carbon certified for PFAS if present
- Ion exchange for specific metal removal