Is Seneca, KS Tap Water Safe to Drink?
Graded B — but Copper was detected above EPA limits. Here's what's in the water and how to remove it. What to do next ↓
78.8/100
waterverge.com Seneca, KS — Water Quality Report
Seneca's drinking water received a grade of B (78.8 out of 100), indicating good water quality. The city's 2 water systems serve approximately 4,930 residents using groundwater.
Lead levels were measured at 3.6 ppb (90th percentile), well within EPA limits. This system has not yet been tested for PFAS under the EPA UCMR 5 program.
The system has 10 violations on record, including 3 health-based violations. 8 remain unresolved.
What to know about Seneca's water
Seneca ranks #180 out of 323 cities in Kansas for water quality, placing it below average in the state.
Seneca relies on groundwater, which is generally less vulnerable to surface contamination but can be affected by naturally occurring minerals like arsenic and nitrate, as well as agricultural and industrial runoff.
Water quality score
See methodology →Is Seneca, KS water safe to drink?
Seneca's drinking water has significant quality concerns based on EPA testing data. With a grade of B (78.8/100), the system has issues across multiple categories. A water filter is recommended for all residents. The city's 2 water systems serve approximately 4,930 residents using groundwater (wells).
Recent water quality updates for Seneca
A timeline of significant water quality events, violations, and data updates.
Latest EPA compliance and testing data incorporated into Seneca's water quality assessment. Grade: B (78.8/100).
Contaminants: Consumer Confidence Rule.
Contaminants: Lead and Copper Rule.
Federal disaster declaration (FEMA DR-3236). Hurricane event — may have impacted local water infrastructure.
1 health-based. Contaminants: Lead and Copper Rule.
Federal disaster declaration (FEMA DR-1000). Flood event — may have impacted local water infrastructure.
Key contaminant findings
Based on the most recent EPA sampling data for Seneca's water supply.
Well within EPA limits.
Exceeds EPA action level. Copper can leach from household plumbing — flush taps for 30 seconds before drinking.
Violation history
Seneca's water system has 10 total violations on record, including 3 health-based violations. 8 remain unresolved.
Flood & environmental risk
Nemaha County has experienced 4 federally declared disasters since 1973. Flooding and severe storms can overwhelm water treatment plants, cause sewage overflows, and introduce agricultural runoff, bacteria, and sediment into drinking water supplies. Local water sources include Turkey C Nr Seneca.
Where does Seneca's water come from?
Seneca's drinking water comes from groundwater (wells), supplied by 2 water systems serving approximately 4,930 people. Groundwater is generally less susceptible to surface contamination but can contain naturally occurring contaminants like arsenic, radon, and nitrate. Nearby water bodies include Turkey C Nr Seneca (river).
What Seneca residents can do
Recommended: NSF-certified water filter. This addresses the specific contaminants found in Seneca's water.
Your water utility is required to publish an annual Consumer Confidence Report (CCR) with detailed testing results. Ask for the latest copy or check your utility's website.
Run cold water for 30 seconds before drinking, especially in the morning. Lead and copper leach from household plumbing when water sits in pipes.
Seneca's area has a history of flooding. After severe weather, watch for boil water advisories from your local utility.
Data: EPA SDWIS, UCMR 5 (PFAS), FEMA, NOAA. Last updated May 2026.
Top contaminants to know
View all ↓Violation summary
Violations & advisories
Flood & disaster history
Nemaha County has experienced 4 federally declared disasters since 1973. Flooding and severe weather can compromise water treatment infrastructure and introduce contaminants into drinking water supplies.
Recommended water filters
Based on contaminants detected in Seneca's water supply, we recommend the following filter types.
Full contaminants report
| Contaminant | Detected Level | EPA Limit | Unit | Category | Status |
|---|---|---|---|---|---|
| Lead (90th percentile) LeadHeavy Metal A toxic heavy metal that can leach into drinking water from older pipes, solder, and fixtures. No amount of lead in water is considered safe. Health EffectsBrain and nervous system damage in children, kidney damage, high blood pressure, and reproductive problems in adults. EPA Limit15 ppb action level Common SourcesCorrosion of lead pipes, lead solder, brass faucets, and household plumbing. | 3.6 | 15 | ppb | Inorganic | Safe |
| Copper (90th percentile) CopperInorganic A metal that enters drinking water mainly through corrosion of copper plumbing. Small amounts are essential for health, but excess levels are harmful. Health EffectsGastrointestinal distress (nausea, vomiting, diarrhea) at short-term high levels; liver and kidney damage from long-term exposure. EPA Limit1.3 mg/L action level Common SourcesCorrosion of copper household plumbing, erosion of natural deposits. | 2.00 | 1.3 | mg/L | Inorganic | Over Limit |
Lead level trend (90th percentile)
Copper level trend (90th percentile)
See how Seneca compares by contaminant
Explore where Seneca ranks among all Kansas cities for specific contaminants.
Water source & infrastructure
Where Seneca's water comes from
Seneca's drinking water is drawn from underground aquifers through wells.
Groundwater is naturally filtered through rock and soil layers, generally requiring less treatment than surface water. However, it can contain naturally occurring contaminants like arsenic, radon, and minerals.
Agricultural activity, septic systems, and industrial operations near well fields can introduce nitrates, pesticides, and volatile organic compounds.
The system is operated by local government ownership and serves approximately 4,930 people through 2 water systems.
Water bodies near Seneca
Seneca is located near 1 notable water body. These water bodies contribute to the regional watershed and may indirectly affect groundwater quality.
Water systems serving Seneca
| System Name | PWSID | Population | Source |
|---|---|---|---|
| NEMAHA CO RWD 3 | KS2013110 | 2,800 | GW |
| SENECA, CITY OF | KS2013102 | 2,130 | SW |
How Seneca compares
Full Kansas rankings →Seneca's score of 78.8/100 is above the average of 62/100 among major Kansas cities. It outscores 7 of 10 nearby cities.
Nearby cities
View Kansas rankings →About Seneca, KS
Wikipedia →Seneca is a city in and the county seat of Nemaha County, Kansas, United States. As of the 2020 census, the population of the city was 2,139.
Learn more about your water
Guides and resources related to Seneca's water quality findings.
Explore water quality across Nemaha
Frequently asked questions
Is Seneca, KS tap water safe to drink?
Seneca's water quality earned a grade of B (78.8/100). Some concerns have been identified. Consider a water filter for an extra layer of protection. The city ranks #180 out of 323 cities tested in Kansas.
What contaminants are in Seneca's water?
Lead was measured at 3.6 ppb (90th percentile). 10 violations are on record.
How is Seneca's water quality grade calculated?
The grade is based on four factors: violation history (40%), lead and copper levels (25%), PFAS contamination (25%), and regulatory compliance (10%). The score is also adjusted based on how complete the available data is. See our methodology page for full details.
Do I need a water filter in Seneca?
Based on current data, basic filtration should suffice for additional peace of mind.
Where does Seneca's water come from?
Seneca's water is sourced from Groundwater. The city has 2 water systems serving approximately 4,930 residents.
What health violations has Seneca's water system had?
Seneca has 3 health-based violations on record. The most recent violation was recorded in July 2019. Health-based violations mean the water exceeded EPA maximum contaminant levels (MCLs) for a regulated substance. 8 violations remain unresolved.
Is Seneca's groundwater at risk of contamination?
Seneca uses groundwater, which can be affected by naturally occurring contaminants like arsenic, radon, and nitrate, as well as agricultural runoff and industrial activity. The system has 10 violations on record that may relate to groundwater quality. Groundwater systems are generally less susceptible to surface contamination but should be monitored for emerging contaminants like PFAS.
How does Seneca's water compare to other cities?
Seneca ranks #180 out of 323 cities in Kansas (better than 44% of state cities) and #8510 out of 15744 cities nationally (46th percentile). The grade of B reflects the combined assessment of violation history, lead and copper levels, PFAS contamination, and regulatory compliance.