Understanding Contaminants in Water Quality Reports

Microbiological Contaminants

Total Coliform Bacteria

• What it is: Indicator of potential contamination

• Health significance: Not usually harmful itself, but indicates other germs might be present

• MCL: No more than 5% of monthly samples can be positive

• Red flags: Any positive samples, especially recurring positives

• Sources: Sewage, animal waste, soil

E. coli

• What it is: Specific type of coliform from human/animal intestines

• Health significance: Immediate health risk - can cause severe illness

• MCL: Zero tolerance - any detection triggers immediate action

• Red flags: ANY detection is serious

• Sources: Human/animal fecal contamination

Giardia and Cryptosporidium

• What they are: Parasites causing gastrointestinal illness

• Health significance: Cause severe diarrhea, especially dangerous for immunocompromised

• Monitoring: Not all systems test; treatment technique required instead

• Red flags: Any detection in treated water

• Sources: Animal waste, sewage overflow

Chemical Contaminants - Health-Based

Lead

• What it is: Toxic metal that accumulates in body

• Health significance: Damages nervous system, especially harmful to children

• Action Level: 15 ppb (90th percentile of home samples)

• Red flags: Any level above 15 ppb, or increasing trends

• Sources: Lead pipes, fixtures, solder in homes built before 1986

Copper

• What it is: Essential nutrient that becomes toxic at high levels

• Health significance: Gastrointestinal distress, liver/kidney damage

• Action Level: 1.3 ppm (90th percentile)

• Red flags: Levels above 1.3 ppm, blue-green staining

• Sources: Copper plumbing, corrosion

Nitrates/Nitrites

• What they are: Nitrogen compounds

• Health significance: "Blue baby syndrome" in infants under 6 months

• MCL: Nitrate = 10 ppm, Nitrite = 1 ppm

• Red flags: Any level above MCL, especially for families with infants

• Sources: Fertilizer, septic systems, animal waste

Arsenic

• What it is: Naturally occurring toxic element

• Health significance: Cancer, skin damage, circulatory problems

• MCL: 10 ppb

• Red flags: Any detection, especially levels above 5 ppb

• Sources: Natural deposits, mining, industrial waste

PFAS (Per- and polyfluoroalkyl substances)

• What they are: "Forever chemicals" used in non-stick products

• Health significance: Cancer, liver damage, immune system effects

• Regulation: New EPA limits being implemented

• Red flags: Any detection (extremely persistent in environment)

• Sources: Industrial processes, firefighting foam, consumer products

Disinfection and Disinfection Byproducts

Chlorine/Chloramines

• What they are: Added to kill germs

• Health significance: Generally safe but can cause taste/odor issues

• MRDL: Chlorine = 4 ppm, Chloramines = 4 ppm

• Red flags: Levels consistently at maximum, strong taste/odor

• Purpose: Required for disinfection

Total Trihalomethanes (TTHMs)

• What they are: Byproducts formed when chlorine reacts with organic matter

• Health significance: Potential cancer risk with long-term exposure

• MCL: 80 ppb (running annual average)

• Red flags: Levels above 60 ppb, increasing summer levels

• Sources: Chlorination of water with organic material

Haloacetic Acids (HAA5)

• What they are: Another group of disinfection byproducts

• Health significance: Potential cancer risk, reproductive effects

• MCL: 60 ppb (running annual average)

• Red flags: Levels above 45 ppb, upward trends

• Sources: Similar to TTHMs

Radioactive Contaminants

Gross Alpha

• What it is: Screening test for alpha radiation

• Health significance: Cancer risk

• MCL: 15 pCi/L

• Red flags: Levels above 10 pCi/L

• Sources: Natural uranium deposits

Radium 226 + 228

• What they are: Specific radioactive elements

• Health significance: Bone cancer, other cancers

• MCL: 5 pCi/L (combined)

• Red flags: Any detection above 3 pCi/L

• Sources: Natural deposits

Radon

• What it is: Radioactive gas that dissolves in water

• Health significance: Lung cancer when released into air

• Status: Proposed MCL of 300 pCi/L

• Red flags: Levels above 1,000 pCi/L

• Sources: Natural decay of uranium in rock

Secondary Standards (Aesthetic)

Iron

• What it is: Common mineral

• Effects: Metallic taste, reddish-brown staining

• SMCL: 0.3 ppm

• Health significance: Not harmful at typical levels

• Sources: Natural deposits, corroding pipes

Manganese

• What it is: Essential nutrient, aesthetic nuisance at higher levels

• Effects: Metallic taste, black staining

• SMCL: 0.05 ppm

• Health significance: Neurological effects at very high levels

• Sources: Natural deposits

Sulfate

• What it is: Naturally occurring mineral

• Effects: Bitter taste, laxative effect

• SMCL: 250 ppm

• Health significance: Diarrhea in sensitive individuals

• Sources: Natural deposits

Total Dissolved Solids (TDS)

• What it is: All dissolved minerals combined

• Effects: Taste, hardness, scaling

• SMCL: 500 ppm

• Health significance: Not harmful

• Sources: Natural mineral content

Emerging Contaminants to Watch

Pharmaceutical Compounds

• Status: Not regulated but increasingly detected

• Sources: Human/animal medications, improper disposal

• Concerns: Unknown long-term effects, antibiotic resistance

Microplastics

• Status: Research ongoing, no regulations yet

• Sources: Plastic breakdown, synthetic textiles, tire wear

• Concerns: Physical effects, chemical transport

Cyanotoxins

• Status: Some regulations under development

• Sources: Blue-green algae blooms

• Concerns: Liver damage, neurological effects

Interpreting Your Results

Low-Risk Situations

• All contaminants well below MCLs

• Consistent results year to year

• No increasing trends

• Good source water protection

Monitor Closely

• Any contaminant above 50% of MCL

• Increasing trends over multiple years

• Seasonal variations in disinfection byproducts

• Lead/copper approaching action levels

Take Action

• Any MCL violations

• E. coli detections

• Lead above 15 ppb in your home

• Multiple violations or enforcement actions

Health Effects Summary

Immediate Health Risks

• E. coli: Severe diarrhea, kidney failure

• High nitrates: Blue baby syndrome

• Very high copper: Gastrointestinal illness

Long-term Health Risks

• Lead: Developmental delays, learning disabilities

• Arsenic: Cancer, cardiovascular disease

• PFAS: Cancer, immune system effects

• Disinfection byproducts: Cancer risk

Vulnerable Populations

• Infants: Lead, nitrates, bacteria

• Pregnant women: Lead, disinfection byproducts

• Immunocompromised: All microbial contaminants

• Elderly: Bacteria, chemical contaminants

When to Consider Home Treatment

Specific Contaminant Issues

• Lead levels above Action Level

• High levels of aesthetic contaminants (iron, sulfate)

• Disinfection byproduct concerns

• Private well contamination

Treatment Options by Contaminant

• Lead: Certified lead-reducing filters

• Bacteria: UV disinfection, boiling

• Nitrates: Reverse osmosis, distillation

• Arsenic: Specialized arsenic removal systems

• PFAS: Activated carbon, reverse osmosis

Questions to Ask Your Water Utility

About Test Results

• "What does this level mean for my health?"

• "How does this compare to previous years?"

• "What is the source of this contamination?"

• "What treatment removes this contaminant?"

About Future Plans

• "Are you planning system improvements?"

• "How will you address increasing levels?"

• "What source water protection measures are in place?"

• "When will the next round of testing occur?"