| pH |
Chemical |
Measure of acidity/alkalinity |
pH units |
6.5 - 8.5 |
Disruption of aquatic life |
Industrial discharge, agricultural runoff |
| Total Dissolved Solids (TDS) |
Physical |
Total concentration of dissolved substances |
mg/L |
500 - 1000 |
Dehydration, kidney stones |
Urban runoff, wastewater discharge |
| Chemical Oxygen Demand (COD) |
Chemical |
Amount of oxygen required to oxidize organic matter |
mg/L |
0 - 200 |
Oxygen depletion in water bodies |
Municipal sewage, industrial waste |
| Biochemical Oxygen Demand (BOD) |
Chemical |
Amount of oxygen required by bacteria to decompose organic matter |
mg/L |
0 - 20 |
Oxygen depletion, fish kills |
Sewage, manure runoff |
| Nitrogen (Nitrate) |
Nutrient |
Concentration of nitrate ions in water |
mg/L |
0 - 10 |
Methemoglobinemia, algal blooms |
Fertilizers, septic systems |
| Phosphorus (Phosphate) |
Nutrient |
Concentration of phosphate ions in water |
mg/L |
0 - 0.1 |
Algal blooms, aquatic dead zones |
Fertilizers, detergents |
| Coliform Bacteria |
Microbial |
Presence of coliform bacteria as an indicator of fecal contamination |
CFU/100mL |
0 |
Gastrointestinal disease |
Sewage, wildlife waste |
| E.coli |
Microbial |
Presence of E. coli bacteria from fecal matter |
CFU/100mL |
0 |
Foodborne illness |
Sewage, storm runoff |
| Lead |
Heavy Metal |
Concentration of lead in water |
µg/L |
0 - 15 |
Neurological effects, developmental delays |
Corroded pipes, plumbing fixtures |
| Mercury |
Heavy Metal |
Concentration of mercury in water |
µg/L |
0 - 0.3 |
Neurological issues, kidneys |
Industrial discharge, mining |
| Arsenic |
Heavy Metal |
Concentration of arsenic in water |
µg/L |
0 - 10 |
Cancer, skin lesions |
Natural sources, industrial discharge |
| Fluoride |
Chemical |
Concentration of fluoride in water |
mg/L |
0.5 - 1.5 |
Dental fluorosis |
Water fluoridation, industrial runoff |
| Chlorine |
Chemical |
Concentration of chlorine used for disinfection |
mg/L |
0.2 - 4 |
Respiratory issues |
Water treatment facilities |
| Amonia (NH3) |
Nutrient |
Presence of ammonia in water |
mg/L |
0 - 0.5 |
Toxicity to aquatic life |
Agricultural runoff, sewage |
| Total Coliforms |
Microbial |
Total count of coliform bacteria as water quality indicator |
CFU/100mL |
0 |
Indicates fecal contamination |
Septic systems, animal waste |
| Turbidity |
Physical |
Clarity of water |
NTU |
0 - 5 |
Reduced light penetration, photosynthesis |
Soil erosion, algal blooms |
| Color |
Physical |
Color of water due to organic compounds or sediments |
Pt-Co units |
0 - 15 |
Aesthetic issues, may indicate contamination |
Industrial waste, natural runoff |
| Temperature |
Physical |
Temperature of water |
°C |
0 - 30 |
Influences oxygen solubility, affects aquatic life |
Seasonal changes, thermal pollution |
| Dissolved Oxygen (DO) |
Chemical |
Concentration of oxygen available to aquatic organisms |
mg/L |
5 - 14 |
Vital for aquatic life; low levels cause die-off |
Organic decomposition, eutrophication |
| Hardness |
Chemical |
Concentration of calcium and magnesium ions |
mg/L CaCO3 |
0 - 300 |
Scaling, can affect plumbing |
Natural sources, runoff |
| Hydrogen Sulfide (H2S) |
Chemical |
Presence of hydrogen sulfide gas |
mg/L |
0 - 0.05 |
Toxicity, bad odor |
Anaerobic decomposition, industrial discharge |
| Sulfate |
Chemical |
Concentration of sulfate in water |
mg/L |
250 - 500 |
Taste, laxative effects |
Industrial waste, natural sources |
| Chloride |
Chemical |
Concentration of chloride in water |
mg/L |
250 - 500 |
Taste, corrosion |
Salt runoff, industrial discharge |
| Conductivity |
Physical |
Ability of water to conduct electricity |
µS/cm |
<1500 |
High salinity, impacts aquatic life |
Urban runoff, leachate |
| Alkalinity |
Chemical |
Ability of water to resist pH changes |
mg/L CaCO3 |
20 - 200 |
Buffering capacity, affects aquatic environments |
Natural sources, pollution |
| Fecal Coliforms |
Microbial |
Specific indicator for fecal contamination |
CFU/100mL |
0 |
Gastrointestinal diseases |
Sewage, animal waste |
| Secchi Depth |
Physical |
Depth at which a Secchi disk is visible |
m |
0.5 - 3.0 |
Indication of water clarity |
Algal blooms, turbidity |
| Total Organic Carbon (TOC) |
Chemical |
Total concentration of organic compounds in water |
mg/L |
0 - 5 |
Indicates organic pollution |
Sewage, runoff |
| Zooplankton Diversity |
Biological |
Diversity of zooplankton species in water bodies |
Index |
Varies by ecosystem |
Indicates ecological health |
Eutrophication, pollution |
| Phytoplankton Density |
Biological |
Density of phytoplankton species in water bodies |
cells/mL |
Varies |
Indicates nutrient status |
Eutrophication, runoff |
| Macroinvertebrate Diversity |
Biological |
Diversity of macroinvertebrates in habitats |
Index |
Varies by ecosystem |
Indicates water quality |
Sedimentation, pollution |
| Salinity |
Physical |
Salt concentration in water |
ppt |
0 - 35 |
Affects osmotic balance in aquatic organisms |
Urban runoff, desalination effluents |
| Toxicity (LC50) |
Chemical |
Concentration of substances that is lethal to 50% of test organisms |
mg/L |
Depends on species |
Ecotoxicity, biodiversity loss |
Industrial chemicals, agricultural runoff |
| Volatile Organic Compounds (VOCs) |
Chemical |
Concentration of organic chemicals that evaporate easily |
µg/L |
0 - 500 |
Health risks, taste issues |
Industrial solvents, leaks |
| Endocrine Disruptors |
Chemical |
Chemicals affecting hormonal systems |
µg/L |
0 - 0.1 |
Reproductive issues, developmental problems |
Agricultural runoff, industrial discharge |
| Microcystin |
Chemical |
Toxin produced by cyanobacteria in water |
µg/L |
0 - 1 |
Liver damage, gastrointestinal illnesses |
Cyanobacterial blooms, nutrient runoff |
| Arsenic (Inorganic) |
Chemical |
Presence of inorganic arsenic in water |
µg/L |
0 - 10 |
Cancer, skin lesions |
Mining, agricultural runoff |
| 2,4-D |
Chemical |
Concentration of herbicide 2,4-D |
µg/L |
0 - 70 |
Potential health effects, environmental toxicity |
Agricultural runoff |
| Glyphosate |
Chemical |
Concentration of herbicide glyphosate |
µg/L |
0 - 0.1 |
Cancer risk, ecological impacts |
Agricultural runoff |
| Atrazine |
Chemical |
Concentration of herbicide atrazine |
µg/L |
0 - 3 |
Hormonal effects, aquatic life impacts |
Agricultural runoff |
| Phenols |
Chemical |
Presence of phenolic compounds in water |
µg/L |
0 - 1 |
Health risks, taste issues |
Industrial waste, wastewater |
| Petroleum Hydrocarbons |
Chemical |
Concentration of oil and petroleum products in water |
mg/L |
0 - 0.1 |
Toxicity to aquatic life |
Oil spills, urban runoff |
| Organophosphates |
Chemical |
Concentration of pesticides |
µg/L |
0 - 0.1 |
Health risks, aquatic toxicity |
Agricultural runoff |
| Colorimetric Indicators |
Chemical |
Various colorimetric tests for water quality measurements |
Varies |
Varies |
Depends on the chemical |
Varies by source |
| Insecticide Residues |
Chemical |
Presence of insecticides in water samples |
µg/L |
0 - 0.01 |
Health risks, toxicity |
Agricultural runoff |
| Waterborne Pathogens |
Microbial |
Presence of pathogens in water affecting health |
CFU/100mL |
0 |
Infectious diseases |
Sewage, untreated water |
| Oil and Grease |
Chemical |
Presence of oil and grease in water |
mg/L |
0 - 5 |
Taste and aesthetic issues |
Urban runoff, industrial discharge |
| Plastic Particles |
Physical |
Presence of microplastics in water |
particles/L |
0 - 10 |
Ecological impacts, ingestion by aquatic life |
Plastic pollution |
| Salmonella |
Microbial |
Presence of Salmonella bacteria |
CFU/100mL |
0 |
Foodborne illnesses |
Sewage, contaminated water |
| Nitrite |
Nutrient |
Concentration of nitrite ions in water |
mg/L |
0 - 1 |
Methemoglobinemia |
Fertilizers, industrial processes |
| Strontium |
Heavy Metal |
Concentration of strontium in water |
mg/L |
0 - 4 |
Bone health, toxic effects |
Natural sources, industrial discharge |
| Cadmium |
Heavy Metal |
Concentration of cadmium in water |
µg/L |
0 - 5 |
Kidney damage, bone fragility |
Mining, industrial effluents |
| Internal Corrosion Rates |
Chemical |
Rate of corrosion in pipes/structures |
mm/year |
0 |
System integrity, safety |
pH levels, water chemistry |
| Selenium |
Heavy Metal |
Concentration of selenium in water |
µg/L |
0 - 50 |
Toxicity, reproductive issues |
Natural sources, mining |
| Tritium |
Radiological |
Presence of radioactive hydrogen isotope |
Bq/L |
0 - 0.1 |
Cancer risk |
Nuclear waste, natural sources |
| Uranium |
Radiological |
Concentration of uranium in water |
µg/L |
0 - 30 |
Kidney toxicity, cancer risk |
Mining, natural sources |
| Radon |
Radiological |
Radon concentration in water |
pCi/L |
<300 |
Lung cancer risk |
Natural decay of uranium |
| Methane |
Chemical |
Presence of methane in water |
mg/L |
0 - 0.1 |
Contributes to climate change |
Anaerobic decomposition |
| Iron |
Chemical |
Concentration of iron in water |
mg/L |
0 - 0.3 |
Taste issues, staining |
Natural sources, mining |
| Zinc |
Heavy Metal |
Concentration of zinc in water |
mg/L |
0 - 5 |
Taste issues, skin irritation |
Natural sources, industrial discharge |
| Chromium |
Heavy Metal |
Concentration of chromium in water |
µg/L |
0 - 50 |
Carcinogenic effects, allergic reactions |
Industrial discharge, leaching |
| Brominated Compounds |
Chemical |
Presence of brominated organic compounds |
µg/L |
0 - 0.5 |
Health risks |
Water treatment byproducts |
| Napthalene |
Chemical |
Presence of naphthalene in water |
µg/L |
0 - 0.1 |
Health risks, taste issues |
Industrial discharges, polycyclic aromatic hydrocarbons |
| Talcum Powder |
Chemical |
Detection of talcum powder in water |
mg/L |
0 - 1 |
Health effects, contamination indicator |
Industrial runoff |
| Conductivity (specific) |
Physical |
Specific conductivity measuring ionic presence |
µS/cm |
Varies |
Water quality indication |
Salinity, mineral content |
| TSS (Total Suspended Solids) |
Physical |
Total amount of suspended solids in water |
mg/L |
0 - 30 |
Ecological impacts, water clarity |
Erosion, runoff |
| Pesticide Residues |
Chemical |
Presence of pesticide residues in water samples |
µg/L |
0 - 0.1 |
Health risks, aquatic toxicity |
Agricultural runoff |
| Herbicide Residues |
Chemical |
Presence of herbicide residues |
µg/L |
0 - 0.1 |
Health risks, ecological effects |
Agricultural runoff |
| Antimony |
Heavy Metal |
Concentration of antimony in water |
µg/L |
0 - 6 |
Health risks, toxic effects |
Industrial discharge |
| Barium |
Heavy Metal |
Concentration of barium in water |
µg/L |
0 - 1000 |
Hypertension, toxic effects |
Natural sources, industrial discharge |
| Softness |
Chemical |
Presence of soft water characteristics |
mg/L CaCO3 |
0 - 150 |
Corrosive potential |
Natural sources |
| Lactic Acid Bacteria |
Microbial |
Presence of beneficial lactic acid bacteria in water |
CFU/mL |
Varies |
Indicates positive ecological health |
Natural processes |
| Enterococci |
Microbial |
Presence of Enterococci bacteria in water |
CFU/100mL |
0 |
Indicates fecal contamination |
Sewage, animal waste |
| Heavy Metals (Total) |
Heavy Metal |
Total concentration of heavy metals in water |
µg/L |
Varies |
Health risks, environmental toxicity |
Industrial discharge, sewage |
| Volatile Fatty Acids (VFA) |
Chemical |
Presence of VFAs in water |
mg/L |
0 - 100 |
Indicates anaerobic activity |
Organic matter decomposition |
| Non-Methane Hydrocarbons |
Chemical |
Presence of non-methane hydrocarbons in water |
µg/L |
0 - 10 |
Health risks, environmental concerns |
Urban runoff, industrial processes |
| Organic Phosphate Compounds |
Chemical |
Concentration of organic phosphates in water |
µg/L |
0 - 0.1 |
Eutrophication risk |
Agricultural runoff |
| Hydrocarbon Degradation Products |
Chemical |
Products from the breakdown of hydrocarbons |
mg/L |
0 - 1 |
Indicate pollution level |
Oil spills, industrial processes |
| Chromium (VI) |
Heavy Metal |
Concentration of hexavalent chromium in water |
µg/L |
0 - 10 |
Cancer, skin effects |
Industrial discharge, corrosion |
| Potassium |
Nutrient |
Concentration of potassium in water |
mg/L |
0 - 10 |
Essential for aquatic plants |
Natural sources, fertilizers |
| Carbon Dioxide (CO2) |
Chemical |
Presence of carbon dioxide in water |
mg/L |
0 - 50 |
Acidification risks |
Aquatic respiration, organic decomposition |
| Acetone |
Chemical |
Presence of acetone in water |
µg/L |
0 - 100 |
Health risks, taste issues |
Industrial discharge, solvents |
| Trace Elements |
Heavy Metal |
Concentration of various trace elements in water |
µg/L |
Varies |
Health risks, environmental contamination |
Industrial processes, natural sources |
| Oxidation-Reduction Potential (ORP) |
Chemical |
Measurement of water's ability to oxidize or reduce substances |
mV |
Varies |
Indicates chemical activity |
Organic matter, pollutants |
| Polyaromatic Hydrocarbons (PAHs) |
Chemical |
Presence of PAHs in water |
µg/L |
0 - 0.1 |
Carcinogenic effects |
Oil spills, urban runoff |
| Cyanide |
Chemical |
Presence of cyanide in water |
µg/L |
0 - 0.2 |
Toxicity, health risks |
Industrial discharge, mining |
| Detergents |
Chemical |
Concentration of detergents in water |
mg/L |
0 - 0.5 |
Health risks, ecological effects |
Urban runoff, wastewater |
| Thermal Pollution |
Physical |
Effect of heated water on aquatic environments |
°C |
Varies |
Thermal stress on organisms |
Industrial processes, power plants |
| Surface Tension |
Physical |
Measure of liquid's surface tension |
mN/m |
Varies |
Indicates surfactants presence |
Pollution, organic compounds |
| Biotic Indices |
Biological |
Indicator based on living organisms in a habitat |
Index |
Varies |
Indicates environmental quality |
Pollution, habitat health |
| Ammonification Rate |
Chemical |
Rate at which organic nitrogen is converted to ammonia |
mg/L/day |
Varies |
Indicates decomposition rate |
Organic matter processes |
| Seasonal Variation Index |
Biological |
Measure of seasonal changes in ecology |
Index |
Varies |
Indicates environmental stability |
Climate factors |
| UV Absorbance |
Chemical |
Absorbance at UV wavelengths as an indicator of organic content |
cm-1 |
0 - 0.1 |
Indicates organic pollution |
Wastewater, natural sources |
| Eutrophication Index |
Chemical |
Measure of nutrient enrichment and algal growth potential |
Index |
0 - 1 |
Indicates risk of eutrophication |
Nitrogen and phosphorus inputs |
| Water Quality Index (WQI) |
Composite |
Composite score based on multiple indicators |
Index |
0 - 100 |
Indicates overall water quality |
Aggregated parameters |
| Sediment Quality Triad |
Composite |
Assessment based on sediment, chemistry and biology |
Index |
Varies |
Indicates sediment quality |
Sediment analysis |
| Bioassessment Metrics |
Biological |
Metric based on organism assessments |
Index |
Varies |
Indicates ecological health |
Sampling protocols |
| Water Smell |
Physical |
Odor characteristics of water |
Type |
Varies |
Indicates pollution or natural conditions |
Sewage, organic decomposition |
| Surface Water Temperature |
Physical |
Measuring temperature at water surface |
°C |
0 - 30 |
Affects aquatic life |
Seasonal changes, climate |
| Subsurface Temperature |
Physical |
Measuring temperature below water surface |
°C |
0 - 30 |
Affects habitat suitability |
Seasonal variations |
| Bottom Sediment Quality |
Physical |
Quality assessment of bottom sediments |
Index |
Varies |
Indicates pollution levels |
Depositional environment |
| Water Color Change |
Physical |
Visible changes in water color |
Pt-Co units |
Varies |
Aesthetic and pollution indicators |
Algal impacts, organic matter |
| Ecological Footprint (Water) |
Composite |
Measurement of water use impact on environment |
L |
Varies |
Indicates sustainability |
Consumption patterns |
| Phytoplankton Diversity Index |
Biological |
Index measuring diversity of phytoplankton |
Varies |
Varies |
Indicates nutrient levels |
Eutrophication risk |
| Chemicals of Emerging Concern |
Chemical |
Presence of emerging contaminants |
µg/L |
0 - 1 |
Health and environmental risks |
Pollutants entering waterways |
| Fish Community Composition |
Biological |
Assessment of fish species in an area |
Index |
Varies |
Indicates habitat quality |
Fishing pressure, pollution |
| Biological Oxygen Demand (BOD5) |
Chemical |
Water's biochemical activity measure over 5 days |
mg/L |
0 - 20 |
Oxygen consumption, waste presence |
Sewage, runoffs |
| Manganese |
Heavy Metal |
Concentration of manganese in water |
µg/L |
0 - 50 |
Neurological issues, taste |
Natural sources, mining |
| Trihalomethanes (THMs) |
Chemical |
Presence of disinfection byproducts |
µg/L |
0 - 80 |
Cancer risk, liver damage |
Water chlorination processes |
| Water Supply Sustainability Index |
Composite |
Measurement of sustainability of water sources |
Index |
Varies |
Indicates long-term viability |
Water management practices |
| Irrigation Return Flow Quality |
Chemical |
Quality assessment of irrigation return flows |
Varies |
Varies |
Health of receiving waters |
Agricultural practices |
| Carbonate Hardness |
Chemical |
Presence of carbonate minerals contributing to hardness |
mg/L CaCO3 |
0 - 300 |
Water quality parameters |
Natural geology |
| Trace Organic Contaminants |
Chemical |
Presence of organic pollutants |
µg/L |
0 - 1 |
Environmental and health risks |
Industrial and agricultural runoff |
| Micromollusks Presence |
Biological |
Presence of micromollusks as bioindicators |
Count |
Varies |
Indicates habitat health |
Ecosystem health assessments |
| Metals Mobility Index |
Chemical |
Measure of heavy metal mobility in water |
Index |
Varies |
Indicates toxicity risk |
Soil and sediment interaction |
| Terrestrial Runoff Impact Score |
Composite |
Assessment of runoff impact on water body |
Index |
Varies |
Indicates pollutant delivery |
Land use practices |
| Gaseous Emissions (from water) |
Chemical |
Emissions of gases from water bodies |
Varies |
Varies |
Indicates biological and chemical processes |
Decomposition rates |