Andrew Schry, president of the Culligan Water team in Cranberry Township, Pennsylvania, frequently helps clients understand the factors that define water quality. Water quality is determined by a combination of physical, chemical, and biological characteristics that influence safety, taste, and suitability for use—whether the source is a private well, municipal system, or a freshwater stream encountered while camping.
One important factor is temperature. In natural ecosystems, water temperature affects density, biological activity, and dissolved oxygen levels. As temperature increases, the solubility of gases—such as oxygen—decreases, which can stress aquatic life. Warmer water also accelerates plant growth and can contribute to algae blooms. When algae die and decompose, oxygen levels may drop further. For human consumption, temperature primarily influences taste perception. Many people find water most palatable when cool but not ice cold. In backcountry settings, boiling water remains an important safety practice, as sustained boiling can kill many harmful bacteria, viruses, and protozoa.
Water clarity refers to how easily light penetrates the water column. It is influenced by suspended particles such as sediment, algae, and organic matter. While cloudy water may indicate runoff, erosion, or contamination, clarity alone does not determine whether water is safe to drink. Clear water can still contain dissolved pollutants or microorganisms. In lakes, clarity is often measured using a Secchi disk—a round, marked disk lowered into the water until it is no longer visible. The depth at which it disappears provides an estimate of transparency.
Conductivity is another key indicator of water quality. Measured in microsiemens per centimeter (µS/cm), conductivity reflects the water’s ability to conduct electricity, which depends on the concentration of dissolved ions such as calcium, magnesium, sodium, chloride, sulfate, and nitrate. Freshwater streams often range between 100 and 1,000 µS/cm, though pristine waters may fall well below that range. Significant deviations from normal baseline levels can indicate pollution, runoff, or other environmental changes.
The pH level—short for “potential of hydrogen”—measures the concentration of hydrogen ions in water and indicates its acidity or alkalinity. The pH scale runs from 0 to 14, with 7 considered neutral. Values below 7 indicate acidity, while values above 7 indicate alkalinity. The Environmental Protection Agency (EPA) recommends that drinking water fall within a range of 6.5 to 8.5. Water outside this range can cause corrosion in pipes, affect taste, or indicate contamination issues.
Dissolved oxygen (DO) measures the amount of oxygen gas dissolved in water and is essential for aquatic organisms. Oxygen enters water through atmospheric exchange and through photosynthesis by aquatic plants. Fast-moving water, such as streams and waterfalls, tends to have higher dissolved oxygen levels than stagnant ponds. Healthy freshwater systems commonly maintain dissolved oxygen levels between 6 and 9 milligrams per liter (mg/L). While dissolved oxygen is critical for ecosystem health, it has minimal direct impact on drinking water taste in treated systems.
Andrew Schry also advises homeowners about chlorine levels, iron content, and water hardness. Hardness refers specifically to the concentration of dissolved calcium and magnesium ions in water. It is typically expressed in milligrams per liter (mg/L) as calcium carbonate. Water is generally classified as soft (0–60 mg/L), moderately hard (61–120 mg/L), hard (121–180 mg/L), or very hard (above 180 mg/L). While hard water is not a health hazard—and may contribute beneficial minerals—it can lead to scale buildup in pipes and appliances, reduce soap efficiency, and leave residue on fixtures.
When hardness levels become excessive, water softening systems may be recommended. These systems typically use ion exchange, replacing calcium and magnesium ions with sodium or potassium ions to reduce scaling. Unlike hardness, alkalinity refers to water’s buffering capacity against changes in pH and is measured separately.
Understanding these elements allows homeowners and outdoor enthusiasts alike to make informed decisions about treatment, filtration, and safe consumption. For professionals such as Andrew Schry, evaluating water quality means looking beyond a single metric and assessing the full chemical and physical profile that determines how water performs in everyday use.
