Parameters to Assess Water Quality for Consumption
Water quality assessment is crucial for ensuring the safety and suitability of water for human consumption. Various physical, chemical, and biological parameters are used to evaluate water quality. These parameters help determine whether water meets health standards and is free from contaminants that can pose risks to human health. Below are the key parameters used to assess water quality:
1. Physical Parameters
a. Temperature
- Temperature influences the solubility of gases and minerals in water. Warmer water tends to dissolve less oxygen, affecting aquatic life and microbial activity.
- For drinking water, temperature should be moderate to avoid unpalatability.
b. Turbidity
- Turbidity measures the cloudiness of water caused by suspended particles like silt, clay, and microorganisms.
- High turbidity can indicate contamination and interfere with disinfection processes.
- Acceptable limit: Less than 1 NTU (Nephelometric Turbidity Units) as per WHO guidelines.
c. Color, Odor, and Taste
- Water for consumption should be colorless, odorless, and free from unpleasant taste.
- These attributes are assessed to detect contamination by organic matter, chemicals, or metals.
d. Total Dissolved Solids (TDS)
- TDS measures the concentration of dissolved minerals, salts, and metals in water.
- High TDS levels affect the taste and may pose health risks.
- Acceptable limit: 500 mg/L (WHO standard).
2. Chemical Parameters
a. pH
- pH indicates the acidity or alkalinity of water on a scale of 0–14.
- Drinking water should be neutral to slightly alkaline (pH 6.5–8.5).
- Extremes of pH can corrode pipes and harm human health.
b. Hardness
- Hardness is caused by calcium and magnesium ions in water.
- While not harmful to health, excessive hardness affects taste and can cause scaling in pipes.
- Acceptable limit: 300 mg/L (as CaCO₃).
c. Dissolved Oxygen (DO)
- DO measures the oxygen available in water.
- Adequate DO levels indicate good water quality, while low levels may suggest pollution by organic matter.
d. Chemical Contaminants
- Nitrates and Nitrites: High concentrations (e.g., from fertilizers) can cause methemoglobinemia (“blue baby syndrome”) in infants.
- Acceptable limit: Nitrate (NO₃): 50 mg/L; Nitrite (NO₂): 3 mg/L.
- Fluoride: Essential in small amounts for dental health but harmful in excess, causing fluorosis.
- Acceptable limit: 1.5 mg/L.
- Arsenic: A toxic contaminant that can cause cancer and skin lesions.
- Acceptable limit: 0.01 mg/L.
e. Heavy Metals
- Metals like lead, mercury, cadmium, and chromium are toxic even in small amounts and can lead to severe health issues such as neurological damage and organ failure.
- Acceptable limits (WHO standards):
- Lead: 0.01 mg/L
- Mercury: 0.006 mg/L
- Cadmium: 0.003 mg/L
f. Chlorine
- Residual chlorine is used as a disinfectant, but excessive amounts affect the taste and can form harmful by-products.
- Acceptable limit: 0.2–0.5 mg/L.
3. Biological Parameters
a. Microbial Contamination
- Water is assessed for harmful microorganisms like bacteria, viruses, and protozoa that can cause diseases.
- Coliform Bacteria: Presence indicates fecal contamination.
- E. coli: Indicates recent contamination with human or animal waste.
- Acceptable limit: Zero coliforms or E. coli per 100 mL of water.
b. Pathogens
- Testing for waterborne pathogens like Giardia, Cryptosporidium, and Vibrio cholerae is essential for preventing outbreaks of diseases such as cholera, typhoid, and dysentery.
4. Radiological Parameters
a. Radioactive Contaminants
- Radionuclides like uranium, radium, and radon can contaminate water naturally or through industrial waste.
- Long-term exposure increases the risk of cancer.
- Acceptable limits (WHO standards):
- Gross Alpha Activity: 0.5 Bq/L.
- Gross Beta Activity: 1 Bq/L.
Conclusion
Assessing water quality for consumption involves a comprehensive analysis of physical, chemical, biological, and radiological parameters. Each parameter provides insight into potential contaminants and their impact on health. Ensuring compliance with standards set by organizations like WHO and local regulatory bodies is essential for delivering safe and potable water to populations. Regular monitoring, treatment, and public awareness are vital to maintaining high water quality and protecting public health.