Water Quality and Health

Water Quality Basics - H2Know Essentials

• Potable Water: Safe to drink, palatable, free from pathogens & harmful chemicals.
• Key Parameters:
  • Physical: Turbidity (ideal <1 NTU, max acceptable <5 NTU), Color, Odor, Taste.
  • Chemical:
    • pH: 6.5-8.5.
    • Hardness: Temporary (bicarbonates), Permanent (sulfates, chlorides of Ca/Mg). Desirable <200 mg/L as $CaCO_3$.
    • Fluoride: Optimum 0.5-0.8 mg/L. >1.5 mg/L causes dental fluorosis.
    • Nitrates: <45 mg/L (prevents infant methemoglobinemia).
    • Residual Chlorine: Min 0.5 mg/L after 1 hr contact time.
  • Microbiological: E. coli (indicator of fecal pollution) - must be 0 per 100mL.

⭐ The most important bacteriological indicator of water quality is E. coli; its presence indicates recent fecal contamination. oka

Aqua Ailments - Pathogen Parade

⭐ Hepatitis E in pregnancy (3rd trimester) has high risk of fulminant hepatic failure & maternal mortality (~20%).

Purity Parameters - Safe Sip Standards

Key water purity indicators: Physical (e.g., turbidity), Chemical (e.g., pH, hardness, arsenic), and Bacteriological (e.g., E.coli). Governed by Indian Standard IS 10500:2012.

Purification Processes - Cleanse & Clarify

Household Level:

• Boiling: Vigorous for 10-20 mins kills bacteria, spores, cysts.
• Chemical Disinfection:
  • Bleaching powder (stabilized).
  • Chlorine solution/tablets (target: 0.5 mg/L free residual chlorine for 1 hr).
  • Iodine, KMnO₄ (for wells).
• Filtration: Ceramic filters (e.g., Katadyn), UV filters.
• Solar Disinfection (SODIS): 6 hours in sunlight.

Municipal Level (Large Scale):

• Filtration:
  • Slow Sand Filter (SSF): Vital layer (Schmutzdecke), cleaning 1-3 months. Rate: 0.1-0.4 m³/hr/m².
  • Rapid Sand Filter (RSF): Backwashing daily. Rate: 5-15 m³/hr/m².

⭐ Horrock's apparatus is used to estimate the chlorine demand of water, ensuring adequate disinfection with bleaching powder. Minimum recommended free residual chlorine: 0.5 mg/L after 1 hour contact.

Disease Defense - Water Watch Wisdom

• Prevention: Source protection (sanitary wells, catchment security), point-of-use (POU) treatment, safe storage.
• Surveillance:
  • NWQMP (CPCB): monitors surface & groundwater quality.
  • IDSP: tracks waterborne disease outbreaks for rapid response.
• Legislation: Water (P&CP) Act 1974; Environment (Protection) Act 1986.
• Outbreak Steps: Confirm, define case, describe (TPP), find source, control.

⭐ Common-source waterborne outbreaks typically show a pointed epidemic curve (single exposure).

High‑Yield Points - ⚡ Biggest Takeaways

• Key waterborne diseases: cholera, typhoid, hepatitis A/E, and bacillary dysentery.
• E. coli is the prime indicator of recent fecal contamination in drinking water.
• Maintain free residual chlorine at 0.5 mg/L for 30 minutes contact time.
• Excess fluoride (>1.5 mg/L) causes dental mottling and skeletal fluorosis.
• High nitrates (>45 mg/L) in water lead to infant methaemoglobinaemia.
• Temporary hardness (bicarbonates) removed by boiling; permanent (sulfates/chlorides) not.
• Chlorination is the most common method for large-scale disinfection of water.