8. Hygiene requirements to water distribution – water supply sources and systems of water distribution. Drinking water safeguard zones.

Water supply in settlements. Hygienic characteristics of water sources and supply systems. Sanitary and hygienic protection of water sources.

1. Water Supply in Settlements

• Is a system for collecting, treating, storing, and distributing water for domestic, public health, and industrial use.
• Water must be accessible, sufficient in quantity, safe, and available year-round.
• Daily requirement:
• Survival: ~2 L/person
• Domestic use: 150–200 L/person/day (drinking, cooking, hygiene, cleaning, laundry, etc.)
• Approximate formula: 30 mL × body weight (kg)
• Sources:
• Surface water: Rivers, lakes, reservoirs – large volume but higher contamination risk.
• Groundwater: Wells, springs, boreholes – usually cleaner but may be polluted by sewage or chemicals.

2. Hygienic Characteristics of Water Sources and Supply Systems

Safe and wholesome water:

• Free from pathogens: bacteria, viruses, protozoa, helminths
• Free from harmful chemicals: heavy metals, nitrates, industrial pollutants
• Pleasant taste, color, and odor

Organoleptic parameters:

• Turbidity: Low; high turbidity indicates suspended particles
• Color: Absent → presence indicates organic matter or metals
• Taste & odor: Neutral → abnormal changes suggest contamination

Physical & chemical standards (Bulgarian guidelines):

• Temperature: 6–16°C
• pH: 6.5–8.5
• Hardness: ≤12 mg eqv/dm³
• Ammonia: ≤0.5 mg/dm³
• Nitrates/Nitrites: ≤50 mg/L and 15 mg/L
• Chlorides/Sulfates: ≤250 mg/L
• Iron & Manganese: Minimized for taste, color, and pipes
• Fluoride: ~1 mg/L for dental protection
• Selenium: Low → ↑ cardiovascular risk; Excess → toxic

The supply system components include:

• Intake structures: which prevent debris and contamination.
• Treatment facilities: which include filtration, sedimentation, and disinfection.
• Distribution network: where pipes and reservoirs must prevent leaks, backflow, and contamination.
• Monitoring: which involves regular microbial, chemical, and physical testing.