Water Tank Cleaning in Lebanon: Frequency, Method, and Disinfection

Lebanese buildings store water in concrete ground tanks, polyethylene rooftop tanks, and stainless steel cisterns. Sediment, biofilm, and algae build up. WHO recommends cleaning at least once a year — more often if water is visibly cloudy or has odour.

How often

• Annual: minimum for any potable water tank.
• Every 6 months: tanks in warm South Lebanon or with intermittent supply.
• After contamination event: dead animal, sewage backflow, flood, repairs.

The proper method

• Empty the tank completely; isolate inlet/outlet.
• Remove sediment manually — buckets, brushes, vacuum.
• Scrub walls and floor with food-safe cleaner; rinse to drain.
• Inspect for cracks, rust (steel), or UV damage (polyethylene).
• Disinfect, rinse, and refill.

Safe disinfectants

• Sodium hypochlorite (chlorine bleach): 50–200 ppm for shock dose, contact 1 hour, then rinse and refill. Standard.
• Hydrogen peroxide: alternative for chlorine-sensitive systems.
• Avoid: household detergents, scented soaps, ammonia — never use them in drinking water tanks.

Choosing a cleaning service

• Ask if they use confined-space training for ground tanks.
• Should provide before/after photos and a written certificate.
• Confirm potable-grade chemicals and rinse procedure.
• Get a water test (free chlorine, turbidity) after refill.