Health Hygiene & Sanitation

Lesson 27 : Water Purification

Purification Of Water On A Small Scale

Disinfection Of Wells

Wells are the main source of water supply in the rural areas. The need often arises to disinfect them, sometimes on a mass scale, during epidemics of cholera and gastroenteritis. The most effective and cheapest method of disinfecting wells is by bleaching powder. Potassium permanganate should not ­be used as it is not a satisfactory disinfecting agent.

Steps in Well Disinfection

• Find the volume of water in a well
• Find the amount of bleaching powder required for disinfection
• Dissolve bleaching powder in water
• Delivery of chlorine solution into the well
• Allow a contact period of one hour before the water is drawn for use
• Orthotolidine arsenite test