You are here

Disinfection of Wells during an Emergency – The Double Pot Method

Disinfection of Wells during an Emergency – The Double Pot Method
E.g. an outbreak of cholera
• During an emergency, it is desirable to ensure a constant dosage of chlorine to well water
• One method of doing this is the ‘Double pot method’
• The method is an improvement devised by the National Environmental Engineering Research Institute (NEERI), Nagpur, India
• There are two cylindrical pots
• One pot is placed inside the other
• Outer pot:
 Inside height is 30 cm
 Inside diameter is 25 cm
 A hole (1 cm diameter) is made at 4 cm above the bottom
• Inside pot:
 Fits into the outer pot
 Has a hole (1 cm diameter) near the upper end
• A mixture of 1 Kg bleaching powder and 2 Kg sand is prepared and moistened with some water
• The inner pot is filled with this mixture up to 3 cm below the hole
• The inner pot is placed into the outer one
• The mouth of the latter is closed with polyethylene foil
• The double pot is lowered into the well by means of a rope attached to the well kerb
• The pot should be immersed at least 1 m below the water level to prevent damage by the buckets used for drawing water
• This device works satisfactorily for 2 – 3 weeks in small household wells containing 4500 L of water and a draw off rate of 360 to 450 L per day

OT and OTA test:

Membrane processes in water purification:

Super Chlorination and Break Point Chlorination:

Slow sand filter:

Rapid sand filter:

Purification of water at a large scale:

Criteria for a Chemical to be Suitable as Water Disinfectant in Water Supplies:

Water Supplies Disinfection with Chlorination:

Principles of Chlorination:

Methods of Chlorination in Water Supplies:

Horrock's Apparatus:

Disinfection of well during emergency:

Double Pot method:

Disinfection of Wells:

OT and OTA test:

Domestic or Household Purification of Water: