If the water has an NTU of >50, chlorination alone will not be effective; the water should be treated.
Oxfam Guidelines on Water Treatment for Emergencies
Oxfam Technical Manual on Coagulation and Disinfection Equipment
Oxfam Instruction Manual for Water Filtration Equipment
Considerations in water treatment:
- Find out if you are in an area where there are helminths or protozoa (Giardia and Cryptosporidium) that are resistant to chlorine, and ensure a fine mesh (4–6 microns) is added to the system. Some viruses may also require special treatment.
- Where possible, use gravity flow in the treatment system to avoid double pumping, and avoid constructing plants on flood-prone areas.
- Take great care when disposing of the highly toxic alum residual in the sedimentation tanks so as not to contaminate the ground- or surface-water.