Factors Affect Sewerage

External Factors

Internal Factors

 Animal and human excrement

Industrial sewage

Industrial waste –chemical and organic fats and grease

Dangerous and poisonous materials – heavy metals, acids, poisonous gases, radio-active materials

construction and road rubble

Bacteria

Stones, planks, rags

Miscellaneous: objects, wet wipes, waste disposal

Damage caused by infrastructure authorities operations

 Unstable earth

Ground water pressure

Plant root penetration

Various upheavals