Disease-causing germs can be spread from sewage if it is not disposed of properly or if people do not practise proper toilet hygiene (cleanliness). If a sewage disposal system is not properly maintained it will not be able to get rid of the sewage safely. For a sewage system to be properly maintained, all faulty (blocked, damaged, broken or worn-out) parts must be mended as soon as possible after they stop working correctly.

Diseases caused by germs:

  • salmonellosis
  • shigellosis
  • diarrhoea
  • trachoma
  • melioidosis
  • gastroenteritis
  • hepatitis A
Diseases caused by parasites:
  • giardiasis
  • dwarf tapeworm infection
  • threadworm infection
  • hookworm infection
  • strongyloidasis
These disease-causing germs and parasites can be spread:
  • directly by people coming into contact with sewage or toilet waste (this can happen, for example, when people walk through sewage which has leaked onto the ground from broken sewage pipes)
  • indirectly by people:
    • coming into contact with animals such as flies and cockroaches which carry the germs and parasites in or on their bodies. Dogs and cats can carry germs and parasites too
    • drinking water which has been contaminated by sewage
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This is a list of some of the conditions which make it easy for direct or indirect spread of germs and parasites from sewage:
  • Not washing hands after going to the toilet.
Fig.  2.1: Not washing your hands after going to the toilet helps spread germs to food.
Fig. 2.1: Not washing your hands after going to the toilet helps spread germs to food.
  • Sewage or effluent collecting in pools as a result of an overflowing sewage lagoon or broken sewage pipes. This sewage and effluent contains disease-causing germs and parasites and allows mosquitoes to breed
  • Uncovered or broken septic tanks which allow effluent to escape, meaning that people or pets can directly be exposed
  • Blocked, overflowing toilets which make it easy for children to come into contact with germs
  • Leach drains from septic tanks which are too close to drinking water supplies so that effluent soaks through the soil into the water supply