What Happens After You Flush

How our waste products are processed to provide pure water and prevent the spread of fatal diseases.

When you go to the toilet and flush away your waste, how is it treated to stop it polluting our environment? Up until the 19th Century, no one really cared where it went, but with the growth of towns and cities, human waste became a huge problem.

Besides toilet paper and other solid material sent down the loo, solid human waste contains harmful bacteria that can easily spread disease, as well as phosphates and nitrogens that encourage the growth of algae when it is released into bodies of water. The algae fouls waterways and blocks light, thereby preventing the ability for fish and other creatures to see or breathe properly. The waste also reduces the oxygen in water due to the decomposition of bacteria. This, along with its dirty colour and the stink it causes due to the release of hydrogen sulphide gas caused by its nitrogen-rich bacteria, all make our waste highly unpleasant and deadly to our environment and ourselves.

The solution in the developed world was to link the new flushing toilets to vast underground sewage systems, to take the waste away from the towns to rivers or the sea. This just moved the problem away from the towns, but in the 20th Century sewage treatment plants were developed and improved. These treatment plants separate the solids from the liquids, and the waste that cannot be processed and recycled is sent to landfill or incineration.

Strict laws and regulations in the developed world control where and how treatment plants discharge waste, but in many countries sewage is still released without any type of treatment.

Waterbome diseases

Waterborne diseases are spread by damaged or non-existent sewer systems, pollution and natural disasters. They tend to be caused when animal and human urine or faeces gets into the water supply and encourage the proliferation of deadly viruses and bacteria.

Diarrhoea is a common symptom of waterborne disease. Every day at least 5,000 children die of diarrhoea-related diseases due to bad sanitation. Diarrhoea exhibits itself as frequent evacuation of watery faeces and can last several days. Cholera bacterium in untreated water causes severe vomiting and diarrhoea, leading to dehydration and life-threatening consequences. If diarrhoea-infected faeces should enter the water supply, it helps to spread the disease even further in the population.

Arsenic in water supplies can cause cancer of the kidney, lungs, bladder or skin. For example, in Bangladesh the World Health Organization estimates that 77 million people are exposed to high levels of arsenic in groundwater, which is the main source of fresh water.

Unsanitary water, food and hygiene standards can also cause hepatitis A and C. This causes an inflammation of the liver and is highly contagious.