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Untreated Sewage

What is this?

Developing countries often lack adequate water treatment facilities, and as a result thousands of people die or become ill each year due to waterborne pathogens.

The term sewage is used to describe liquid wastes containing a mixture of human feces and wastewater from non-industrial human activities such as bathing, washing, and cleaning.  In many third world countries without practical alternatives for purifying the water, this sewage is dumped into local waterways. 

Considered a major risk to human health, this wastewater contains waterborne pathogens that can cause serious human illness.  

Untreated sewage also destroys aquatic ecosystems, threatening human livelihoods, when the biological oxygen demand and nutrient-loading deplete the water's oxygen levels. 

What impact does it have?

The World Health Organization (WHO) estimates that 2.6 billion people had no access to adequate sanitation facilities in 2008.  

The report found the lowest coverage in:

Sub-Saharan Africa (37%)

Southern Asia (38%)

Eastern Asia (45%)

Improved sanitation facilities eliminate human contact with fecal material and include flush or pit toilets/latrines and composting toilets.  But these facilities are few and far between.

Even where water-based toilets are available, the waste is often just discharged into drains and streams, in the absence of collection and treatment systems.  As a result, surface waters in many urban areas are highly contaminated with human waste. In areas with pit latrines, seepage into local groundwater is often a major problem, since many communities rely on shallow wells for drinking water.

Lack of access to improved sanitation disproportionately affects poor communities in urban and rural areas where resources for investments in collection and treatment infrastructure are scarce.  However, the challenge of maintaining existing systems to protect humans from waterborne disease outbreaks affects even affluent areas of the world.

Exposure Pathways

Intentionally - Sewage can be intentionally discharged to waterways through pipes or open defecation.

Unintentionally - Sewage is unintentionally disseminated during rainfall events.

When humans use these waterways for drinking, bathing, or washing, they are exposed to the associated pathogens, many of which can live for extended periods of time in aquatic environments.  People get sick from drinking contaminated water, getting it on/in skin, eyes or ears, or from preparing foods with contaminated water. Similarly, human illness can arise from inhaling contaminated water droplets.

Health Effects

Life-threatening human pathogens carried by sewage include cholera, typhoid and dysentery.

Other diseases resulting from sewage contamination of water include

  • Schistosomiasis
  • Hepatitis A
  • Intestinal nematode infections
  • Numerous other diseases and forms of digestive illnesses

The WHO estimates that 1.5 million preventable deaths per year result from unsafe water, or less than adequate sanitation or hygiene.  These deaths are mostly young children. Another 860,000 children less than five years old are estimated to die annually as a result of the malnutrition associated with repeated diarrhea or intestinal nematode infections.

What has been done about it?

Awareness has been raised on this issue over the past several years, and globally the situation IS improving.  

A number of interventions have already proven effective in reducing the diarrheal disease burden resulting from inadequate sanitation.  These range from hand washing and hygiene education, to toilet/latrine installation and point-of-use water treatment, to approaches comprised of multiple strategies.

Is this action working?

This action is working, although the issue remains a challenge.  The WHO estimated in 2004, only 3.8 billion people had access to improved sanitation.  By 2008, the estimate was 2.6 million.  The WHO has set an aggressive target of at least 75% global water treatment coverage by the year 2015.

References

  • http://www.worstpolluted.org/projects_reports/display/63
  • http://blogs.nationalgeographic.com/blogs/news/chiefeditor/2008/08/water-crisis.html
Submitted by Petra Mayfair on Sep 1, 2009