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Health Effect which may be

caused by mixing of sewer line

and water supply

By:Muhammad Rehan Tahir

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" I think the problem today is that turning onyour tap is an act of faith, and I'm not sure

that that act of faith is particularly well-placed If you drink from the tap, there are

several recent studies you should know aboutbecause they may change the way you think

about your water

(David Ozonoff, Chairman, Environmental Health Department,

Boston University)

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Contamination of Drinking Water

Contamination of drinking water sources by

sewage can occur from

raw sewage overflow

septic tanks

leaking sewer lines

land application of sludge partially treated waste water

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Contamination of Drinking Water

Sewage itself is a complex mixture and can

contain many types of contaminants.

The greatest threats posed to water resources

arise from contamination by bacteria, nitrates,

metals, trace quantities of toxic materials, and

salts.

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Seepage overflow into drinking water sources

can cause disease from the ingestion of

microorganisms such as

E coli

Giardia

Cryptosporidium Hepatitis A

Helminths

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Raw Sewage Overflow

Storm water systems in urban areas are sometimescombined with sanitary sewer systems route to sewagetreatment plants.

Excessive storm water can cause this joint system to

overflow. In this event, excess flow will be directed intowaterways untreated, resulting in sewage contamination.

Urban runoff is usually collected by a separate storm sewersystem and discharged directly into waterways.

Combined systems are cheaper, but the potential to harm

health is higher. Some systems have diversions to accommodate heavy flow.

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Septic Tanks

Septic tanks contaminate 1% of the nationsusable aquifers.

Septic tanks are enclosures that store andprocess wastes where no sewer system exists,such as in rural areas or on boats.

Treatment of waste in septic tanks occurs bybacterial decomposition. The resulting material iscalled sludge.

Large portions of the population are still servedby septic systems as opposed to public wastetreatment facilities.

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Contamination of Water by

Septic Tanks

Contamination of water from septic tanks occurs

under various conditions:

Poor placement of septic leach fields Badly constructed percolation systems

System failure

High density placement of tanks

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Four Groups of Contaminants

Microbial Pathogens

Organics

Inorganic Radioactive Elements

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Microbial Pathogens

Pathogens in drinking water are serious health risks.

Pathogens are disease-producing micro-organisms,which include bacteria such as giardia lamblia, viruses,and parasites.

They get into drinking water when the water source iscontaminated by sewage.

They can cause gastroenteritis, salmonella infection,dysentery, shigellosis, hepatitis, and giardiasis.

The presence of coli form bacteria, which is generally aharmless bacteria, may indicate other contamination tothe drinking water system.

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Organics

This group of contaminants includes:

Trihalomthanes (THMs), which are formed when chlorine in treateddrinking water combines with naturally occurring organic matter.

Pesticides, including herbicides, insecticides, and fungicides.

Volatile organic chemicals (VOCs), which include solvents,degreasers, adhesives, gasoline additives, and fuels additives.

Some of the common VOCs are: benzene, trichloroethylene (TCE),styrene, toluene, and vinyl chloride.

Possible chronic health effects include cancer, central nervoussystem disorders, liver and kidney damage, reproductive disorders,

and birth defects.

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Inorganic

These contaminants include toxic metals like arsenic,barium, chromium, lead, mercury, and silver. Thesemetals can get into your drinking water from naturalsources, industrial processes, and the materials used in

your plumbing system.

Toxic metals are regulated in public water suppliesbecause they can cause acute poisoning, cancer, andother health effects.

Nitrate is another inorganic contaminant. The nitrate insewage can contaminate water. Nitrate has beenassociated with "blue baby syndrome" in infants.

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Radioactive Elements

Radon is a radioactive contaminant that

results from the decay of uranium in soils and

rocks. It is usually more of a health concern

when it enters a home as a soil gas than when

it occurs in water supplies. Radon in air is

associated with lung cancer.

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Causes of Waterborne Diseases

Waterborne disease can be caused by protozoa,viruses, or bacteria, many of which are intestinalparasites

This is likely to occur where public and privatedrinking water systems get their water fromsurface waters (rain, creeks, rivers, lakes etc.),which can be contaminated by infected animalsor people.

Runoff from landfills, septic fields, sewer pipes,residential or industrial developments can alsosometimes contaminate surface water.

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Causes of Waterborne Diseases

This has been the cause of many dramatic

outbreaks of faecal-oral diseases such as

cholera and typhoid.

The germs in the faeces can cause the

diseases by even slight contact and transfer.

This contamination may occur due to

floodwaters, water runoff from landfills, septicfields, and sewer pipes.

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Water-related diseases

Water, sanitation and hygiene have important impactson both health and disease.

Water-related diseases include those due to micro-organisms and chemicals in water people drink;diseases like schistosomiasis which have part of theirlifecycle in water; diseases like malaria with water-related vectors; drowning and some injuries; andothers such as legionellosis carried by aerosols

containing certain micro-organisms. Water also contributes to health, for example through

hygiene

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Prevention

The only way to break the continued transmissionis to improve the peoples hygienic behaviour andto provide them with certain basic needs:drinking water, washing and bathing facilities and

sanitation. Malaria transmission is facilitatedwhen large numbers of people sleep outdoorsduring hot weather, or sleep in houses that haveno protection against invading mosquitoes.

Malaria mosquitoes, tropical black flies, andbilharzias snails can all be controlled withefficient drainage because they all depend onwater to complete their life cycles.

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Prevention

Clean water is a pre-requisite for reducing the spread ofwater-borne diseases. It is well recognised that theprevalence of water-borne diseases can be greatly reducedby provision of clean drinking water and safe disposal offaeces.

Water is disinfected to kill any pathogens that may bepresent in the water supply and to prevent them fromgrowing again in the distribution systems. Disinfection isthen used to prevent the growth of pathogenic organisms

and to protect public health and the choice of the disinfectdepends upon the individual water quality and watersupply system.

http://www.lenntech.com/disinfection.htmhttp://www.lenntech.com/disinfection.htmhttp://www.lenntech.com/disinfection.htm

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Summary

As people hear about the possibility ofcontaminants in their drinking water, they worryabout potential health effects.

Water supplies once considered to be pure mayhave various contaminants, often from naturalsources. These are usually at levels below thoseconsidered to be harmful.

If you are concerned, test your water. For more

information on water quality, testing, andtreatment, contact the Extension Center or healthdepartment in your county or your physician.

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References

Home Water Quality and Safety. Haman, Dorata Z. andBoucher, Del B. Florida Cooperative Ex tension Service.University of Florida. Pub. No. 14M-86.1986.

Health Effects of Drinking Water Contaminants.Stewart, Judith C., Lemley, Ann T., Hogan, Sharon I. andWeismiller, Richard A. Cornell University and theUniversity of Maryland. Fact Sheet 2.1989.

Drinking Water: Present Problems, Future Directions .

Nutrition Clinics. Woodruff, Sandra L. Vol. 5, No.2,1990: 1-21.