Groundwater and its contamination

Many areas of groundwater and surface water are now contaminated with heavy
metals, POPs (persistent organic pollutants), and nutrients that have an adverse
affect on health. Water-borne diseases and water-caused health problems are
mostly due to inadequate and incompetent management of water resources. Safe
water for all can only be assured when access, sustainability, and equity can be
guaranteed. Access can be defined as the number of people who are guaranteed
safe drinking water and sufficient quantities of it. There has to be an effort to
sustain it, and there has to be a fair and equal distribution of water to all
segments of the society. Urban areas generally have a higher coverage of
safe water than the rural areas. Even within an area there is variation: areas
that can pay for the services have access to safe water whereas areas that
cannot pay for the services have to make do with water from hand pumps and
other sources.


In the urban areas water gets contaminated in many different ways, some of
the most common reasons being leaky water pipe joints in areas where the
water pipe and sewage line pass close together. Sometimes the water gets
polluted at source due to various reasons and mainly due to inflow of sewage
into the source.

Ground water can be contaminated through various sources and some of
these are mentioned below.

Pesticides. Run-off from farms, backyards, and golf courses contain pesticides
such as DDT that in turn contaminate the water. Leechate from landfill sites is
another major contaminating source. Its effects on the ecosystems and health
are endocrine and reproductive damage in wildlife. Groundwater is susceptible to
contamination, as pesticides are mobile in the soil. It is a matter of concern as
these chemicals are persistent in the soil and water.

Sewage. Untreated or inadequately treated municipal sewage is a major
source of groundwater and surface water pollution in the developing countries.
The organic material that is discharged with municipal waste into the
watercourses uses substantial oxygen for biological degradation thereby
upsetting the ecological balance of rivers and lakes. Sewage also carries
microbial pathogens that are the cause of the spread of disease.

Nutrients. Domestic waste water, agricultural run-off, and industrial effluents
contain phosphorus and nitrogen, fertilizer run-off, manure from livestock
operations, which increase the level of nutrients in water bodies and can
cause eutrophication in the lakes and rivers and continue on to the coastal
areas. The nitrates come mainly from the fertilizer that is added to the fields.
Excessive use of fertilizers cause nitrate contamination of groundwater, with
the result that nitrate levels in drinking water is far above the safety levels
recommended. Good agricultural practices can help in reducing the amount of
nitrates in the soil and thereby lower its content in the water.

Synthetic organics. Many of the 100 000 synthetic compounds in use today
are found in the aquatic environment and accumulate in the food chain. POPs
or Persistent organic pollutants, represent the most harmful element for the
ecosystem and for human health, for example, industrial chemicals and
agricultural pesticides. These chemicals can accumulate in fish and cause
serious damage to human health. Where pesticides are used on a large-scale,
groundwater gets contaminated and this leads to the chemical contamination of
drinking water.

Acidification. Acidification of surface water, mainly lakes and reservoirs, is
one of the major environmental impacts of transport over long distance of
air pollutants such as sulphur dioxide from power plants, other heavy industry
such as steel plants, and motor vehicles. This problem is more severe in the US
and in parts of Europe.

Chemicals in drinking water

Chemicals in water can be both naturally occurring or introduced by human
interference and can have serious health effects.

Fluoride. Fluoride in the water is essential for protection against dental
caries and weakening of the bones, but higher levels can have an adverse
effect on health. In India, high fluoride content is found naturally in the waters
in Rajasthan.

Arsenic. Arsenic occurs naturally or is possibly aggrevated by over
powering aquifers and by phosphorus from fertilizers. High concentrations of arsenic in
water can have an adverse effect on health.A few years back, high
concentrations of this element was found in drinking water in six districts
in West Bengal. A majority of people in the area was found suffering from
arsenic skin lesions. It was felt that arsenic contamination in the groundwater
was due to natural causes. The government is trying to provide an alternative
drinking water source and a method through which the arsenic content from
water can be removed.

Lead.
Pipes, fittings, solder, and the service connections of some household
plumbing systems contain lead that contaminates the drinking water source.

Recreational use of water
. Untreated sewage, industrial effluents, and
agricultural waste are often discharged into the water bodies such as the lakes,
coastal areas and rivers endangering their use for recreational purposes such as
swimming and canoeing.

Petrochemicals. Petrochemicals contaminate the groundwater from underground
petroleum storage tanks.

Other heavy metals
. These contaminants come from mining waste and tailings,
landfills, or hazardous waste dumps.

Chlorinated solvents
. Metal and plastic effluents, fabric cleaning, electronic and
aircraft manufacturing are often discharged and contaminate groundwater.

Water-borne diseases are infectious diseases spread primarily through contaminated
water. Though these diseases are spread either directly or through flies or filth,
water is the chief medium for spread of these diseases and hence they are termed
as water-borne diseases.

Most intestinal (enteric) diseases are infectious and are transmitted through
faecal waste. Pathogens – which include virus, bacteria, protozoa, and parasitic
worms – are disease-producing agents found in the faeces of infected persons.
These diseases are more prevalent in areas with poor sanitary conditions. These
pathogens travel through water sources and interfuses directly through persons
handling food and water. Since these diseases are highly infectious, extreme care
and hygiene should be maintained by people looking after an infected patient.
Hepatitis, cholera, dysentery, and typhoid are the more common water-borne
diseases that affect large populations in the tropical regions.

A large number of chemicals that either exist naturally in the land or are
added due to human activity dissolve in the water, thereby contaminating it
and leading to various diseases.

Pesticides. The organophosphates and the carbonates
present in pesticides affect and damage the nervous system and can cause
cancer. Some of the pesticides contain carcinogens that exceed recommended
levels. They contain chlorides that cause reproductive and endocrinal damage.

Lead. Lead is hazardous to health as it accumulates in the body and affects
the central nervous system. Children and pregnant women are most at risk.

Fluoride. Excess fluorides can cause yellowing of the teeth and damage to the
spinal cord and other crippling diseases.

Nitrates. Drinking water that gets contaminated with nitrates can prove fatal
especially to infants that drink formula milk as it restricts the amount of oxygen
that reaches the brain causing the ‘blue baby’ syndrome. It is also linked to
digestive tract cancers. It causes algae to bloom resulting in eutrophication in
surface water.

Petrochemicals. Benzene and other petrochemicals can cause cancer even at
low exposure levels.

Chlorinated solvents. These are linked to reproduction disorders
and to some cancers.

Arsenic. Arsenic poisoning through water can cause liver and nervous system
damage, vascular diseases and also skin cancer.

Other heavy metals. –Heavy metals cause damage to the nervous
system and the kidney, and other metabolic disruptions.

Salts. It makes the fresh water unusable for drinking and irrigation
purposes.

Exposure to polluted water can cause diarrhoea, skin irritation, respiratory
problems, and other diseases, depending on the pollutant that is in the water body.
Stagnant water and other untreated water provide a habitat for the mosquito and
a host of other parasites and insects that cause a large number of diseases
especially in the tropical regions. Among these, malaria is undoubtedly the most
widely distributed and causes most damage to human health.

Published in http://www.edugreen.teri.res.in/EXPLORE/water/health.htm