Sources of Water

Sources of Water & its Impurities

Water is primary derived from the ocean & seen on surface & ground through hydrological becomes loaded with moisture & at lower temperatures the moisture precipitates on to earth as rain, snow, fog, dew or frozen rain. Thus there are three 

Sources:

• Rain Water.
• Surface Water
  • Impounding Reservoir.
  • Tanks, ponds & lakes.
• Ground Water
  • Springs.
  • Tube Well.
  • Rivers & Streams.

Rain Water

Rain is the main source of water & it is the purest form in nature. On reaching the surface of the earth, part of it is evaporated, part of it flows to form rivers, helps to fed tanks & lakes, while the rest of it reaches subsoil to become springs or ground water.

Source of Impurities

As rain water travels it absorbs gases, collects dirt etc. So it may contain nitrogen, oxygen & carbonic acid. Near the sea it collects common salt & sulphate & in towns ammonia, acids, dust microbes etc.

Characteristic of Rain Water

• Physically, it is clear, bright & sparkling It is chemically soft, has a flat taste, and is clean. 
• Being soft it has a corrosive action on lead pipes.
• Biologically, it is free from pathogenic agents but not sterile as it collects gases, dirt, dust etc. So needs to be boiled or disinfected before drinking.

Surface Water

Rainwater, which includes water from rivers, tanks, lakes, reservoirs, and the sea, is another source of surface water. Water on the surface is vulnerable to pollution by people, animals, and other sources. It can never be purified to the point of being safe for human consumption. Most of the people in Nepal depend on surface water & most of water supply system is based on it as Sundarijal, Shivapuri etc.

The types of surface water are:

• Impounding reservoirs.
• Rivers & streams.
• Tanks, ponds & lakes.

Impounding Reservoirs: This is the artificially constructed lake made up of earth work or stonework in which large quantities of surface water is stored. 

• These reservoirs provide good quality of water, soft usually clear, pleasant to the taste & safe except rain water.
• It is usually soft & free from pathogenic organisms.
• It is usually furnish a fairly good quality of water.

Sources of Impurities

However, if this catchment region is not adequately secured, the water may be tainted with tiny organisms and algal growth. Therefore, the catchment region should be far from where people and animals live. It's frequently false to say that mountain streams have exceptionally pure water.

Rivers & Streams:

The other main sources of water are rivers & stream. But they grossly polluted & quiet unfit for drinking without treatment.

Characteristics

• They are turbid during rainy season & clear at other season.
• River water contains dissolved & suspended impurities of all kinds derived from surface washing sewage & sullage water, industrial, trade & hospital waste, drainage etc.
• They have high amount of pathogenic organisms including parasites. So, it should be purified before it is used for drinking purposes.
• River water is usually soft unless it passes through rocks containing silts.

Sources of Impurities

The impurities of river water are derived from surface washings, sewage & sullage water, industrial & trade wastes, & drainage from agricultural areas. The customs & habits of the people like bathing animal washing & disposal of the dead, all add to the pollution of water.

Tanks, Ponds & Lakes:

These are large excavations in which surface water is stored where there is no central pipeline water supply.

Sources of Impurities

1. They are prone to contamination by human & animals as washing, bathing, cleaning vehicles, cleaning the cattle, & swimming etc.
2. Children defecate around the tanks which are washed by rain & became contaminated so highly dangerous for drinking.
3. Older tanks may get aquatic vegetation.
4. Added to this the surface drains are allowed to drain into the tanks & ponds. Hence, the contamination in tanks is unavoidable.

Ground Water

Rain water percolating into ground constitutes ground water. Ground water is the cheapest & most practical way of providing water to small communities. Ground water is safer than surface water, because the ground itself acts as a successful filtering medium.

Characteristics

• It is likely to be free from bacterial infection.
• It usually requires no treatment.
• Supply is adequate even in dry seasons.
• It is less subject to contamination than surface water.
• The mineral contents like calcium & magnesium salts may be high resulting in chemical harness of water.
•  It needs a pump or some other method to lift the water.

The sources of ground water are

•  Wells,
• Tube well,
• Springs.

Wells

Traditionally & even today wells are an important  source of water supply in rural as well as urban areas. Wells are defined as artificial holes or pits sunk deep into the earth to reach water level into which the subsoil water percolates. The wells can be classified into various types as follows

• According to technical or depth of well:
  • Shallow Wells: These wells tap the topmost subsoil water i.e., the water from above the first impervious layer in the ground. Shallow wells are liable to pollution from neighboring source of contamination such as latrine, drain, soakage pit, cesspools, and collection of manure. Shallow wells are not same to community if they are not made sanitary.
  • Deep Wells: A deep well is the one which tap water from the water bearing stratum below the first impervious layer in the ground. Deep well as usually machine-dug & may be several hundred meters deep. They provide comparatively safe water for drinking than shallow wells, because their water travels a greater distance through the earth there by getting better protection through efficient filtration. The wa of these wells is usually
• According to methods of construction:
  • Katcha Well: It is a hole dug into the water bearing stratum. It is easily contaminated & dry.
  • Pucca Well: It is an open well built of bricks or stone. It dries early but does not get contaminated easily.
  • Step Well: It is a kind of pucca well where steps are constructed to enable people to descend into the well to go for & bring back water or satisfy their thirst.
• Artesian Well: It is a kind of deep well in which the water rises above the level of ground because it is hold under pressure, between two sandrata. Tessure, The water in this type of well is taped by means of a boring. Artesian wells are similar to deep tube wells.

Sources of Impurities (pollution)

It is evident that the well water gets easily polluted from the following sources:

• Washings from drains, cesspools or latrines if they are close to the wells.
• Surface washings, wide narrow. 
• Cracks & fissures in the well.
• Through bird droppings & leaves if the trees and plants are grown close to the wells.
• Vessels & ropes used for drawing water from the well.
• Rise of subsoil water during rains & floods.

The above factors clearly indicate that a good sanitary well has to meet certain requirements.

Improvement of Well

The sanitary quality of well can be improved by:

• Lining of wall should be raised one or two feet above the ground.
• covering the top with concrete slab.
• keeping one or more hand pump to lift water.
• maintaining proper drainage at least 10 feet in length to prevent soakage & contamination.

Sanitary Well

A sanitary well is one which is well constructed properly located & protected against contamination with a view to yield supply safe water. Following points should be taken into consideration while constructing sanitary well.

• Location: It should be tapped in good soil & should be located not less than 15 meters (50 feet) from the possible Sources of  Water contamination (e.g. latrine, sewage form, open drainage, trenching ground & other sources of pollution) & at least 100-150 feet away from animal pens or sheds if possible.
• Lining: It should be sunk deep in the impervious layer. The lining of the well should be built of bricks or stones in cement up to 6m (20 feet) deep to allow the water enter from the bottom & not from sides of the well. This living should be carried 2-3 feet above the ground level.
• Parapet: A parapet wall around the well up to the height of at least 70-75 cm should be provided above the ground.
• Platform: Along with the parapet wall the platform should be should be mode with cement concrete extending at least 3 feet (1m) in all directions. It should have gentle slope outward leading to a drain built along its edges.
• Drain: A pucca drain should be built to carry off spilled water to a public drain or soakage pit from the well. 
• Cover: The top of the well should be covered well by a cement concrete cover to avoid direct contamination. Studies have shown that proved than an bacteriologically safe for use uncovered well.
• Hand pump: A food sanitary well should be equipped with a hand pump to life the water in a clean manner. If this is not done, then public I will use own buckets or vessels & rope to draw water that will contaminate the water. Therefore, provision of hand pump is satisfactory. A well with fitted pump has better quality of water in bacteriological point of View.
• Public (consumer) responsibility: The provision of sanitary wells does not guarantee freedom from waterborne diseases unless & until the consumers take certain basic precautions at the individual & family level. People should be motivated to maintain strict cleanliness around the well, avoid washing clothes, cleaning animal & human, dumping refuse & wastes etc. Use one common bucket attaching a chain to lift water in order to prevent contamination. This can be achieved- only through health education.
• Quality: The physical chemical & bacteriological quality of water should conform to the acceptable standards of quality of safe & whole some water (drinking water).
• Amount of water: The depth & size of the well vary from place to place. If one wants to know approximately the quantity of water in a well, the followings formula can be used:

D ^ 2 * W * 5 = Number of gallons of water in a well, where

D = Diameter of a well (in feet)

W = Depth of water (feet)

Tube Wells

These can be divided into shallow tube wells & deep tube wells. This is common in Terai & Hilly regions like Kathmandu valley of Nepal. They are bacteriologically safe & cheaper than other sources.

• Shallow Tube Wells: They are suitable when the distance of the water from the surface of the ground is not more than a few feet, generally 18-36 feet deep. It can be bored in gravel, coarse sand or chalk but clay soils or fine sand is not suitable. Shallow tube wells are useful in villages, isolated houses, camps, & festivals. They, however, do not assure constant supply of water.
• Deep Tube Wells: Deep tube wells are sunk by drilling through successive substrata or gravel or rock until a suitable supply of ground water is located. They may be several hundred feet deep & require complicated mechanical drilling equipment & skilled engineering direction. They yield continuous supply even to the extent of 60,000 gallons of water per hour if the hole is 9" in diameter. 

Springs

When the ground water comes into surface & flows freely under natural pressure, it is called a 'spring.' It may be of two types:

• Shallow springs.
• Deep (main) springs.

Shallow Springs: They are the outlet of limited collection of ground water. They are usually intermittent, may quickly dry during summer season.

Deep (main) Springs: These are deep sealed springs issuing water supply through cracks or fissures in the soil. They offer a continuous supply of water do not show seasonal fluctuations in the flow of water. They are a good source of water supply to small communities. Springs are simpler to utilize, as no pumping  is needed to bring the water to the surface. Springs are exposed to contamination. Well built protective structures are necessary to safeguard water quality.

Characteristics of good water:

• It should be chemically soft/free.
• It should be free from bad taste, colour odour, smell, suspended, dissolved impurities & micro organisms.
• It should contain some amount O dissolved oxygen & carbon dioxide ( Co2) & traces of iodine & fluorine but no excess of them. It should be free from iron & should have no action on lead.

Impurities of Water

Water may contain natural as well as acquired impurities:

• Natural Impurities:
  • Dust, dissolved gases such as hydrogen sulphide, carbon dioxide, Nitrogen, Ammonia & oxygen.
  • Dissolved minerals such as salts calcium, magnesium & sodium.
  • Microscopic plants & animals.
  • Suspended impurities such as clay, silt, mud, sand etc. greater thang/ galloon mineral
  • Pathogenic bacterial
• Acquired Impurities:
  • Sewage,
  • Industrial wastes,
  • Agricultural pollution,
  • Physical pollution (Heat & radioactivity are the most serious physical pollution).