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Water appears cloudy or foggy due to turbidity - the presence of finely divided solid particles in water. These particles may be inorganic mineral matter which does not dissolve, or organic matter that has been picked up as the water flows over and through the ground. The particles cause the scattering and absorption of light rays, which give the water a cloudy appearance.
Whether turbidity is due to suspended organic or inorganic matter, it can cause staining of sinks and fixtures, and the discoloration of laundered fabrics. Inorganic turbidity can have an abrasive effect on plumbing systems and may cause physical wear or erosion on pipes and fittings. Turbidity is most commonly found at taps whose source is surface water from lakes, streams, or ponds.
Excess chlorine from the disinfection treatment of water can make the water objectionable. Water with a high mineral concentration may have an unpleasant soda or salty taste. A metallic taste may be produced by the presence of iron or manganese in water.
Hydrogen sulfide gas (rotten egg gas) in water has an objectionable odor. As little as 0.5 ppm hydrogen sulfide can be tasted in drinking water. As water is drawn to the surface, hydrogen sulfide gas can be released to the atmosphere. In strong concentrations, this gas is flammable and poisonous. It rapidly tarnishes silver, turning it black and in sufficient quantities it is toxic to aquarium fish.
Organic matter in water even in small amounts can cause unusual tastes and odors such as musty, fishy, or earthy smells.
Tastes and odors of water affect foods and beverages prepared with the water.
Microscopic organic suspended particles can cause a yellowish coloration which can make the water unappealing to drink, and may cause the staining of surfaces and materials touched by the water. This color condition presents no health hazard. It is more common in surface water supplies and shallow wells than in deep wells in regions where the water passes through marshlands and has percolated down through peaty soils.
Humic acids, often referred to as tannins, are the real cause
of the color condition. Often the color is not highly visible
in a glass of water, but can be noticed when water is drawn for
a bath. The white porcelain background of the tub can highlight
even the slightest discoloration.
Water with iron in it, depending on the type and state of the iron, may or may not be clear when it is first drawn but may turn a brown-red color when it stands exposed to air or when it is heated. Water containing significant amounts of iron can leave brown-red stains on fixtures and dishes, as well as discolor laundry. It is also unappealing for drinking.
Activated carbon filters are effective in reducing most of these aesthetic problems. These filters are specially designed for the removal of solid particles from the water. Activated carbon has the ability to absorb (bind to its surface) soluble organic compounds and certain gases. It is specially suited for use in water treatment. It acts as a fine screen which traps solid particles and allows the water to pass through. Activated carbon filters are available in three forms: solid block, precoat, and granular.
Turbidity - the fine particles that cause a cloudy appearance may also be removed with an activated carbon filter, or a particulate filter.
For high concentrations of hydrogen sulfide, a chlorination system with activated carbon filtration would be the best solution. Activated carbon filters will remove low concentrations of hydrogen sulfide.
If the problem is serious then use ion exchange or reverse osmosis or a distillation system
Water colored as a result of humic acids is best treated with anion exchange resin. The resin absorbs the organic bodies that cause the discoloration, and will leave behind clear water.
For color problems that are due to low or moderate levels of dissolved iron, a household water softener may remove the impurity. The soluble iron is removed from the water by ion exchange, in the same way that hardness is removed.
If much of the iron is already precipitated, or the iron concentration
is too high for a water softener, an iron removal filter
should be used. The filter forms a barrier that prevents the continued
passage in the water.
Aeration consists of breaking the incoming water into small droplets
(spray), drawing fresh air through that spray, collecting the
water into a storage tank, re-pressurizing the water, and passing
it through a particulate filter to catch any particles that might
be carried out of the storage tank. The air drawn though the spray
must be vented outside the house -- remember, it is toxic and
explosive. Although this system necessitates another pump to re-pressurize
your supply, you are not adding any chemicals to your water, which
makes it attractive. This system is low maintenance with no chemicals
to purchase. Initial cost may be higher, however, and space requirements
may be greater.
Prepared by Trevor Croll,
42 Pearse Street, Keperra, Queensland Australia, 4054.
Phone 61 7 3855 1115