Well Water Treatment Guide
Posted: Wednesday, June 27, 2007
by Steve Marzinotto
http://www.wellwaterfilters.net
A water well is an artificial excavation or structure put down by any method such as digging, driving, boring, or drilling for the purposes of withdrawing water from underground aquifers. Well water may be drawn via mechanical pump (such as an electric submersible pump) from a source below the surface of the earth, or drawn using containers, such as buckets, that are raised mechanically, or by hand. Wells can vary greatly in depth, water volume and water quality. Well water typically contains more minerals in solution than surface water and may require water treatment to remove/reduce various unwanted contaminants.
A well is made by reaching ground water in the water table. Ground water is stored naturally below the earth's surface. Most ground water originates as rain or snow that seeps into the ground and collects. Ground water provides about 20 percent of the fresh water used in the United States. Most rural areas, and some cities depend on ground water as their source for water. Most rainwater is absorbed by the ground and fills the tiny spaces between soil particles. However, excess water runs over the top of the soil until it reaches a river, stream, or reservoir. Runoff water brings pollutants it encounters along the way to the reservoir.
As water seeps into the ground, it settles in the pores and cracks of underground rocks and into the spaces between grains of sand and pieces of gravel. In time, the water trickles down into a layer of rock or other material that is water tight. This water tight zone collects the ground water,creating a saturated zone known as an aquifer. Aquifers in the United States are usually made from gravel, sandstone, limestone, or basalt (volcanic rock).
The water in the earth that these wells obtain is at a place in the ground known as the water table. The water table is the level of the ground water below the earth's surface. This table is measured by the depth of the upper limit of the Aquifer. The water table can be lowered by lack of precipitation or overdraft. Overdraft occurs when water is removed from the aquifer at a faster rate than can be naturally replaced by rain or snow. The lowering of the water table causes problems such as land subsidence, surface cracking, sinkholes on the surface, damage to the aquifer's water producing character due to compaction. In coastal areas, overdraft can lead to salt water intrusion. Salt water intrusion occurs in low water tables where drops in water pressure can lead to the ocean backing up into the ground water. In a damp area, the water table can be reached simply by digging. In this case the well walls are usually lined with brick, stone, or concrete in order to keep the sides from caving in on the
well. A dug well can be up to 50 feet deep, and has the greatest diameter of any of the well types. Well water that contains a high number of dissolved minerals is called a mineral well.
Two broad classes of drilled-well types may be distinguished, based on the type of aquifer which the well is completed in: shallow or unconfined wells are completed in the uppermost saturated aquifer at that location (the upper unconfined aquifer); or deep or confined wells, which are sunk through an impermeable stratum down into an aquifer which is sandwiched between two impermeable strata (aquitards or aquicludes). The majority of confined aquifers are classified as artesian because the hydraulic head in a confined well is higher than the level of the top of the aquifer. If the hydraulic head in a confined well is higher than the land surface it is a "flowing" artesian well (named after Artois in France). There clearly are many cases that fall in between these two end members; often unconfined wells may be very deep (what is often called a shallow well can be over 150 m deep) and many times wells are completed across all aquifers from their top to their bottom (especially agricultural or
industrial wells), being open to both unconfined and confined aquifers.
Types of Water Wells
Driven Wells
Driven wells consist of a series of pipes with a point and a perforated pipe at the end. The point is driven into the ground, thus the name driven, to a depth of up to 75 feet.
Drilled Wells
Drilled wells can access water from a much deeper level by mechanical drilling. Drilled wells with electric pumps are currently used throughout the world, mainly in developing and developed countries, typically in rural or sparsely populated areas, though many urban areas are supplied partly by Municipal wells. Drilled wells are typically created using either top-head rotary style, table rotary, or cable tool drilling machines, all of which use drilling stems that are turned to create a cutting action in the formation, hence the term 'drilling'. Most shallow well drilling machines are mounted on
large trucks, trailers, or tracked vehicle carriages. Water wells typically range from 20 to 600 feet, but in some areas can go deeper than 3,000 feet.
Below are common well water contaminants and their associated treatment solutions.
Ferrous & Ferric Iron
Iron is one of the most common elements found in nature. It is understandable, therefore, that just about all water supplies contain some measurable amount of iron. In nature, iron usually occurs as an insoluble oxide. Under certain conditions, the iron is converted to a
soluble form and becomes dissolved in water with which it comes in contact. For that reason, iron can be found in almost every natural source but particularly in well waters. Well waters are usually high in carbon dioxide and low in dissolved oxygen and the insoluble iron oxide is converted to the soluble form of ferrous bicarbonate. Ferrous iron is colorless in solution but when it comes in contact with air, it oxidizes readily creating red, solid particles (ferric iron) staining whatever it comes in contact with. In addition, iron will impart a metallic taste to drinking water. Where total
iron is 0.3 ppm (mg/l) it can cause brown/red stains.
Product Solutions for this Contaminant
Pyrolox Filter System
Birm Filter System
Iron Filter + Softener System (sodium or potassium regeneration)
Iron Bacteria
Even at very low levels, iron can produce favorable conditions for the growth of what are known as iron bacteria. These organisms (Galionella and Crenothrix) utilize energy obtained from the oxidation of ferrous iron to ferric iron for their existence. The growth of these organisms will result in a jelly-like mass, cause pipe incrustation, and can produce foul tasting water. If the interior of a water closet has a gelatinous sludge and the water surface reflects a "rainbow" slick, it is usually a tell-tale sign of the presence of iron bacteria.
Because of the organic nature of iron bacteria, it is the most difficult iron to remove or control. Iron bacteria must be killed by
chlorinating - filtration alone doesn't eliminate them. The usual method is through chlorinating. High levels of chlorine are introduced into the plumbing and allowed to flow throughout the home to kill all all the bacteria. Superchlorination of the plumbing, toilets, pressure tank, and water heater may relieve the problem. Depending on the severity of the problem, often chlorine must be fed continuously to prevent future growth.
Product Solutions for this Contaminant
Pyrolox Filter System + Chlorine Feed System
Colloidal Iron
Iron colloids are insoluble in water and remain suspended meaning that they will not settle out so that they can be easily filtered from the water supply. Colloidal iron looks more like a colored water because the particles are so small that they cannot be seen. When water comes in contact with iron-bearing rock in the presence of decaying vegetation, conditions for forming this kind of iron exist. Colloidal iron may be present in shallow wells or surface water supplies. It is seldom found in deep well supplies. Like other forms of iron, colloidal iron causes reddish-brown stains. Whenever iron is oxidized from the soluble state to the precipitated state, the particles first formed are molecular in size. These particles agglomerate to form larger clumps, which may become large enough to settle, or they may stop growing when they reach colloidal size.
In the presence of decaying vegetation, the tiny particles may combine with the organic matter. When this happens, the organic matter causes the particles to have a static electrical charge and they repel each other. Since the particles repel each other, they cannot floc together to form larger particles. In the absence of organic matter, the particles will floc together and grow in size. Soon the particle floc becomes large enough to settle out of suspension. At this point the oxidized iron is no longer colloidal and can be removed by ordinary filtration. The most practical solution to the colloidal iron problem is to feed chlorine into the water. Chlorine will oxidize the substance to which the iron is bound
and so allow the iron to be removed.
Product Solutions for this Contaminant
Pyrolox Filter System + Chlorine Feed System
Manganese
Manganese is rarely found alone in a water source but is generally found in conjunction with dissolved iron. Concentrations as low as 0.1 ppm are considered troublesome. Deposits of manganese will collect in plumbing systems and the tap water drawn will display a blackish turbidity. As compared to iron, manganese will oxidize more slowly and in effect will require more oxygen to precipitate. Manganese reduction and removal is commonly accomplished by the same techniques as applied to iron removal.
Product Solutions for this Contaminant
Birm Filter System
Pyrolox Filter System
Hydrogen Sulfide
Hydrogen Sulfide (H2S) is a gas possessing an offensive odor commonly referred to as "rotten egg" odor. Deep and shallow well waters
containing this objectionable contaminant are known as "sulfur water". Hydrogen Sulfide gas is flammable and poisonous in high concentrations. In addition, it is corrosive to most metals. As little as 0.5 ppm of Hydrogen Sulfide concentration is odor detectable by most people.
Product Solutions for this Contaminant
Birm Filter System
Pyrolox Filter System
H2S Filter System
Chlorine Feed System (may be needed in addition to above choices for difficult applications)
Hardness
Hard water is common problem. Water in 85% of the United States is considered very hard (10 grains per gallon or more). There are only a few areas in the United States where ground water is considered to low in water hardness. No natural water supply is completely from water hardness. Any water with a water hardness greater than 7 grains per gallon is considered hard water. Why does hard water constitute such a problem. Water hardness is source of many problems. One important trouble area is the way hardness minerals react with soaps and detergents. This hardness problem is sometimes identified as "soap curd" Water hardness is comprised of calcium (primarily) and magnesium. Water hardness makes cleaning much more difficult. In the laundry, hard water leaves soap curd and detergents deposit on fabrics. This dulls colors and gives a grey or yellow appearance to white fabrics. Also hard water soap curd clings to fabric fibers, causing threads to become brittle and shortens the life of fabrics. Hard water wastes soap and other cleaning products in the home. Hard water leaves unsightly soap scum rings in the bathtub and toilets. Hard water spots glassware and dishware. Hard water also builds up scale deposits in all water using appliances and restricts household piping. Hard water scale also can sharply reduce the heating efficiency of a boiler or water heater resulting in higher energy bills.
Product Solutions for this Contaminant
Iron Filter + Softener System (sodium or potassium regeneration)
Organic Compounds
Water supplies can contain dissolved organic compounds (some of which are chemical contaminants) whcich are usually pollutants that enter the water as a result of man's activities, such as insecticides, pesticides and herbicides. These contaminants are chronically toxic to humans and other species in extremely in small amounts. Some organic compounds are THMs, TCEs, PCBs, Dioxin, etc. Many of the organic compounds are associated with dangerous carcinogens (cancer producing contaminants).
Product Solutions for this Contaminant
Activated Carbon Filter System
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