Hydrogen Sulfide is a by-product of a sulfur-feeding bacteria and is noted by its distinct smell. Rotten egg, sulfur, and sewer gas are common descriptions. It is also accompanied by black slimy build up that can cause many of the same problems as iron bacteria.
Iron Bacteria is most noticeable by the slimy red coating it leaves in the water system. Severe cases can plug pumps and pipes, increase operating costs, and lead to premature pump failure. Low water pressure is a common symptom of severely plugged pumps and pipes. Water-conditioning equipment (softeners, filters) can become plugged easily, leading to frequent service calls and inconsistent operation. Stains on porcelain fixtures, (i.e. tubs, showers stalls, etc.) are common. On the farm, waterers can be coated with a red or black slime, which can discourage livestock from drinking and promote more bacteria growth.
Manganese is characterized by black to grayish deposits, or black water with a metallic taste. Chemically, its treatment is similar to iron. Manganese appears in the same forms and exhibits the same problems. While not as common as iron, it will show up at much lower levels: .05 ppm is enough to cause problems. Dissolved manganese is slower to oxidize than iron so early chlorination is helpful. Unlike iron, any build ups in pipes are difficult to remove, so ignoring the problem can lead to more expense in the future.
Coliform bacteria si the standard used in well testing. Coliform is present in many warm-blooded animals as a normal part of the digestive tract. Its presence in a water supply is an indication that animal or human waste is making its way into a water supply. Coliform bacteria has no detectable smell or taste. The coliform itself may not be a problem, but is an indicator that other pathogenic bacteria may be present. These bacteria can cause disease such as typhoid, cholera, hepatitis, giardiasis, and dysentery. Although these are common in many underdeveloped countries, the lack of these diseases in the United States is largely attributed to the chlorinated water supply.
Because chlorine is a sanitizer, it will kill these bacteria id applied properly. In laboratory conditions, chlorine at 1ppm residual takes 20 minutes contact time to achieve 100% kill of coliform bacteria. If the bacteria is exposed for less time or at lower levels, it may still be present when the water is consumed. By dropping dry pellets into the well, treatment is started at the earliest possible time, and in most cases, the 20-minute mark will be met. Testing is the only way to confirm the effectiveness of chlorination. If bacteria is still present, a higher level of chlorine or more retention time through the addition of holding tanks may be necessary.
Because 5% of the earth's crust is iron, it is no surprise that many wells contain it in various amounts. It takes just a trace of iron to cause problems: as little as .2ppm can stain plumbing, fixtures, and laundry. In larger amounts, water can become rust colored and have a metallic taste. Iron can coat the insides of pipes with hard, red scale, which reduces flow rates and plugs filter screens.
Because iron is found in different forms the treatment can vary.
Ferrous iron is dissolved and appears clear out of the tap. At lower levels, it can be removed by ion exchange (water softening), but if iron bleed through occurs(red stains, rusty water, etc.), it may have to be oxidized and filtered
Ferric iron is oxidized (precipitated) and appears red out of the tap. It consists of particles in the 30- to 50- micron range and will pass through most water softeners. An iron filter will probably be needed.
Heme iron is iron bound up with organic material (often referred to as tannins). It needs to be oxidized by chlorine to destroy the bond between the organic material and iron to precipitate the iron out of the solution.
Iron bacteria needs to be sanitized and the precipitated iron filtered.
Ferrous iron and iron bacteria occur most often.By pre treating with Dry Pellet Chlorination, the different types of iron can be converted to ferric which can be filtered. Adequate contact time is necessary, since the iron may not precipitate immediately, especially if it is bound up with tannins or iron bacteria. Generally, 30 minutes are thought to be sufficient. Over time, continuous chlorination will remove built up iron deposits from plumbing.
Shallow wells and water drawn from ponds may be contaminated with surface runoff and biological debris from both plants and animals. Ponds are particularly prone to this since they contain numerous forms of life that can be drawn easily into the pump. These contaminants can be filtered out physically, but the water should be sanitized for human or livestock consumption and for aesthetic and health reasons. Whether they are pathogenic or not can be determined only by a test, but these types of water sources are subject to many variables affecting their quality.
This water can be used for residential water supplies. Many cities use water from lakes, rivers, reservoirs, and shallow wells. But like in the cities, this water should be chlorinated and filtered.