Corrective Action for Water that Does Not Meet the Recommended Guidelines

If test results show an unacceptable level of total coliforms or E. coli, it is necessary to shock treat the well and, if possible, find and eliminate the source of contamination. Disinfection can be done using unscented household bleach. The table below outlines the quantity of bleach required to properly disinfect new and existing wells. If the source of contamination cannot be found and eliminated, the water should subsequently receive continuous disinfection.

* New wells require a chlorine concentration of 250 parts per million (ppm) for effective disinfection, whereas existing wells require 50 ppm chlorine.

1. Add the amount of unscented bleach determined in Table 1 to the bottom of the well and then agitate the water. Connect a garden hose to a nearby tap and wash down the inside wall of the well. This will ensure thorough mixing of the chlorine and the water throughout the well.

2. Start the pump and bleed air from the pressure tank. Open each tap and allow the water to run through all taps until a smell of chlorine is detected, then turn off the taps. If a strong smell is not detected, add more bleach to the well.

3. Allow the water to sit in the system for 12-24 hours.

4. Start the pump and run water through the outside hose away from grass and shrubbery until the strong smell of chlorine disappears. Make certain that the water does not enter any watercourse. Finally, open the indoor taps until the system is completely flushed.

5. Wait 48 hours, then sample the water using the instructions and bottle provided by the laboratory. In the meantime, find another source of water, or boil the water for one minute before drinking it. Two consecutive "safe" tests, performed on samples obtained over a period of one to three weeks, will probably indicate that the treatment has been effective.

6. If the shock treatment solves the problem, repeat bacteriological testing in three to four months.

7. If the above steps do not alleviate the problem, it is recommended that the source of the ongoing contamination be determined and corrected, possibly with professional help. If remediation is not possible, a permanent alternative solution, such as a new well or a drinking water disinfection device, should be considered.

The larger part of pathogenic microorganisms is removed from water during the primary water purification steps. However, water disinfection is still necessary in order to prevent drinking water from being harmful to our health.

Microorganisms

Microorganisms can be found commonly in nature. Invisible to bare eyes, microorganisms are present in soils, air, food and water. Before humans are born, we are free from microorganisms. Through consumption of food and air we are exposed to microorganisms soon after we are born. The microorganisms will remain present on and in our bodies. Most microorganisms are harmless and will contribute to a number of vital processes in the human body, such as the metabolism. But there are also microorganisms which can cause disease or which are harmful to people with low resistance to disease.

Pathogenic microorganisms in the water have a number of specific properties which distinguish them from chemical contaminants. They are living organisms. They are not dissolved in water, but they will coagulate or attach to colloids and solids in water.

Types of pathogenic microorganisms

Pathogenic microorganisms in drinking water can be divided up into three types: bacteria, viruses and parasitic protozoa. Bacteria and viruses can exist in both surface water and groundwater, whereas parasitic protozoa can be found mainly in surface water.

Bacteria
Bacteria are single-cell organisms, shaped like a sphere, spiral or rod. They can exist as individual bacteria or in bacterial chains, bundles or pairs. Bacteria are the most abundant life form on earth. They are between 0,4 and 14 μm in length and about 0,2 to 12 μm in width. Consequentially they can only be viewed under a microscope. Bacteria feed on fluid nutrients. They can reproduce by means of DNA replication, causing bacteria to split into two independent cells. In ideal circumstances this process takes about 15 to 30 minutes.

Some types of bacteria can form spores. These spores contain a protective layer which is heat resistant and can protect bacteria from a lack of moist and food. Bacteria play a role in various processes. Some bacteria break down organic matter and play an important ecological role, other assist in the human metabolism.

Viruses
Viruses are organisms which can cause infections and which only reproduce in living host cells. When viruses exist outside host cells, they are inactive. Viruses contain a protective shell. They are shaped like a spear, sphere or wire and they are so small (between 0,02 and 0,09 μm) that they can slip through filters which capture bacteria.

Contrary to bacteria and parasitic protozoa, viruses contain only one type of nucleic acid (RNA or DNA). They cannot reproduce, but instead take over the metabolism of the host cell and make sure the DNA is copied in the host cell, causing new viruses to develop.

Contrary to bacteria, viruses are not naturally present in the human body. When people are infected with a virus it usually leaves the body through secretion. When secretion takes place water can be contaminated with viruses. When the water is not thoroughly disinfected, other people can be infected with viruses.

Parasitic protozoa
Parasitic protozoa are single-cell organisms. They have a very complex metabolism and feed on solid nutrients, algae and bacteria which are present in multiple-cell organisms, such as humans and animals. Multiplication takes place through splitting of the cells. Various types of parasitic protozoa are spread in sleeping, protected form as a cyste or oocyste. Oocysts of Cryptosporidium and cysts of Giardia can be found in waters throughout the world as a consequence of fecal pollution. As cysts the pathogens are resistant to chlorine disinfection. Parasitic protozoa can be removed by means of filtration or chlorine dioxide application.

The odds of infection

The odds of infection depend upon the type of pathogen, the way in which it is transferred, the infective dose and persistence of the microorganism, and the resistance of the person that is infected.

The infective dose means the number of microorganisms that need to enter the body before the disease occurs. This dose is very low for viruses and parasitic protozoa. The persistence of a microorganism depends upon the viable time of the microorganism, when it is not present in a human host. Bacteria are commonly the least persistent microorganisms, and protozoic cysts are the most persistent ones.

Young children, elderly people and sick people have a lower resistance to disease and are therefore more fragile. When a person is infected the pathogens multiply within the host, causing the risk of illness to rise. Not every person that is infected with a pathogen falls ill. People that do become ill will spread a disease easily, mainly through secretion.

Secretion and sewer water

When water flows through a certain area, it collects all kinds of substances and gives these off in other areas. Microorganisms also enter the water. The larger parts of microorganisms which cause waterborne diseases originate from human or animal feces.

One drop of feces contains millions of microorganisms. In the feces of cattle there can be millions of E. Coli bacteria, Giardia cysts and Cryptosprodium spores. In chicken feces pathogenic bacteria such as Salmonella and Campylobacter can be present. When fertilizers are applied to land, rain can cause bacteria to rinse out the surface water or groundwater, causing the microorganisms to contaminate water.

Sewer or waste water cannot be discharged into the environment untreated. The larger part of purified waste water ends up in rivers, lakes and oceans. Sometimes heavy rainfall can cause sewer systems to flood, causing untreated water to end up in surface water or groundwater. Not every country purifies water before it enters surface or groundwater. Mainly developing countries lack sanitary facilities. The water can contaminate water that is used for drinking water purposes, causing the risk of infection with diseases carried by waterbone microorganisms to become very high. this is a particular risk when drinking water is not treated at all. When septic tanks are used for waste water treatment, pathogenic microorganisms can contaminate surface water and groundwater sources.

Not all pathogenic microorganisms in water originate from feces. Legionella can be found commonly in water and easily multiplies in the water distribution system. There are also other pathogenic microorganisms that can be found commonly in surface water.

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What is ultraviolet (UV) light?

Ultraviolet light exists at the invisible, violet end of the light spectrum. Although we can't see UV light, we are exposed to a small amount every time we walk out into the sun. The water treatment industry uses special lamps that emit UV light of a particular wavelength in order to disinfect water.

How does UV work?

UV rays penetrate into bacteria and viruses and destroy their ability to function and reproduce. The process is simple but effective: our systems destroy 99.99 per cent of harmful microorganisms without adding chemicals or changing your water's taste or odour.

Why not use chlorine?

Many people object to the taste and smell of chlorinated water. But more importantly, chlorine reacts with certain compounds that may be present in the water supply, resulting in by-products that have been linked to cancer (such as trihalomethanes, or THMs). UV light does not produce harmful chemicals in drinking water. It's safe, effective, and environmentally friendly.

Is pre-treatment of my water required for a UV system to work?

A 5-micron sediment filter should be installed upstream of any UV system so as to eliminate any particles large enough to block the UV light. The UV system should always be installed downstream of any other water treatment equipment. Ultimately, the quality of your water will determine if additional pre-treatment is required. Ask your dealer about TrojanUV's free water-testing service for hardness, iron, and UV transmittance.

• Chemicals such as iron and calcium carbonate can form deposits on the UV lamp's protective sleeve, reducing the light that can penetrate the water. Water softeners and iron removal systems are sometimes required.
• Chemicals such as iron, tannins and humic acid are able to absorb UV light and thus reduce the amount available for disinfection. After performing a simple test to measure your water's UV transmittance, your water treatment specialist can recommend treatment devices to suit your water supply.

How do I know what size of UV unit to buy?

You can treat the water for your whole home or just the drinking water from one tap. If you draw on a private water supply, it is recommended that you treat the water for your entire home. To determine the size of system you require, try our Model Selector.

Does a UV system consume a lot of energy?

No, a UV system able to treat the water for a typical house will consume about the same amount of energy as a 60-watt light bulb. UV is a cost-effective, natural way to increase water quality.

How often would I have to change the UV lamp?

It is essential that you change the UV lamp once a year. UV lamps, like light bulbs, will dim with age and eventually burn out. Trojan designs its UV units to generate the necessary UV light intensity at the end of one year's continuous use. The lamp will continue to burn long after, but it will not generate an adequate amount of UV light.

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