Contaminates That Dissolve:
The effects of repeated exposure to contaminates that dissolve such as, water-soluble pesticides, road salt, manure, mineral fertilizer, paints and glue products are unknown. Health problems may result after many years of exposure.
Contaminates That Do Not Dissolve:
Substances such as diesel fuel, gasoline, paint thinner, oil and common degreasers do not mix with water, although small amounts may dissolve making the water unsafe to drink. It only takes a litre of gasoline to make a million litres of water undrinkable because of the toxic chemicals contained in the gas. Chemical Contaminants table
Biological Contaminants:
Bacteria, viruses and other disease-causing organisms may contaminate water supplies. Total coli forms are found in animal wastes, sewage, soil and on vegetation. Fecal coliform bacteria are found in the excrement of humans and warm-blooded animals. Fecal coliforms tend to die rapidly outside the body; therefore, their presence in water indicates a relatively recent contamination. The presence of fecal coliform bacteria is representative of sewage contamination and is of greater concern because the risk of disease-causing agents also being present in the water is much higher. Water containing fecal coliform bacteria is considered unsafe for human consumption. Biological Contaminants table
| Back to Top |Point-Source Pollution
Point-source pollution is the wastes that are dumped by factories or sewage plants, for example. This type of pollution is relatively easy to monitor and regulate.
Nonpoint-Source Pollution
Nonpoint-source pollution or run-off is a larger problem. Polluted runoff is what happens when you spill oil on the driveway, then hose it down. It happens when a soybean field is treated with a herbicide, and then it rains. It happens when someone throws a dead battery into a gully. It happens when someone cleans a car part with solvent and dumps the liquid on the ground. It happens when a gardener sprays a lawn with fertilizer. Water picks it all up - oil, manure, lead, nitrogen, phosphorus - and adds it to the water system. Most people do not realize that most water pollution is from runoff.
| Back to Top |E. Coli is the short form of the name of the bacteria in the family Enterobacteriaceae named Escherichia coli. These bacteria are found in our intestines and makes up approximately 0.1% of the total bacteria found there.
The presence of E.Coli and other kinds of bacteria are necessary in our intestines so they can help us digest our food and keep us healthy. We depend on E. Coli to make vitamins K and B-complex vitamins which we then absorb. There are billions of these bacteria in our intestines, so why are E. Coli sometimes considered harmful? Just as there are billions of people on the earth and most of them are good, there are a few individuals that are not very nice - and we know that some can be downright dangerous. So, as there are individual people so too can different individuals exist among E. Coli bacteria, and these different strains can be harmful to us. The rare strain of E. Coli 0157:H7 is an organism which causes hemorrhaging and therefore, loss of blood. Only ten of these bacteria are enough to be fatal to small children, the sick or elderly.
E. Coli bacteria are everywhere in the environment. But, since they are such a common occupant of all animals, anytime we eat something, drink something, or touch something that has been either a part of or has been near where animals are, there is always the potential to ingest these bacteria, the good along with the possibility of bad ones.
Normal intestinal bacteria such as E. Coli are easier to isolate and identify than other types of bacteria. Their presence in a water sample may indicate that pathogens, which are usually greatly outnumbered in water by normal intestinal bacteria, may be present. Pathogens are disease-causing microorganisms and if they were present in the water they could make us sick or even die. Water that tests positive for E. Coli bacteria is always considered unsafe for human consumption as a precaution.
| Back to Top |Water samples sent to a laboratory are tested for indicator organisms, rather than pathogens, which are the actual disease causing microorganisms. The coliform group of bacteria is the principal indicator as to whether the water is potentially unsafe. Determination as to whether bacteria are considered fecal coliform or total coliform gives valuable information concerning the possible source of the contamination. Non-fecal coliform survive longer in water than fecal forms, therefore the presence of fecal coliform indicates a recent contamination and the greater possibility of other disease causing pathogens being present in that water.
There are several test methods to determine the presence of coliform bacteria. Two of the standard ones are the Membrane Filtration Technique and the Multiple-tube Fermentation Test. The filtration technique is considered more precise. The results of a test are given as a Most Probable Number index or MPN or as a membrane filter count per 100 ml. Because it is not necessary to provide a quantitative assessment of coliform bacteria for all samples, a qualitative presence/absence procedure is sufficient.
With the Membrane Filtration Technique the water sample is passed through a membrane, which is specially designed to filter out things like bacteria. The filter is then placed on a suitable medium. A medium is a food source especially suited for the growth of coliform; one of the ingredients of this medium is lactose, a form of sugar. The plate is then incubated for 24 hours at 44.5ºC for E. Coli or 35ºC for total coliform. E. Coli will produce a gas under these conditions, other coliforms will not. If a gas is detected, the water sample is considered to contain E. Coli and is labeled unsafe for human consumption.
There are other tests that can be performed on the bacteria colonies that have grown during the incubation process to identify the specific number and type of bacteria. These tests however, do not change the fact that the water is unsafe to drink but may help to identify the type and source of contamination.
| Back to Top |It is estimated that more than ten million people die each year around the world from water borne diseases such as typhoid fever, cholera, enterovirus disease, bacillary and amoebic dysenteries, and many varieties of gastrointestinal diseases.
The treatment of a water supply for the purpose of destroying bacteria and viruses is known as disinfection.
The following is a listing of some of the current methods available.
Ceramic Filter
Ceramic filters may be used to filter raw water, but may not be effective with high concentrations of bacteria. Ceramic filters should not be used as the only method of disinfection.
Ultraviolet light
Contaminated water can be treated by passing it over an ultraviolet tube. The rays emitted by the tube kill bacteria, providing there is sufficient contact time. Ultraviolet light is not effective on water highly contaminated with coli form and should not be used as the only source of disinfection. The output of the lamp decreases with age and needs to be checked regularly.
Iodination
This is a slow method of disinfection, as it requires a long contact time. It is recommended that a charcoal filter be used after the iodination process to filter out any remaining iodine, as it may be a health hazard causing adverse effects to the thyroid in humans.
Chlorination
Despite public health and safety concerns associated with chlorine, it remains the predominant disinfection method. Chlorine requires a 20-minute contact time to be effective. It is recommended that a charcoal filter be used after chlorination to remove any residual chlorine. When chlorine reacts with organic material it produces a substance called trihalomethanes, which is suspected of causing bladder cancer, colon cancer, and possibly be a factor in stillbirths.
Ozonation
The advantage of Ozonation is that it does not form chlorinated byproducts. Ozone is an unstable form of oxygen and has a strong odor like chlorine. It is a powerful oxidizing agent that is used for such things as; bleaching oils, waxes, flour and starch and for sterilizing drinking water. Ozonation is used extensively in municipal systems in Europe and is slowly gaining popularity in the United States and Canada.
Distillation
Distillation involves the heating of raw water and the condensation of the vapor to produce distilled water. This method’s major drawback is its cost and the fact that it is a slow process yielding only small quantities at a time.
Boiling
This is a useful method for disinfecting small quantities. My experiment proved that boiling water for two minutes is not long enough. The Ontario Ministry of the Environment recommends three minutes minimum, but the Eastern Ontario Health Unit suggests five minutes.
Reverse Osmosis
In a reverse osmosis unit, the water is forced through a semi-permeable membrane. Reverse osmosis has the potential to remove bacteria and some pesticides depending on the membrane used. Care must be taken and the membrane checked on a regular basis to ensure no rips or holes that would allow unsafe water to mix into the pure water.
Project and web design by: Mark Brittain