Generally, if you have a drilled well that is secure, intact and not subject to flooding, then an occasional bacterial count should first be confirmed with a resample, and if confirmed, should first be dealt with by shock chlorination (disinfection) of the well.
This will, in most cases, resolve the problem. You may, on occasion, have to repeat the chlorination if there are significant levels of iron in the water or if there is a biofilm buildup in the pipes. In exceptional circumstances, you may require a permanent treatment device.
If you have a dug well (whose joints are usually not sealed) or a sandpoint that draws from a shallow upper water table, then bacterial counts may show up from time to time and will most likely appear after a storm or during spring snow melt.
Shock chlorination may be effective temporarily but the next storm or heavy rainfall may produce another bacterial count. In these circumstances, a permanent treatment device should be considered if a long term solution is desired. Constant, repeated shock chlorination is not a solution.
A dug well might also be replaced with a drilled well that may not need any treatment devices. You could check with the Ministry of Environment's well records department or with neighbours who have drilled wells to see what quality and quantity of water is normally found in your area before deciding to drill.
If you draw from an unprotected source like a stream or lake or other open body of water, then the water supply is not safe and should not be used as a source of drinking water, unless it is adequately treated first.
Simple treatment systems may not render the water safe because the quality of the water may vary drastically from day to day and one needs to consider not only bacterial contamination but also viruses, parasites like cryptosporidium and giardia; and, in some areas, chemical contamination from water craft motors and runoff from land can make water unsafe.
Adequate treatment must be comprehensive, may be expensive, and will require maintenance.
TYPES OF WATER TREATMENT DEVICES
If your water is contaminated, it is better to remove the source of the contamination than to treat the water. But, if the problem cannot be solved at the source, a number of water treatment devices are available.
There are two types of water treatment devices. Ones which remove bacteria and ones which remove chemicals.
Bacterial Treatment Devices
Bacterial treatment devices can be broken into two groups:
- installed on taps
- installed on the main water supply entering the home
Chlorinators:
- need to continuously add chlorine to water
- chlorine kills most disease-causing organisms and requires contact time with water to do so, but chlorine does not provide protection against parasites
- chlorinators have to be checked often to ensure the right amount of chlorine is being added
Iodine:
- Iodine should be used for emergency use only and not for long-term use because ingestion in excessive amounts may be harmful.
Ultra Violet Light:
- effective against bacteria and viruses but requires filters to remove parasites and reduce turbidity
- system requires flushing after periods of non-use
- the light needs to be replaced regularly
- water needs to be refrigerated after treatment
Distillers:
- kill bacteria, viruses and parasites but require electric power to boil the water, then condense the vapour
- require space to install the equipment
Ozonators:
- produces ozone gas which is injected into water to kill most bacteria
- require a good mixing of ozone and water
- water should be refrigerated after treatment.
CHEMICAL TREATMENT DEVICES
Activated Carbon Filter:
- most common device used in the home (pitcher style, tap mounted, or under sink) using activated carbon filters
- are relatively inexpensive
- widely available and are promoted to improve taste and odour and remove organic chemicals.
- WARNING: bacteria can be trapped and multiply in a carbon filter – regular maintenance is required.
Reverse Osmosis:
- removes some chemicals but not bacteria – by passing pre-filtered water through a membrane.
EFFECTIVENESS OF DEVICES
While all are effective, no single device works for all. It is important that you take care when selecting, installing and maintaining a water treatment for your particular situation. And, it is very important to follow the manufacturer instructions with respect to routine maintenance such as regularly changing filters.