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The water quality of your artesian wells

When it comes from a surface or tubular well (commonly called an “artesian well”) and is intended for human consumption, the water must be of good quality and meet the standards set out in the Quality Regulation. drinking water (Q-2, r.40). Indeed, under article 3 of this regulation, the owner must provide drinking water to his family and his visitors.

Although it may have a clear and limpid appearance and have no particular odor or flavor, the collected water may contain elements that may have adverse health effects, for example pathogenic microorganisms (bacteria, viruses or protozoa) and nitrate-nitrites.

Groundwater, which is generally of better quality than surface water (lake, river, stream) thanks to the filtering capacity of the soil, can be vulnerable to contamination and precautions must be taken to ensure a good quality water supply.

A contamination event can occur sporadically, and only water analysis can reveal it. Thus, the Ministry recommends that you have your water analyzed by an accredited laboratory.

Indicators microbiological of water…

The majority of pathogenic microorganisms (viruses, bacteria or protozoa that can cause disease) likely to be found in water come from human or animal waste. As it is technically impossible to analyze all pathogens, microbiological indicators are used instead, which are harmless in themselves: E. coli bacteria, enterococci bacteria and total coliform bacteria.

E. colis bacteria are very abundant in the intestinal flora of humans and animals, and it is also the only species that is strictly of faecal origin. E. coli bacteria are considered the best indicator of fecal contamination. Their presence in the water means that the latter is contaminated by pollution of faecal origin and that it may therefore contain pathogenic microorganisms.

Gastroenteritis is the most common illness associated with ingesting water contaminated with feces. Although this disease is often mild, it can sometimes have very serious health consequences. Other rarer diseases such as hepatitis or meningitis can also be caused by ingesting contaminated water. This risk concerns not only the members of a family who consume water from a well, but also all their visitors.

Enterococci bacteria are less abundant in the intestinal flora of humans and animals than E. coli bacteria, and some species in this group are not of fecal origin. Detection of enterococci bacteria in well water may indicate faecal contamination or surface water infiltration. However, it is prudent to consider the presence of enterococci bacteria as an indication of faecal contamination.

Total coliforms are a heterogeneous group of bacteria of faecal and environmental origin. Indeed, most species of total coliforms can be found naturally in soil and vegetation. Their presence in the water does not indicate faecal contamination or a health risk, but rather a deterioration in the bacterial quality of the water. This degradation can be attributed, among other things, to surface water infiltration in the well, or to the gradual development of a layer of bacteria on the walls called “biofilm”. The analysis of total coliforms makes it possible in particular to obtain information on the possible vulnerability of a well to surface pollution.

Presence of bacteria E. coli or enterococci in my water what to do

Drinking water should not contain any traces of E. coli or enterococci bacteria. If this is the case, it is essential to keep this water boiling for at least one minute before consuming it, or to obtain drinking water from a distribution network or bottled water. Boiled water or water from these alternative sources should also be used for making ice cubes, beverages and baby food, washing food that will be eaten raw and brushing teeth. You can continue to use well water for showering and bathing (taking care to avoid swallowing it), however, children and babies should be washed with a sponge. These recommendations must be followed until subsequent analyzes reveal that the water meets the standards.

It is recommended to determine the source of the contamination and to take the appropriate corrective measures, if possible. Then, a shock disinfection treatment of the well may be appropriate, especially when the contamination is linked to particular circumstances (melt, heavy rain, etc.). As a shock treatment can damage water treatment equipment, it is recommended to unplug yours, if applicable, before starting the procedure.

The disinfection of a well is carried out as follows:

  1. Clean the well, if possible, using a scoop to remove foreign bodies, deposits, animal or vegetable matter, etc.

  2. Pour bleach into the well according to the quantities mentioned in the following table, entitled «Required amount of bleach for disinfection of a well.».

  3. Mix bleach with well water and, if possible, wash and brush the inside wall. One can also connect a garden hose to the nearest tap and flush the inside wall of the well, to ensure thorough mixing of chlorine and water throughout the well.

  4. Open all cold water faucets in the residence. When the smell of chlorine is perceptible at the taps, stop the well pump and close the taps.

  5. Wait 24 hours before running water through the pipes. However, it is not necessary to purge your water heater.

  6. Then carry out a prolonged purge by letting water run from a faucet until the smell of chlorine disappears. Then open all the taps to completely flush the piping.

  7. Carry out new analyzes of the water one week after disinfection and four weeks later, in order to know if the water meets the quality standards.

Presence of total coliforms  in my water

The presence of total coliforms reinforces the importance of performing regular analyzes and taking the appropriate corrective measures to prevent any possible fecal contamination. If new analyzes confirm the presence of total coliforms in concentrations exceeding the standard (above 10 cfu/100 ml), it may be appropriate to carry out a shock disinfection treatment of the well.

Determine the source of contamination

It is important to determine the source of the contamination and to take the appropriate corrective measures to improve the quality of the water in the long term. The local sources of contamination can be multiple:

  • Poor layout of the well (lack of tightness of the cover or sealing, degradation of materials, etc.);
  • Inadequate slope of the surrounding soil (lack of a mound around the well to direct runoff from the surface away);
  • Faulty septic system;
  • Unsanitary conditions (e.g. manure spreading or other activities generating faecal pollution nearby).

In these cases, it is therefore a question of carrying out the work required to correct the situation or to make the person responsible for the source of contamination aware. Anyone struggling with a contamination problem can contact the municipal officer concerned, who will help guide their search for solutions. Subsequent water quality analyzes will verify the effectiveness of the corrective measures taken.

The quality of my well water in situation flood

During a flood, the owners of an individual well must take special precautions, since such events generate significant risks for the quality of groundwater; it can be contaminated both by river water and by nearby septic systems. To prevent the risk of illnesses related to the consumption of contaminated water, the Department recommends the following measures to those affected:

  • During the flood: water from any well located in a flooded area must be considered undrinkable. Affected persons should obtain drinking water from an alternative source (for example, water from a public supply or bottled water), or boil for one minute any water intended for ingestion or preparation of uncooked food.

  • After the flood: after the final removal of the flood waters, the owner should first check the integrity of the equipment in his well and more particularly the electrical circuit. He should then wait a minimum of ten days before disinfecting the well according to the procedure described below, and ensure that the results of the two series of analyzes recommended thereafter are compliant before starting to consume the water again.

Quantity required bleach for the disinfection of a well

A concentration of 50 mg/L of free chlorine is recommended to ensure effective disinfection of an existing well (use a recently purchased 5% unscented bleach, available on the market). To disinfect a new well, the bleach volumes listed in the tables below must be multiplied by five, since a concentration of 250 mg/l of free chlorine is recommended.

This text comes from Ministry of the Environment and the Fight against Climate Change. To learn more about water testing and drinking water quality standards, visit: (french) http://www.environnement.gouv.qc.ca/eau/potable/depliant/index.htm. Consult the list of laboratories accredited to carry out a water analysis.