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Well Water & Your Baby

This web page is for parents with babies and young children who use private wells as a source of drinking water. Private wells can become contaminated with bacteria, nitrate, or other chemicals. The effects of drinking contaminated water can range from no reaction to intestine illnesses (diarrhea) or even death. Parents should be familiar with their well water supplies. It is the well owner’s responsibility to take samples and inspect their well to ensure that their drinking water is safe.

What to look for when testing your well water


  • The 2007 Halton Well Water Study showed that up to 36% of all wells surveyed had an unacceptable level of total bacteria. This is an indicator that disease causing organisms could be present. A major cause of this contamination is poor well maintenance.
  • A bacterial test of your well water should be done 3 times per year (in spring, fall, and one other time).
  • Sample collection bottles are available from Halton Region Health Department at their water depot locations.
  • For infants less than 4 months of age, parents should bring all water to a rolling boil for at least 1 minute, cooling completely before serving or using the water.


  • Although a recent study in 2007 found that 100% of wells surveyed in Halton had acceptable nitrate levels, parents of infants should still have their well water tested.
  • Nitrate is a contaminant that comes from sewage pollution, natural mineral deposits and other types of fertilizers.
  • High levels of nitrate in a water supply could lead to a condition known as methaemoglobinaemia (blue baby syndrome). This condition robs the oxygen carrying capacity of the blood and causes a blue skin colour to infant babies up to the age of 3 - 6 months.
  • Although there is no conclusive evidence that high nitrates in drinking water affect other age ranges, it is best to keep a level of 10 mg/L or less for all consumers.
  • Well water should be tested yearly for nitrates to ensure that the level does not rise over time.
  • Nitrate is not removed by boiling water. It must be removed by a treatment device designed for that purpose.


  • Low levels of fluoride in drinking water help to reduce tooth decay. In some communities it is added to municipal water supplies.
  • To prevent decay, fluoride content in water should be between 0.5-to-0.8 mg/l.
  • Like many substances that are helpful at low levels, fluoride can be a problem at high levels.
    • Exposure to high levels of fluoride can cause dental fluorosis which in its mild form occurs as white spots on teeth.
    • In cases of moderate-to-severe dental fluorosis, pitting or mottling of teeth occurs.
    • Another possible effect of too much fluoride is a bone disease called skeletal fluorosis, which is first marked by osteosclerosis, an increase in density of the bones.
  • Well water with naturally occurring high fluorides have not been identified in Halton Region. However, parents of young children should have their well water tested to determine the fluoride level.
  • Municipal water supplies are monitored regularly to ensure the fluoride content is between 0.5-to-0.8 mg/l.

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