Nitrates reduce the ability of the blood to carry oxygen. In severe cases this can cause babies to turn blue. Immediate medical attention is necessary, because this serious condition can become fatal for these infants. Nitrate levels in well water tend to be highest in heavily-farmed areas. Fertilizer applications and animal manure are the principal sources of nitrates, which sink down into the water table from which well water is taken.
Septic tanks can also increase nitrate levels.
What you can do Since infants are most at risk, breast-feed your child if at all possible. Never give your baby well water, or mix infant feeding formula with well water that hasn't first been tested safe for nitrate levels. And most counter-top filtration units will not screen out nitrates. How to get your water tested Your local Environmental Health Officer or Public Health Nurse at Regional Health Units can tell you which areas are likely to be at risk for nitrate groundwater contamination. If you decide that your well water needs to be tested for nitrates, you can have a detailed analysis of your drinking water carried out by a private laboratory.