Does boiling lake water kill Giardia, other bacteria, and viruses? How long should it be boiled if we want to drink it? Should it then be stored in the fridge?
—Vicki McCudden, the Kawarthas, Ont.

A rolling boil for at least one minute does kill Cryptosporidium, Giardia, viruses, and bacteria. Once the water’s boiled, allow it to cool, put it in a clean container and, yes, store it in the fridge. To be safe, you should also boil the water you use in recipes, to wash dishes or food, mix with juice or baby formula, make ice, or brush your teeth.

Of course, boiling won’t remove odour, a funny taste, or silt or sediment from the water. It also won’t get rid of heavy metals, pesticides, herbicides, or pharmaceuticals. Plus, it uses energy, and it’s not practical or efficient: Unless your cottage is equipped with an industrial cooking pot, or a 13th-century cauldron, you can probably only boil a few litres of water at a time. Bottom line? A purification system might be a wiser choice.