The taste, odour, and appearance of our drinking water may vary at difference times of the years, specifically spring - due to runoff, and late summer/early fall.
"our source water can experience elevated levels of geosmin, a harmless, naturally occurring compound, in the water in the late summer and early fall. This can produce a temporary, earthy or musty change to the taste and odour of your water, but it remains safe to drink and continues to meet all guidelines set by provincial and federal health standards."
A change in your water taste, odour or appearance does not mean it is unsafe to drink.
Visit the City of Calgary's website for more information.