Different Types of Water Heater Sediment — What They Mean

Published: July 20, 2026 — CANRO Heating & Cooling — Greater Vancouver, BC

White/Grey Sediment

White or light grey sediment is calcium carbonate (limescale) from hard water. It is the most common type in Vancouver municipal water. It settles at the bottom of the tank and insulates the burner, reducing efficiency. Annual flushing removes it effectively.

Brown/Red Sediment

Brown or red sediment is iron oxide (rust) from the tank or pipes. If only the water heater produces rust-coloured water, the tank is corroding internally and replacement is needed. If both hot and cold water are rusty, the source is the home plumbing, not the water heater.

Black Sediment

Black sediment is usually manganese or magnesium oxide, or in some cases deteriorated anode rod material. Black sediment is common when the anode rod is aluminum-based and the water chemistry reacts with it. Flushing and replacing the anode rod with a magnesium type resolves the issue.

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Safety Reminder

If you smell gas, suspect carbon monoxide or believe there is an immediate danger, leave the property and contact emergency services or the appropriate gas emergency authority. Do not remain inside — exit the building immediately and call for help from outside.