Water Heater Sediment Buildup — Prevention and Treatment
Published: July 12, 2026 — BC Wide Home Services Ltd, doing business as BC Wide Heating & Air Conditioning — Greater Vancouver, BC
How Sediment Gets Into Your Water Heater
Sediment enters your water heater through the municipal water supply. Greater Vancouver's water, while high quality, contains dissolved minerals including calcium and magnesium. As water is heated inside the tank, these minerals precipitate out of solution and settle at the bottom. Over months and years, the accumulated sediment forms a layer at the tank bottom that insulates the water from the burner, reducing heating efficiency and tank capacity. In areas with harder water, sediment buildup occurs faster.
Symptoms of Sediment Buildup
The most noticeable symptom is reduced hot water capacity — your hot water runs out faster than it used to. Sediment at the bottom of the tank reduces the volume of water the tank can hold and insulates the water from the burner flame or heating element. You may hear popping, crackling, or rumbling sounds when the burner fires. This is water trapped under the sediment layer boiling and bursting through the sediment. The tank may take longer to recover between uses. Your gas bill may increase as the burner runs longer to transfer the same amount of heat through the insulating sediment layer.
Annual Flushing — The Prevention You Should Be Doing
Flushing your water heater once per year removes accumulated sediment before it causes problems. For gas water heaters, set the gas control to PILOT. Connect a garden hose to the drain valve at the bottom of the tank and run the hose to a floor drain or outside. Open the drain valve and allow water to flow until it runs clear. For heavily sedimented tanks, the drain valve may clog — if water does not flow, professional service is needed to flush the tank without damaging the valve.
When Professional Descaling Is Needed
If the tank has not been flushed for several years, the sediment layer may be substantial. A standard garden-hose flush may not dislodge it. Professional descaling involves connecting a pump to circulate a descaling solution through the tank, dissolving accumulated mineral scale. This process can restore significant lost capacity and efficiency. If the tank is over 10 years old, weigh the cost of professional descaling against replacement — heavily scaled tanks may have internal corrosion beneath the scale layer that becomes evident once the scale is removed.
Anode Rod — Your Tank's Sacrificial Protection
Every tank water heater contains a sacrificial anode rod — a magnesium or aluminum rod that corrodes instead of the steel tank. The anode rod is the primary reason water heater tanks last 10-15 years rather than 2-3. It should be inspected annually and replaced when more than 50% consumed. A depleted anode rod means the tank itself is now corroding. Replacing the anode rod is the single most effective maintenance task for extending water heater life. Combined with annual flushing, anode rod replacement can extend tank life by 3-5 years.