If your tank water heater has started making a popping or rumbling sound — like popcorn in a steel drum — that is not a ghost and it is not the burner. It is sediment: dissolved minerals out of Lake Michigan water that settle and harden on the bottom of the tank over the years.
Here is what is actually happening. Water gets trapped under the sediment layer, the burner superheats it, and steam bubbles violently force their way up through the scale. Each pop is a little steam explosion. Beyond the noise, the sediment blanket forces the burner to run longer to heat the same water, which is why an older, scaled-up tank quietly adds 10–20% to a gas bill.
Can it be fixed?
Sometimes. If the tank is under roughly eight years old, a proper flush — drained under pressure until the discharge runs clear — removes most loose sediment and usually quiets the noise. We do this as part of every water heater service call, and it is the cheapest thing you can do to extend the life of a tank.
If the tank is past ten years, heavily scaled, or showing rust at the drain valve or in the hot water itself, flushing is usually throwing good money after bad. The popping by then often means the scale has fused to the bottom, and the repeated overheating cycles fatigue the steel and the glass lining. The next stage is a slow leak from the bottom seam — and tanks do not warn you politely when that happens.
The honest math
A flush and tune-up runs well under $200. A new 40-gallon tank installed is $900–$1,500. A flooded utility room is whatever your deductible is, plus weeks of disruption. Our rule, the same one we give family: noisy and under 8 years old, flush it; noisy and over 10, plan the replacement on your schedule instead of the tank’s.
And if you are replacing anyway, that is the moment to weigh tankless. In Chicago two-flats with tight mechanical rooms, an on-demand unit frees real floor space and shrugs off the sediment problem entirely.