Sludge accumulation in a tank serving a normal home has been estimated at

The typical estimate for sludge accumulation in a tank serving a normal home is based on the amount of solids that settle in the septic tank as a result of sewage decomposition processes. The correct choice, which is 18 to 21 gallons per person per year, reflects standard measurements used in septic system maintenance and design.

This range is recognized as a common guideline for evaluating sludge production, which is critical for determining how frequently a septic tank should be pumped to maintain its performance and prevent overflow or system failure. Understanding this accumulation helps environmental health professionals assess the health of septic systems and advise homeowners accordingly. Regular monitoring and maintenance based on these estimates play a key role in ensuring the longevity of septic systems and protecting the surrounding environment from potential contamination.

The other provided options are outside the established ranges for domestic sludge accumulation and would not accurately reflect typical household septic system conditions.