How is the daily design sanitary sewage flow for a residential occupancy calculated?

• A. From Table 8.2.1.3.A.
• B. From a fixed per-capita value
• C. From the soil percolation rate
• D. From the building footprint

Answer: (A)

The main idea is that daily design sanitary sewage flow for a residential occupancy is taken from a published design flow table that links occupancy type to expected wastewater generation. This table provides a realistic, standardized value you use to size the septic tank and the leach field, rather than guessing or using a single fixed value. It accounts for typical usage patterns, which can vary with the number of occupants and dwelling characteristics, giving a more accurate design than a blanket per-person figure.

Why this is the best approach: using a table like this aligns with established design practices and codes, ensuring consistency and safety in system sizing. It reflects real-world water usage more accurately than a fixed per-capita value, and it specifically targets the amount of wastewater entering the system, not how the soil or the footprint of the building might influence other aspects of design.

The other options don’t fit because soil percolation rate affects how the effluent disperses in the soil (the absorption area), not the total daily wastewater volume; the building footprint doesn’t determine how much wastewater is generated; and a fixed per-capita value ignores variations in occupancy patterns and fixture use that the table captures.