How is the size of a pumped effluent drainfield calculated?

The size of a pumped effluent drainfield is correctly calculated based on the number of bedrooms in a residence. This method takes into account the expected volume of wastewater generated by the occupants, as more bedrooms typically indicate a larger number of residents and, consequently, more daily wastewater production. The design standard assigns a specific flow rate per bedroom, which helps to estimate the necessary size of the drainfield to adequately treat and disperse the effluent.

Utilizing the number of bedrooms as a basis for calculation also aligns with health and safety regulations, ensuring that the drainfield is adequately sized to prevent overloading and potential system failure. This approach supports the proper function of the On-Site Sewage Facility (OSSF), preventing contamination of groundwater and ensuring sufficient treatment of wastewater.

While the size of the house may factor into overall plumbing design and systems placement, it does not provide a direct measurement of wastewater flow as effectively as the number of bedrooms does. Similarly, the age of occupants and type of wastewater may influence system design in specific scenarios but are not standard criteria for calculating drainfield size.