Septic Pump / Dose Tank Volume
Net dose per cycle, pumped volume per cycle and per day.
Example
You enter
- Design daily flow (gpd) 600
- Doses per day 4
- Drainback (gal) 5
You get
- Net dose per cycle 150 gal
- Pumped per cycle 155 gal
- Pumped per day 620 gal
- Dose-to-void ratio 30
Checked against published worked examples from: USEPA Onsite Wastewater Treatment Systems Manual / university extension LPP design...
Details, formula, and sources
ScopeNet dose per cycle, pumped volume per cycle and per day, and the dose-to-void ratio for a timed-dose pressure-distribution field. Per the USEPA Onsite Wastewater Treatment Systems Manual; the dose count and float settings on the permit drawing govern.
Formula or tableNet dose = daily flow / doses per day; pumped per cycle = net dose + drainback; pumped per day = pumped per cycle x doses; dose-to-void ratio = net dose / distribution-network volume (laterals + manifold; drainback only as a proxy when the network is not entered), target >= 5.
Source and editionUSEPA Onsite Wastewater Treatment Systems Manual (EPA/625/R-00/008); university onsite-wastewater extension low-pressure-pipe design guidance, by name.
Free accessFree at epa.gov/septic. Extension LPP design guidance free on land-grant university extension sites.
What governsEstimate. AHJ and licensed plumber / gas fitter govern. Verify against the IPC / IFGC edition adopted in your jurisdiction.
API field namesdaily_flow_gpd, doses_per_day, drainback_gal, net_dose_gal, pumped_per_dose, pumped_per_day, void_ratio
- Default doses per day 4 (editable; more, smaller doses rest the soil better)extension LPP design guidance
- Dose-to-void target net dose >= 5x the distribution-network volume (laterals plus manifold), not the drainback, so the field pressurizes before the dose is spentextension LPP design guidance
- Drainback handling drainback returns to the tank and is re-pumped (pumping energy, not lost flow); the dose count, dose volume, and float settings on the permit drawing governEPA/625/R-00/008