Septic LPP Squirt Head for a Target Orifice Flow
The squirt head (residual pressure) that produces a target per-orifice discharge in an LPP drainfield.
Example
You enter
- Target per-orifice discharge (gpm) 1.275
- Orifice diameter (in) 0.25
- Discharge coefficient 0.6
You get
- Required squirt head 3
- Squirt pressure 1.30 psi
Details, formula, and sources
h = ( Q / (19.63 Cd d^2) )^2, with squirt pressure = h x 0.433 psi/ft. A 0.25 in orifice at Cd 0.6 delivering 1.28 gpm needs about a 3.0 ft (1.3 psi) squirt head. Flags whether it lands in the LPP 2.5-5 ft band. This is the residual at the orifice; the pump TDH adds friction and lift. The permitted onsite design governs.
h_ft = ( per_orifice_gpm / (19.63 x Cd x d_in^2) )^2, the inverse of Q = 19.63 Cd d^2 sqrt(h); squirt pressure = h x 0.433 psi/ft.
Standard orifice-discharge equation, solved for the head; university onsite-wastewater extension low-pressure-pipe design guidance, by name.
Extension LPP design guidance free on land-grant university extension sites.
Estimate. AHJ and licensed plumber / gas fitter govern. Verify against the IPC / IFGC edition adopted in your jurisdiction.
Field names used by the API: per_orifice_gpm, orifice_dia_in, cd, squirt_ft, squirt_psi
- Discharge coefficient Cd 0.6 default (gives the 11.79 / 19.63x0.6 orifice coefficient); editableorifice-discharge equation
- Squirt height target roughly 2.5 to 5 ft (about 1 to 2 psi) for LPP, higher for mound or dripextension LPP design guidance
- Residual only the pump TDH adds friction, lift, and transport loss on top of this squirt headextension LPP design guidance