Calculation & Generation Results
About This Tool
Calculate minimum septic tank capacity in gallons, daily wastewater effluent design flow (GPD), soil percolation rate absorption, and linear feet of gravel/chamber leach field trenches.
Frequently Asked Questions
How are septic tanks sized under US building codes?
Septic tanks are legally sized by the number of bedrooms in a home (typically 120 gallons per day per bedroom), not the number of bathrooms or current residents, to accommodate future maximum occupant capacity.
What is a soil percolation (perc) test?
A percolation test measures how fast water drains into subsoil (in minutes per inch). Fast-draining soils require smaller leach fields, while slow clay soils require substantially longer drainage trenches to prevent sewage surfacing.
What is the advantage of chamber systems over conventional gravel trenches?
Plastic leaching chambers (such as Infiltrator Water Technologies) eliminate crushed stone, provide 100% open bottom area for biomat respiration, and allow a 25% to 40% reduction in total drainfield footprint under most state health codes.
How often should a residential septic tank be pumped?
The EPA recommends having a septic tank pumped every 3 to 5 years by a licensed pumper to remove accumulated sludge and scum before it escapes into the drainfield and causes catastrophic soil clogging.