About SepticSizeChart

SepticSizeChart is an independent planning tool for the roughly one in five American homes that run on a septic system. It exists because of a simple finding: the septic tank size charts copied around the internet don't match the state rulebooks they claim to summarize — in our first nine-state check, not one matched in full.

So this site does two things and shows its work on both: a size calculator that runs each state's actual rule (table, formula, flow or county system), and a cost estimator that assembles an installed price from published prices and fee schedules, line by line. Our method page explains exactly where every number comes from.

We are not installers, designers or a state agency, and nothing here replaces your county health department or a licensed local installer — state minimums are floors, and your soil has the final say. Contact: [email protected] — corrections with a source link are especially welcome.