It’s a myth that septic tanks never need pumped. The sludge fills the tank letting excessive organic material into the drainfield. Between the sludge and overgrowth of biomat, the pipe and soil eventually becomes so clogged the water has nowhere to go. How long this takes depends on a lot of factors but soil porosity is a big one. This is why some systems go 50 yrs and others fail after 20. Just because the toilets flush doesn’t mean it hasn’t failed. A failed system is one that isn’t properly t