Wisconsin Counties require every three years
I have a 1,500 gallon conventional with a drainage field out back - Basically a two acre sand box in WI
I pull the cement cover for the pumper , we clean the filter , and he pumps away complaining every time on how much toilet paper we use
I blame the wife of course
$150.00 every three years for inspection and pumping - Price has almost doubled in twenty years , just like everything else
And trust me , they will fine you if it’s not inspected , pumped and paperwork sent in to the county
So far so great , going on twenty five years since the house was built
Wow...really? $150? Last time I had mine pumped it was well over $300.