They normally have to be pumped every four to seven years.
However if you do not flush wipes, feminine hygiene products or grease you can go over eleven years and your tank will be ok.
That is what the people who owned the house before us did.
We had the system pumped and the guy said that if they had just used the monthly enzymes treatment it would not have been necessary to pump it even then.
Yep. Wipes are hell on septic systems. Especially those with filters to strain the soup before it heads into the drain field.