Myth No.1: my parents never pumped their septic in 37 years and it still worked fine. Why do I need to pump it every 3 years?
Fact. - you may not even know you have a problem with your system?
Have you ever had a camera in the outlet pipe to see how it's draining?
Your entire septic system could be saturated and you don't even know it. A malfunctioning system means the effluent isn't being treated or purified properly. Simply stated, the waste is likely going into the ground and soil on your property untreated.
It is recommended that your tank be pumped every 3 years for a reason. Stick to a schedule based upon the household occupants and the usage. A home with 4 occupants would have a different pumping interval than a home with 2 occupants. Use your best judgement. 3-5 years is the standard in tank cleaning.