We are the original owners of a 4BR/2.5 Bath home that has been mainly occupied by 2 people over 14 years. (Occasionally 3 people for short periods of time, less than 1 year)
We have never had the cover dug/removed for the system / tank to be pumped.
I've gone by the "old school ecology" premise that if it is breaking down the intake effectively you should "leave it alone". Once you start pumping regularly, you have disrupted an effective ecological working system.
Is this a misnomer and a "plumber's tale" or should I subscribe to the "pumpers tale" of thinking?