The best way to check if the septic system is up to code is to call the local authority having jurisdiction. This person or body will inspect what you have and let you know. Having said that, this person is likely to force you to upgrade the system if it is deficient and not close to todays’ minimum standards. There are some systems that are grandfathered but no system must be grandfathered. The inspector has the power to make you replace the system so be aware of that fact. A rule of thumb in this area is, if the system has a pump out you must have a minimum of 10 acres. You system must have a proper tank, not an old car cavity buried in the ground. If the water table is too high you most likely will need an at-ground system or a mound system. There is so much more so call with your specific details and yes we inspect and design new and old systems. Unlike the municipal and public health inspectors, I have no authority to enforce changes. I merely suggest improvements.