Welcome to Just Answer. I will do my best to fully answer your question(s).
Try Root- X. There are likely other sources to purchase. Maybe even lowes or home depot but not certain. No need to hire a plumber. Put in toilet and/ or clean out.
I see you viewd my answer to your question but did not respond or ACCEPT. Do you have any other questions I cana help you with today? Please let me know.
septic system is for rural drian systems with no municipal "sewer system available. If you have city water that you pay for most likley your sewer is connected to thier system as well.