Could there be money do to a renter for living and paying rent every month and dealing with leakiy septic?

Landlord-tenant laws are different in every state. In some, there would be money due to the renter, if verbal and written requests made to the landlord to repair the leaky septic [tank?] were ignored, and the renter wound up having to pay for the repairs himself/herself.

The renter then has the burden of proof (i.e., has to produce evidence such as photos of the leaky Plumbing, receipts for repairs done, including costs for parts and labor), production of eyewitnesses to the problem, and copies of letters to landlord, etc., if he/she plans to file a Small Claims lawsuit against the landlord to collect the money. If the renter wins in such a case, the court would allow him/her to include the court and process-of-service costs (postage and fees of delivery of court papers to the landlord by the Sheriff's Department, courier service or registered/certified mail), attorney costs, etc.

You can contact your local housing authority, or a landlord-tenant lawyer for advice on how to proceed for such a situation.