Commercial property lease obligation?

[sasqua]

pennsylvania, relative has 3 commerical buldings( all next to each other), 1 has shops where she, herself has a store. 2 out buildings that are leased. one of the out buildings is a restaurant. They pay rent but have lately started to deduct the cost of cleaning out the septic tank, my aunt says they are pouring grease from the grease trap into the septic tank. they say she's responsible, and she's says they are. She also says the lease agreement says they're responsible.How can this be resolved?

 

[HomeGuru]

1. it is ilegal to put grease into a septic tank.
2. have aunt hire an attorney to review the lease and send the greasy tenant a letter of default.