Foundation heaving

[Roberto Andrade]

I'm under contract for a SFR in Round Rock TX for a Buy&Hold investment, year 1960,1200 sf, 3B/1Ba, Price: $110,000, Repairs: $5,000, Rent: $1,200. Today we did the foundation inspection and found the kitchen and laundry "heaving", the foundation tech. thinks this is most probably due to a leak in the sewer pipes, and he strongly recommends to do a plumbing test prior to move forward with the deal. The option period ends this Friday and I have the Home Inspection scheduled for Thursday. We contacted the Seller's agent to let them know about the issue and that we want the plumbing to be tested in order to continue.

Any recommendations on how to proceed in this case?
Should I cancel the Home Inspection until the plumbing test is performed (in order to save that cost)?