I need advice on solving a foundation issue

[Katie Neason]

I have a rehab and flip property under contract. Nice house in a good neighborhood. The issue/potential opportunity: the house clearly has a foundation issue. I am not afraid of foundation issues and have rehabbed houses with foundation issues in the past. This house has had a foundation issue in the past and appears to be recurring. What I want to do is determine the source of the issue and if it is economically feasible to fix. Previous inspections have shown the foundation issue appears to be from excessive water under the slab. A water pressure test was performed and did not reveal a leak. Additionally the water bills are not reflecting a leak. So....seems like the other 2 culprits could be a bad grading job forcing water back under the house or a sewage problem such as a crushed pipe, or maybe something else I have not thought of. Before I buy the house I want to know the issue. Who should I call and/or what tests can determine the source? Anyone out there encounter a similar issue? Any advice or direction is greatly appreciated.

[Hattie Dizmond]

@Katie Neason 

I'm sure there are plenty of Aggie Engineers running around down there!