-If you need a well that produces xx GPM for your home and/or vineyard needs, you can pay to have it tested.
-If you need to check the quality of the water, you can have it tested.
-If you need to be sure the septic is operable, you can have it tested.
These are reasonable contingencies you should check. I agree with Al Sovey that it usually takes 2-3 weeks to have all the tests completed and the results back to you.
It's complex -- a lot depends on whether or not there is a house currently, what you plan do with the property in the future, etc. But the general answer is yes you will always be checking out the well and septic. Email me privately if you want additional information.