I understand the difficulties people have. We've all had to overcome obstacles. The obstacle we have to overcome here is how to get you growing as best you can with what you have.
First, tomorrow, perhaps you could call your local state health department, and ask if they do water analysis. Tell them your building claims the water is "not potable, and I'm afraid to drink it". Hopefully, the state does free analysis of this sort.
If they do free analysis, don't do anything grow related or make any purchases until that analysis comes back. Post that here and we'll help you further.
If the state doesn't provide free testing and you can't get water testing done within the budget you can afford, I honestly don't know what more to say, other than do the best you can with what you can afford and find, and hope for the best.
However, if the building owners are telling you outright that the water is contaminated beyond the point of it being potable (ie. drinkable), you have far serious worries to think about beyond what soil you need.