Our well went bad and we have to use a chemical toilet, because we can’t afford a new well yet. We basically have no plumbing. My son is in headstart (space just became available) and they have to do a home-visit, first. I’m really scared of this. I’m scared if people find out what we're living like, foster care will take him away from me. Am I being paranoid? I really want what’s best for him, which is why I want him in headstart, but I can’t afford anything better housing-wise.

I’m in Michigan if that makes a difference.
No, no running water. We bring it in from a friends house in jugs.

Simply say that your house is being renovated at the moment by the plumber at that exact day that the visit occurred. He should be back in a few hours as there are a few missing pieces. Leave some dirty rag as a sign. Don't leave tools as I am sure you don't have the right plumbers tools and that is suspicious.