Make sure you specify in contracts and specifications that contractors are responsible for obtaining all relevant building and plumbing approvals for their work.
Put that in writing but also verbally remind them in your startup meeting. Specify that they cannot start work on the site until they receive these approvals.
Get them to send you copies of their approvals.
You don’t want to end up in the situation where a contractor assumed the approvals already exist and then having to delay the completion of the project while waiting for the approvals when they apply late.