To establish in detail what has occurred, typically after the failure
of a process and/or system.
To lift the drain cover up and explore what has been flushed down and try and rescue it.
We had a real problem with this customer when we delivered their goods, and they are really annoyed. The best thing to do is have a "drains up" on what went wrong with the delivery and then tell the customer what we are going to do to fix it.