Maybe it's Plumbing Tycoon. Judging by the amount of money we have to pay plumbers, it's a good way to get rich.

Joke I heard: A doctor has a small flood and calls the plumber, who takes a look and says "That'll be £600 deposit, please." "How can you charge that much for a small job?" asks the doctor, "I don't earn anything like that as a doctor." "Neither did I when I was a doctor." says the plumber.