One of the biggest problems with plumbing systems is how difficult it can be to keep them in good condition. When an air conditioner or heater malfunctions, it can become pretty clear early on that you need to call for repairs. If nothing else, you can always give the system a quick look if you’re concerned that it might be malfunctioning in some way.
The plumbing system, though, is hidden throughout the house. You aren’t going to be able to really inspect it without professional equipment, which is why it’s a good idea to schedule a pipe inspection appointment at least once a year.