what is the hardest thing about being a plumber and why?

I am not a plumber but have done most jobs of a plumber and have a few relatives that are plumbers. Depending on the type of plumbing, the area's of risk when dealing with plumbing are sweating copper as well as working with high pressure lines. Snaking out traps and primary egress lines can be difficult. With older septic systems, you will find that most of them will have roots inside and need replacing. This work is outside work and requires lots of digging. Not all plumbing companies will do the digging work themselves.

Waking up early could be considered a hard part of the job as well as weekend emergency type work (even though you still get paid for it). You will also have to drive a good amount and will have to work with customers often. You will also have to deal with your suppliers, be able to mark up your parts and write up invoices for work performed.

Most plumbing companies have a few roles for a plumber. One is doing installations, toilets, hot water heaters, etc... Then there will be guys who go out to sell the job. If the job is a repair, depending on the company, they will do it or have a repair tech come out.

Overall, there is nothing that is very difficult with the job per say except there are several labor related tasks that could eventually take a toll on yourself.

I am not a plumber, but having availed of plumbing services at odd hours of the day/night, the first thing that comes to my mind is: What working hours does a plumber keep? I believe it depends on whether the plumber is associated with a construction crew working on projects (think new housing, re-modeling etc) which will likely have regular working hours. On the other hand - if the plumber is part of a "call-me-if-you-need-help" setup, then it'll likely mean keeping very irregular hours (including nights and weekends). I hope you get feedback on other elements of a plumber's job.