Home Depot for pipes and bends schedule 40, Amazon and BRS for valves and fancier schedule 80, and other specialty plumbing sites online for obscure stuff, Premiere LFS for covers and other stuff when you can’t wait, Pure Reef also sells parts further north. Other lfs probably have stuff too but you would need to check. There are really cool colored pipes people use when they treat the plumbing as a feature. We have a basement sump and fishroom, so schedule 40 white works fine for us.