Yes. I always buy it new to make sure it is safe. Be careful with used pvc unless you know where it came from. When I was breeding some larger crays I would have a crap load of cut up pvc in the tanks. It works perfect. Each cray will pick out a section. Good luck with whatever your working with.
For my smaller crayfish I use the half inch pvc couplings. You can get them in bags of 10 or 12 for about $2 if I remember correctly. They have about a half inch inside diameter and are about 2 inches long. Since I really don't care a lot for saws and my hubby never cuts the right lengths for me, I think they're perfect.
I also use various diameter pvc for my different sized crayfish and feel they are probably the best and least expensive hides to use. You can place them so you can look through to see what's happening in them until your crayfish decide to move them to where they want them!
I am in the process of setting up some new aquariums for captive breeding studies and will be using bits of PVC pipe as caves. Thanks for the tip about using new PVC because I was going to use some older stuff that was laying around but since it is so cheap I will get new material.
If you buy pipe in diameters of 1 1/4 or smaller. They sell it in 10 foot sections. They also have a tool that I bought that can cut through it with ease. It is a pvc pipe cutter and should cost between 10 and 15 dollars. This can be bought at lowes or home depot. Saves alot of time in labor and having to use a saw to cut it. It cuts clean and leaves no rough edges to sand.
Good Luck
Yea, the pipe cutter is slick. Sort of like a racheting pruner. Works great.
I'm not using PVC though because I don't like how it looks. I get terra cotta pot dishes at are about 4" across and snip off one side to make a nice and attractive cave.
You're right, pvc doesn't look the best. I even covered a bunch of them with tank sealant and pressed gravel into it to make them look better, but it doesn't hold real well and they end up looking worse.
I get them for about 20 cents each at a local craft store. If you soak them for 24 hours it makes cracking out the opening a lot easier. You could also use a tile saw to cut them in half.