Unknow dagger, maybe Philippines?

[Rick]

Hi Ian,
I missed your response. That kind of pipe is often used as buried septic pipe; you would probably have to find some at a plumbing supply wholesaler or possibly a contractor's supply business. That is where I found mine. There is a Mast Maker (sailing) in our local industrial park; that's where I first spotted this tubing. They use it to ship spars to their customers.
We had to install a new leach field at the house. You can see it in place in the trench pictured below. It comes in various sizes; the tubing I used to ship was 10 inches inner diameter IIRC.