[gerdesj]

We tore our house apart somewhat about eight years ago and had all the pipe work replaced, amongst other things. We also (I did this bit because builder/plumbers generally take the path of least resistance) removed the last two lots of re-plumbing. The house was built in the '20s which is pretty modern hereabouts.

Brass is unlikely, copper is the material. The oldest pipe work I found was steel in our place - it was hard and weighed a fair bit. Copper is maleable, easy to bend and braze joints on to. It does corrode eventually but I think the thin layer of copper oxide that forms then seals in the pure copper, protecting it. The longevity of copper can be seen in the green roofs of some churches which must have looked absolutely stunning before oxidizing.