You would need to obtain the ANSI specs for each to see if there was any functional difference. I know that electrical conduit has UV inhibitors in it (that is why it is grey) while most PVC pipe is white without UV inhibitors. The other thing that I would worry about is the strenght of the PVC versus temperature. If they used a different resin for water pipe than for electrical conduit it could be a mess.
dpc is correct about the listing although I would make a correction that it doesn't need to be UL listed, only listed by a qualified independent testing laboratory. I like UL but they have been getting difficult to work with so a lot of companies are using ETL and other labs.
Yes, that would be true, subject to acceptance by AHJ. But I don't think I've never seen an ETL labeled conduit. Most engineering specs require UL labeling.
Even if you found the Sched 80 water pipe identical to the conduit, it wouldn't make any difference - you still couldn't use it unless it was marked for electrical conduit use - unless you want to make an issue of with local inspector - and I wouldn't hold my breath on that.
If the electrical distribution is used for distribution of utility power ( in an 15 KV system for example ) it may not matter. Installations on the upside of the meter are goverened by UTility standards and the NESC. The AHJ that usually inspects ( in compliance with the NEC) and OKs construction doesn't have anything to say about it.
mel 127 where are you buiding this subdivision or what ever it is? I don't want to buy a house there.
Besides the appropriate listing, other concerns are temperature rating and fittings. Conduit must have temperature rating equivalent to the conductor rating. Fittings must be constructed per conduit standards rather than plumbing stadards (e.g. bend radius).
