U guys use 15/20mm alkathene for residential water mains?       Isnt that low density polyethylene? (LDPE)

I usually use and have always come across MDPE Blueline for a buildings water supply, or if its a dated older watermain HP Pvc, galv, or copper while doing maintenance work etc

I only see alkathene for garden sprinkler systems residentially or for farms rurally, stock trough water supplys etc, never seen for potable supply.