Isn't that only new builds and renovations? You mean the instantaneous water heaters, that have an incredibly small header tank right? (sorry, I'm not a plumber so not up with the proper terms)
Pretty much any new boiler fitted nowadays is at mains pressure and has no gravity feed cold water tank at all.
Consequently there's getting to be less and less flying stuff from the loft in the water.
Even the new ones with large accumulator tanks and solar hot water don't have a gravity feed cold water tank.
