Like James said, it depends where you are.
In Australia, Australiam Standard 1345:1995 (available on-line from
would generally permit the choice of (a) paint red all over, (b) paint red bands located as for markers or (c) pipe markers (white letters on red background for fire services. However, if there are several fire service lines side by side, red all over or red bands would not be sufficient, markers would be required as well.
Markers shall be adjacent to all junctions, valves, service appliances, bulkheads, wall penetrations etc and at spacings not greater than every 8 metres along the line (except for long, clearly visible lines where spacing up to 50 metres is permitted)
On new lines, it's easy enough to paint them red all over, and this is commonly done, but it's a waste of money to repaint an existing line.