What must an umpire check before a game starts?

Before the game starts you must make sure that (law 43.2.1):

1. Bowls: all bowls have a clearly visible, valid World Bowls Stamp imprinted on them.
2. Rink width: the rink of play is the correct width, by measuring it. Rinks must be between 4.3 and 5.8 metres wide for outdoor play, and between 4.6 and 5.8 metres wide for indoor play (law 49.1). For domestic play, Member National Authorities can decide the standard for the minimum width.
3. Distance markers: the pegs, discs or other markers on the side banks are the correct distances, by measuring them. They mark 2 metres and 25 metres from the end ditches (law 49.12).

Also, before play, one trial end must be played in each direction on the rink the game will be played on, although for domestic play the Controlling Body can limit this to no trial ends or one trial end in one direction (law 5.1).