I never boil sausages. Lightly simmer in a favorful liquid--seasoned stock, juice, beer, wine, water, depending on the sausage--yes, but never boil. Often I just grill indirect at moderate temps then, depending on the integrity and fat level of the sausage, might move to direct to finish.
I make the decision whether to steam/simmer based on the sausage and on how I'm serving. If I want the sausage's flavor to be boosted or tweaked before grilling I will make enough of the liquid mix to come about halfway up the sides of the sausages, laid single-layer in the pan, and gently heat at a low simmer, pan partially covered, for 15-30 min, depending on the size of the sausages, turning them once. These I'll either immediately grill or will cool and grill later when I need them.
Sometimes I steam as above, then grill, then retrn to the liquid mix to hold them (kept very low) till serving time. Mostly they're just served directly off the grill.
Imo, plain water robs sausages of flavor and boiling, regardless of liquid, pushes them toward overcooked pretty easily.