We have often discussed the importance of apparatus markings when it comes to large scale operations. While you probably can quickly identify your neighboring town's apparatus, what about the pumper from across the County or the tanker from 15 miles away? When four tankers are lined up at the dump site or fill site and you can only see the back of them...then it is best that those rigs are marked so that you can readily identify them. Marking allows for better radio communications and of course markings make life as the Water Supply Officer much easier.
The folks in Stratham, New Hampshire clearly "get it" and did a nice job of marking their tanker.