Well I've just bought Grants Minitex Jim..........so nearly there :
Apart from time saving, to arrive already armed with "on-board" water looks so much more professional than sticking a bucket under the clients tap. When they ask "what do you need?" and your answer is (with a smile on your face) "for you to go and sit down and leave me to it, oh and a nice cup of tea please" they sort of join in the fun and admire your tools