My Little Pig doesn't drink much either. When you wash the veg, give it to your piggy still wet for extra water. Also worth checking out this water bottle (
http://www.amazon.co.uk/Superpet-Ch...s=pet-supplies&ie=UTF8&qid=1317242412&sr=1-18)
It is made of glass and has a much longer spout than normal bottles - so they get more water per nibble.
If you are ever concerned that they are not drinking enough, you could always try syringing water. Little Pig won't fall for just plain water being syringed, so I mix it with a Vit C tablet, a pinch of probiotic and a pinch of Recovery - he has a few syringes of this every evening.