We've always had a water meter, as they are common here in Germany. However, in addition to the question of saving money, it's drilled into kids about the importance of saving water for the sake of the environment. Some of the things we do:
Don't use running water for washing hands or brushing teeth. Put up a sign or sticker reminding the kids to turn the tap off.
Always shower instead of bath, but then take a short shower at least once a day. Extremists switch off the shower while shampooing their hair and only switch it back on to rinse out the suds, but that's too much for me - I keep the shower running throughout - it's still less water than if I had taken a bath. We trained the DC to use a shower at a relatively young age - when they were 5 or 6.
Use the economy setting on the dishwasher - ours only takes 30 mins instead of 90 and gets the plates just as clean. Make sure the dishwasher is always stacked full before switching on (yes I'm talking to you DH!).
Get a water butt for rainwater in the garden and use that for watering plants (you can attach it to a pump to create a hosepipe effect). In fact, in 1976 there was a huge drought and a hosepipe ban all summer, and my mum used the dirty dishwater on our plants - they survived fine.
Be a lot more conscientious about deciding what goes in the washing basket, and train DC to do so too (admittedly this hasn't really gone to plan, and DD2 throws stuff in her basket willy-nilly after it's been worn for a few hours). Do you really need to change all your clothes every day, or can some things go two days? How often do you change your sheets and duvet covers? We hang ours out of the window to air frequently and thus only wash them every two weeks. If you really plan this well you can reduce your washing by a load a week.Our machine also has an economy setting, which is worth using if the clothes aren't actually filthy. And we NEVER wash stuff higher than 60 degrees.
All the best with it - meter watching can be compulsive stuff.