I had a water meter fitted at the last house and saved a lot of money, but I was on my own then, working full time and with the commute was only at home for 10 hours a day, when I didn't go out in the evening after work!
Now there are two of us, both retired and at home in the day time. We spend longer in the shower because we move slower, need the loo every couple of hours (I worked out 20 flushes a day on average...), use the washing machine more because we tend to leak, and so on. Plus the other half insists on washing most dishes by hand before loading the dishwasher. We also have a garden pond which needs topping up with tap water when the water butt runs dry! so I have resisted having a water meter at this house because I think we are likely to need more and more water as we get older. I am afraid of winding up like my mother who moved to a house with a meter & was so worried about the water bill she stopped showering regularly, only flushed the loo once or twice a day etc.
Most water boards (or whatever they're called now) have a calculator on their website which you can use to determine whether you are better off with a water meter; I suggest you check this before you commit as once you opt for a meter you are stuck with it!