Installing a water meter is definitely going to help you pinpoint and cut your usage by being more careful with your water consumption.
However, will it save you money? A good question and hard to answer. It depends on the size of your current household and which region you live in.
The Money Saving Expert website has some good advice on this subject and the table below provides your potential saving by having a meter installed compared to the size of your household and region. Can you save with a water meter, see the calculator here