He said homeowners need to ask themselves if they have more or the same number of bedrooms in your home as people.
He added: “So three bedrooms, two people – you would say yes.
“Water bills are based on the value of your house, the rateable value – so the bigger it is, the more you pay.
“Whereas meters depend on how much you use – the less people the less you use.”
Martin explained water meters are free in England and Wales.
The water meter rule “doesn’t really apply” to Scotland, and Northern Ireland has a different system.
He recommended going on to the Consumer Council for Water – CC waters – calculator to see whether you can save and how much.
If you don’t get on with your water meter, you have roughly a year to change your mind.