'My water company has raised my bills by 50% but is refusing to fit a meter - what do I do?'

Reader Rachael got in touch with the Money team after her water bill went up by almost 50%...

I've just been told my water bill is rising by almost 50%. We are retired, our kids have flown the nest and we live in a four-bed detached house.

Our bills are through the roof even though we hardly use any water - we don't have a hosepipe for our garden and we take short showers. But our supplier is refusing to give us a water meter.

What can we do? Money blog editor Jimmy Rice tackles this one... Thank you for your question, Rachael.

The general rule of thumb is that if you have more bedrooms than people in the house, or even the same amount, you could save money by having a water meter - so you're right to want one. Since 1990, it has been mandatory for new homes to have a meter.

Yours is an issue we hear about a lot with water companies refusing to fit one on homes older than that. Read all the latest Money news here Citizens Advice points out that you have a right to be charged for your water on the basis of what you use (tenants also have the right to ask for a meter if their tenancy agreement is for six months or longer) - with one big but: "You have a right to have a meter installed free of charge, unless it's not practical or is unreasonably expensive to do this." It might not be practical if the water supply is shared, if there is inaccessible pipework or the water company cannot find a suitable location for the meter.

"If you can't have a water meter installed for any reason, your water company may be able to put you on a cheaper tariff to save money," Citizens Advice says. How your water bill is calculated Most unmetered homes are charged based on the "rateable value" of their home.

In a nutshell, before April 1990, every property in England and Wales was given a rateable value based on how much the property could be let for. Which, clearly, isn't very scientific.

What can you do? As Citizens Advice advises, ask your supplier, which is likely to be Southern Water, whether they can put you on a cheaper tariff in lieu of a meter. It is sometimes suggested that households ask for an "assessed charge.