My supplier wants to install a water meter but I think it will cost me more: Can I refuse?

I recently received a letter from my water company, Cambridge Water, saying it would be installing a water meter at my home. 

It said it needed to do this because we live in a 'water-stressed' area. 

We're a family of five in a three-bed house and given we water the garden, run baths for the kids and dog and wash our two cars I think we must be fairly heavy water users. 

I think having a meter would cost us more. Is the meter compulsory or can I refuse?

Sophie Warburton of This is Money replies: Around three in five households in England and Wales now have a water meter. Since 1990, all new homes have had to have one installed.

The devices record how much water your household uses, with your supplier using those readings to calculate your bill. 

If you don't have one, your water usage is estimated by your supplier. 

What are unmetered water bills based on?  

The system is based on historic property values, rather than how much water a household uses.

Customers without a meter are charged based on their home's 'rateable value' - a measure of how much a property is worth based on its location and size, set by the Government's Valuation Office Agency. 

The system assumes that more valuable homes are larger and have more people in them, meaning they use more water. 

That means some large families can benefit from unmetered charging, while some people living alone in larger homes may pay more than they would on a meter.

What is a 'water-stressed' area? 

Sophie Warburton replies: A water-stressed area is one where demand for water is close to, or exceeds, the available supply. 

Parts of the East of England where you live are among the driest regions in the UK, with a growing population placing increasing pressure on water resources. 

Water companies serving water-stressed areas can apply to the Government for permission to introduce compulsory metering as a way of reducing water consumption.

Your supplier, Cambridge Water has done this in order to install water meters in homes across Cambridgeshire and Bedfordshire.

It is not alone in this. Many water companies across Britain are moving customers on to a meter or strongly encouraging them to have one installed. 

The company says the move is needed to help protect water supplies in the face of climate change, population growth and increasing demand from new housing developments. 

Can you refuse the water meter? 

I put this question to Andy White, social policy and charges expert at the Consumer Council for Water. He said: Some water companies have been given permission by the government to introduce compulsory metering programmes as part of a wider package of measures to reduce the pressure on water resources. 

Where this permission has been granted to a water company, a customer cannot refuse to have a water meter installed. 

Cambridge Water is among the water companies that has been allowed to introduce compulsory metering.

In other areas of England and Wales where metering is not yet compulsory, customers can usually trial a water meter for up to two years with the option to switch back if they are unhappy.

Would having a meter cost more? 

Andy White replies: As a general rule of thumb you're likely to save money with a water meter if you've got fewer people living in your home than bedrooms. 

So in the circumstances you describe and with your family's level of water use, it's likely you will end up paying more with a water meter. 

CCW has a water meter calculator on its website which can help you work out more accurately what you're likely to pay.

How can I keep water bills down?  

Andy White replies: There are many ways to keep metered bills lower. For instance choosing to have showers instead of a bath, or opting to use a bucket to wash the car rather than a hosepipe. 

Water companies also offer lots of water-saving freebies to use in your home.

If you're struggling to afford your bill, water companies have social tariff schemes to help households on a low income. 

There is also the WaterSure scheme, which can cap the bills of metered households in receipt of benefits who have three or more children or a medical condition requiring extra water use.

Cambridge Water has been approached for comment.