Last year, Severn Trent put in a water meter for our house without our permission. 

We only discovered this when my wife approached the installer on the path outside and asked what he was doing.

We have now been switched over to a metered bill.

This is a problem as I am a keen gardener, and water my garden a lot in the hot summers we are now experiencing. We don't want to be worrying about how much we use. 

Severn Trent says we had to have a meter because we are in a 'water stressed' area. Is it allowed to do this? Can we switch back to an unmetered bill? J.P, Gloucestershire

Helen Crane, This is Money's consumer champion replies: About three in five British households have a water meter, and they can be your best friend or your worst enemy - depending on how much you use. 

With firms continually trying to push up water bills to sort out their pollution problem and fund upgrades, a meter can be a handy tool for those who are thrifty with their water usage and keen to save money. 

But, at 81 years old, you told me you have 'never had any interest whatsoever in having a water meter installed' even though you are on a fairly tight budget. As you put it, 'My plants are more important to me.' 

You believe you save money by not having a meter - and this is because of the slightly odd way in which water firms bill customers. 

If you don't have a meter, you'll be charged based on typical usage. However, instead of calculating that on the number of people who live in your home, they base it on the home's size and how much it is worth.

This is known as its 'rateable value' and it is based on estimates made of how much someone would pay to rent the property. These were done by the Government's Valuation Office Agency in 1990, so are rather out of date. 

The system assumes that bigger and more expensive houses will have more people living in them and use more water, and therefore charges them more. 

It means that if you live in a big house, with more bedrooms than people, you might be being overcharged for your water and could be better off with a meter.

Severn Trent assumed this was the case for you in the letters you started receiving in late 2025, informing you that you would soon be switched to a metered bill. 

'On the run-up to Christmas everyone is feeling the pinch,' it wrote in December. 'So, it's good news that we've looked at your bill and worked out a way to save you money.' 

The message is a little condescending for my liking, given Severn Trent plans to increase bills by 47 per cent between 2025 and 2030. 

But more shockingly, it told you you would be switched to a metered bill automatically, after 14 days. 

What if you had missed the letter, or been away for the holidays? It seems as if the firm did not want to give customers much choice but to switch.

You wrote back immediately, telling it you didn't agree to a metered bill. It responded in January with some generic frequently asked questions about the switch. 

It said your area, Gloucestershire, had been identified as a 'water stressed area' by the Environment Agency. 

I asked Andy White, billing and affordability expert from the Consumer Council for Water, if this meant it could install a meter, even if you didn't want one. 

He explained: 'Some water companies have been given permission by government to introduce compulsory metering programs 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.'

While it might not seem like it on a rainy spring afternoon, some areas of Britain are, at times, in danger of not having enough water to supply all the homes they need to because of climate change and a rising population. 

But the letter had a heavy-handed tone, saying that 'change isn't always easy' and asking customers to get in touch if they felt 'overwhelmed' by the changes. 

It also seemed like a generic mail-out, and didn't provide any answers specific to the concerns you had raised. 

It wasn't clear whether this was indeed a compulsory switch, or whether the firm was simply trying to coerce you into getting a metered bill. 

This is key because, for people who choose to switch to a meter voluntarily, water firms must allow them to switch back within the first 12 months if it doesn't work for them. If you are switched automatically by your supplier, you can't change back. 

Exasperated and confused, you got in touch with me for help. 'I have resisted electricity and gas smart meters, but it looks as if I am not going to be able to fight this one,' you wrote. 

I felt you were being bullied into having a meter. 

I contacted Severn Trent to ask whether it was really forcing you to do so. 

Initially, it sent me a response that was as confusing as the letter you received. 

It confirmed that the meter was installed to check for leaks, not because the area was water-stressed - although that is also true. 

But it failed to say whether it would let you switch back to unmetered. 

A spokesman told me: 'A meter was installed to help identify leaks in the area. 

'The customer's account was moved to a measured bill in December but as their water usage is higher than first anticipated, we're speaking to the customer to make sure their bill is one that best suits them, while also providing useful tips on how to save water in their garden.'

I put some more probing questions to the water supplier, but before it could respond you received a further letter in the post. 

It confirmed after my intervention you would not be moved to a metered tariff, and said that following an investigation, it concluded you would not save money. 

Your garden is safe... but perhaps not forever. 

The letter concluded that, if your area continues to be 'water-stressed' then Severn Trent 'may look to enrol more customers' in the metered system in future. 

There aren't many upsides to a wash-out summer, but I think you will be hoping for one if it keeps your lawn out of Severn Trent's crosshairs. 

For customers who are interested about getting a meter, the Consumer Council for Water's Andy White says it's 'worth checking with the water company first to see if you have the option to switch back.'

CCW also has a water meter calculator on its website where you can check to see how much you're likely to pay with a meter.