A tool which calculates the amount of carbon emissions being produced by a council website's homepage has found Watford Borough Council to be the worst in the UK.

Data published on the Open Innovations site showed Watford's emissions to be nearly twice as high as anywhere else and ten times the average with more than 400 local authorities analysed.

Council websites, just like any website, can impact the planet because data centres, transmission networks, and the devices we use to access them all use electricity which, in turn, produces carbon emissions.

Each visitor may only produce a few grams of CO2 emissions but when taken over time - and over the number of visitors - that can soon add up.

For instance, if your page generates 1g of CO2 per visit and you get 10,000 visitors a month that works out at as much CO2 as boiling water for 5,700 cups of tea a year.

On January 4, a table published on the Open Innovations site showed Watford Council's homepage generated around 13 grams of carbon dioxide per visit - second placed Redcar & Cleveland generated 7.47. The average was 1.28g.

A website carbon calculator, created by Wholegrain Digital, was used to assess the council websites.

Watford Borough Council says it took "immediate action" when it was informed about its high carbon emissions - but new data published on January 11 showed the council still 'topped' the rankings, albeit at a lower 10.26g.

The council says its high carbon emissions are because of high resolution images on its homepage that have since been reduced.

A spokesperson said: "Our redesigned website went live in November and since then, our customers have told us that they find the site both more engaging and easier to use.

"Although the site is new, we actively manage the site on an ongoing basis and use all feedback that received to continuously improve the site however we can – especially where it is having a negative impact on our environment.

"Having been brought to our attention that the site's carbon emissions were high we took immediate action to reduce these levels as much as possible in the immediate term, and have introduced further governance to maintain these lower levels and will be working with our website supplier to further reduce our sites emissions as much as possible in the future."