Global internet speeds could be about to take a severe hit. An astronomic rise in P2P bittorrent traffic is anticipated next week when file-swappers share DivX-encoded files of new US shows such as Heroes and Prison Break.

A massive 4.2 petabytes of data could be downloaded next week as a result. That's the equivalent of a billion MP3s or 890,400 DVD-quality movies.

Why now? Because the new autumn or 'fall' TV season is just about to kick off in the US. TV show-swapping is rampant across the internet and bittorrent traffic looks certain to sky rocket as thousands of people start downloading the brand new shows.

Tech-savvy UK TV fans don't want to wait to see the latest episodes of their favourite US TV series. But the burden of this extra web traffic could leave ISPs struggling to cope with the load.

Will ISPs feel the burn?

The numbers don't make pretty reading. People downloading TV shows using bittorrent networks could add 4.2 petabytes a week to global internet traffic. In other words: imagine over 4.2 million gigabytes of TV show data being piped across the internet every seven days.

Astonishingly, that works out to be 6.9GB of data downloaded every single second. These are fairly modest estimates too, so the true numbers could well be a lot higher.

One show recorded in standard definition amounts to roughly 350MB, and each episode is downloaded on average around 200,000 times on average. Some are uploaded in 720p high-definition and so have much bigger file sizes, while others are not downloaded as many times as others. So it's reasonable to assume that these factors even each other out.

Roughly 60 torrented US shows per week amounts to 21GB of information. This is then downloaded, on average, 200,000 times, which uses over 4.2 million gigabytes of bandwidth.

Midweek traffic to skyrocket

Much of this traffic will go through UK servers, more people in the UK use bittorrent than any other country. And the figures don't even include those who download TV shows via other P2P networks such as eDonkey - if they did they would most likely be higher.

The autumn TV season in the US sees the re-launch of smash-hit shows such as Prison Break, Desperate Housewives, Heroes, House and Grey's Anatomy. And new shows such as Bionic Woman and The Sarah Connor Chronicles, (based on the Terminator movies) look set to only add to the congestion.

What's more, come the new year Emmy-winning shows Lost and 24 are set to start their new seasons, both airing on a Monday night. Mondays and Tuesdays will therefore see the broadcasting of the new episodes of these two shows plus Heroes, Desperate Housewives, Prison Break, Family Guy, Dexter, Curb Your Enthusiasm and more. This could lead to the majority of extra bittorrent traffic coming midweek.

We spoke to Kate Craig-Wood at internet company Memset, who said: "Bittorrent uses a huge proportion of internet bandwidth. I can't find a current figure but a few years ago it was 40 per cent of total traffic and climbing.

90% of all net traffic?

"Bit torrent maxes out a typical ADSL home connection both upstream and down, which is an unusual usage pattern and difficult for ISPs to cope with since they generally only make provisions for average usage," she continued.

"As for Heroes and Lost etc, yes, I think it will have a huge impact on bandwidth usage and net speeds. Because of the way bittorrent works it won't be all US to UK bandwidth though, it will be mostly UK to UK transfers as they are closer."

A recent article on Ars Technica suggests that bittorrent traffic already makes up around 90 per cent of all web traffic. Add to that the vast number of videos streamed on sites like YouTube and it's clear that web video is responsible for a massive majority of bandwidth use in all territories.

The rise of bittorrent as a method of transferring large files between users has led to action being taken by many ISPs. Many of them limit the amount of bandwidth that bittorrent clients can consume. Virgin Media, for example, restricts the download speed of users that download over 350MB in peak hours.

We spoke to Orange Broadband who told us: "We ask customers using file sharing software or downloading large files to do so considerately. If we see regular high usage that could impact on another user's experience, we will get in touch with the customer and discuss ways to reduce their level of usage."