NETWORK Rail’s boss has experienced the horror of the train flush menace first-hand.

Mark Carne, chief executive of the Swindon-based organisation, told the Guardian: “You quickly learn to turn your back and close your mouth when you’re trackside and a train is passing. As I know first-hand.”

His comments came as rail firms prepare for a ban on trains flushing their toilets directly onto the tracks.

By the end of the decade, all rail franchise holders must operate trains with retention tanks. Rather than emptying their pans onto the tracks, as often happens now, trains will have to hold onto this waste water until it can be emptied at rail depots.

Network Rail’s Mark Carne spoke to the Guardian at Swindon station. “It’s disgusting,” he said of the evidence of a recently flushed toilet trip visible on the tracks. “I’ve been out there with the track workers and you see it coming, like a plume of steam.

“It’s totally unacceptable and I’m pleased we’ve got government agreement.”

A Network Rail spokesperson added that the improvements were possible following track improvement work:

“As part of our Railway Upgrade Plan we have improved infrastructure across the route which allows new trains to run which do not dispose of waste onto the track like some of the older fleet,” he said.

“Further planned route modernisation means fewer and fewer trains which dispose of waste onto the track will run on the railway.”

The RMT union has campaigned for an end to the practice of flushing toilets directly onto the tracks – which it says leaves its members “sprayed with human sewage”.

A spokesman said: “We want to see a firm schedule that forces the train operating companies to stop this foul and disgusting practice, which leaves our members out on the railways regularly sprayed with human sewage.

“We’re not interested in half-hearted pledges. We want cast-iron guarantees.”

Great Western Railway said that their new high-speed trains boast toilets with retention tanks. The new trains will start replacing the old Intercity fleet on the London to Bristol line from the end of this year.