The final flush on train toilets that empty their contents directly on to Britain’s tracks will be pulled in 2019, rail bosses and ministers have promised.

A combination of new trains and retrofitting old stock with modern, holding-tank toilets will end the dumping of raw sewage on the railways.

Rail firms ordered to improve provision of accessible toilets Read more

Mark Carne, the chief executive of Network Rail, said he was proud to have secured a pledge that will clean up the tracks and protect rail workers.

Carne said he had learned from direct – and rather messy – personal experience what happens to the contents of passenger toilets flushed from trains. He said: “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.”

The introduction of modern fleets has meant almost 1,000 fewer train carriages flush out waste now than in 2015, but around 500 carriages still have toilets that empty directly on to the tracks, with lines in the West Country and in East Anglia particularly affected.

Speaking at Swindon station, where the contents of a recently flushed train toilet were clearly visible on the tracks, Carne said: “It’s disgusting. 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.”

All rail franchise holders will be required by the Department for Transport to operate trains with retention tanks, to be emptied in rail depots, as part of their contracts by the end of the decade.

The move will be welcomed by most passengers and rail workers, although it may adversely affect some of the flora and fauna. Tomato plants were growing on the tracks at Swindon, and have been spotted flourishing across the network, particularly in Essex on lines from Liverpool Street. According to industry sources, the plants are believed to be the fruit of passengers ingesting cheese and tomato sandwiches before using the onboard facilities.

Unions have long campaigned for cleaner tracks. A spokesperson for the RMT union 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 halfhearted pledges – we want cast-iron guarantees.”

A spokesman for the Rail Delivery Group, which represents train operators, said: “Rail companies take this issue very seriously and understand that it can be very unpleasant for workers on the tracks. We are investing to improve trains including the thousands of brand new carriages coming into service by 2021, which have modern toilets that don’t deposit waste on tracks.”

While all timetabled passenger services will have modern toilets by the end of the decade, charter and heritage services – or “steam specials” – remain exempt.