ScotRail is looking for a solution to stop discharging toilet debris from its trains onto rail tracks.
The practice, much condemned across the rail network, will now be to store effluent in tanks on the train and discharge them in a specially designated area.
In the past, customers – while told not to flush while a train was in the station – would flush after using the loo, and the waste would be sprayed onto the line, something many customers, on the train and in the countryside, found distasteful.
A tender notice on Public Contracts Scotland, Abellio ScotRail said it was looking for a proposal for a solution to design, certify and install controlled emission toilet retention tanks on a maximum of 24 high speed train mark three coach toilets.
All rail franchise holders are 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.
While all time-tabled passenger services will have to have modern toilets by the end of the decade, charter and heritage services – such as the steam train specials – remain exempt.
A ScotRail spokesman said: “We’re exploring the option of fitting toilet retention tanks to our classic InterCity high-speed trains due to the late delivery of the trains from our supplier, Wabtec.”