Several UK rail franchises are sticking with the horrifyingly outdated practise of discharging flushed toilets directly onto the tracks, as efforts to retrofit the national fleet with new rolling stock and/or septic tank facilities have ground to a classic halt.
Therefore you will be advised not to flush the toilet in stations on some trains operated by Abellio's East Midlands Railway franchise for the foreseeable future, as the Department for Transport has given it a new deadline of 2023 to sort out the issue that still affects some trains departing from London St Pancras on the proper grown-up mainline lines. Over the hills on services offered by the West Midlands franchise, a spokesperson said it might have the issue solved by the end of this year, mind, thanks to a mixture of updated carriages and the clever approach of... simply locking the doors of toilets that don't comply.
The lack of what they call controlled emissions toilets is still ongoing on ScotRail too, with a report in the Guardian adding that some trains operated by Northern and Transport for Wales are also guilty of pumping human waste out onto the tracks too, much to the grim horror of network maintenance staff and truant schoolchildren. [Guardian]