But the service said it was working round the clock to ensure the safety and wellbeing of key workers including NHS staff who were using the 500 services still operating on the network.
It said trains were being cleaned frequently with the main focus on high contact points including tables and handles.
In the past six weeks, additional cleaners have been employed to cover day and night shifts at train depots throughout the Wales and borders network, as well as the deployment of extra cleansers on trains.
Transport for Wales Rail Services (TFW) safety and assurance director Leyton Powell said: “The safety and wellbeing of our customers - the majority of whom are key workers - is an absolute priority for us, as well as the protection of our staff who are keeping the rail network running.
“We are using an anti-viral cleaning product with a seven-day protection period, under-pinned by cleaning trains thoroughly at least every 24 hours, plus regular cleaning of major contact points such as tables, handles and anywhere where people may regularly place their hands.
“We have increased our cleaning teams to build our capacity for the additional cleaning required and provided them with the necessary equipment to stay safe themselves. As key workers they are all doing a remarkable job.”
TFW recently launched a social media campaign to encourage passengers to stay at home and is offering free travel for NHS workers.
Welsh Minister for Economy, Transport and North Wales Ken Skates added: “As we continue to fight this crisis, it’s really important that we provide essential travel for our key workers and Transport for Wales are doing that in very challenging circumstances.
"The expansion of their cleaning capabilities to ensure the safety of customers and staff is therefore welcome.
“I’d like to take this opportunity to thank all those who are working hard to ensure our transport network is clean, continues to function and supports the country during these difficult times.”