The bio-toilets, which have been indigenously developed by Indian Railways and DRDO, have been installed for in-service trials in nine trains, he said during Question Hour.
"By 2016-17, all new coaches built in the country will have bio-toilets. By 2020-21, all coaches will have bio-toilets," Bansal said.
He said such toilets are being installed in existing coaches through retro-fitment but the process costs five times more than building new coaches with bio-toilets.
"The estimated cost of retro-fitment in existing coaches is expected to be approximately Rs 15 lakh per coach while in case of original fitting in the new coaches the cost will be about Rs 3 lakh per coach," he said.
The quantum of work and material required in case of retro-fitment is significantly more which makes it a costly affair. Rs 7,000 crore would be required for this project, Bansal said.
Gwalior-Varanasi Bundelkhand Express is the first train to have a bio-toilet.
