Having launched a global quest to “reinvent the toilet” last year, Bill Gates — Microsoft founder-turned-philanthropist — could soon turn his focus on the filthy toilets used by Indian Railways passengers.

In a meeting with Rural Development Minister Jairam Ramesh here on Wednesday, Mr. Gates discussed the idea of jointly funding a worldwide competition to find innovative solutions for the sanitation problems faced by 11 million passengers every day as they travel on the world's most extensive rail network.