What are the Causes of Rapid Sand Filter Clogging?

Hello, I am working with municipal water treatment facility in Delhi, India.

We are facing a huge problem at our water filtration plant as sand filters are clogging/choking every 4-6 hours.

This problem is making our water filtration vulnerable and we need to backwash the filters multiple times per day. This is harming our water treatment efficiency.

Can anyone suggest a reason behind it and, if possible, a solution?

Please help.