Some of the NIT's best for Environmental Engineering are:

• NIT Trichy
• NIT Warangal
• NIT Surathkal ( better reputation)
• NIT Nagpur ( proximity to NEERI)
• NIT Surat

To know more about each of this colleges visit the link below:

NIT Trichy:

https://www.careers360.com/university/national-institute-of-technology-tiruchirappalli

NIT Warangal:

https://www.careers360.com/university/national-institute-of-technology-warangal

NIT Surathkhal:

https://www.careers360.com/university/national-institute-of-technology-karnataka-surathkal

NIT NAGPUR:

https://www.careers360.com/university/visvesvaraya-national-institute-of-technology-nagpur

For NIT SURAT:

https://www.careers360.com/university/sardar-vallabhbhai-national-institute-of-technology-surat

To know more about  Environmental engineering visit the link below:

https://www.careers360.com/courses/environmental-engineering-course

I hope this answer helps. All the very best for your future endeavors!