According to Belu's website (www.belu.org) viewed in September 2017, it use ‘ethical glass’ which is 18% lighter and 45% recycled content. Bottles made in UK. Green glass range has 80% recycled content. Plastic bottles are currently 50% recycled content.
Plus, sales of their water go to charity.
When viewed by Ethical Consumer in August 2017, Belu's website stated:
"We have partnered with the charity WaterAid since 2011 giving 100% of our profits to help to end water poverty. To date we’ve given over £2.2M, transforming 146,671 lives with safe water and sanitation. 100% of Belu’s revenues are from trading, we do not receive and grants or subsidies."

Reference:

www.belu.org (29 June 2006)