Water calculation tool : Need statistics or audits based on urban water consumption patterns

I am trying to build a simple water use calcuation tool that could help a person calculate the water saved by installing water saving taps, cisterns, rainwater harvesting, grey water recycling etc. In this context, are there any statistics or audits on urban  water consumption patterns based on income levels and types of buildings in India?

For example:
1. flow rates of taps and their average running time per person per day in kitchens, bathrooms, gardens, commercial establishments, offices etc. 
2. Flow rates of showers and usage patterns
3. Types of WC cisterns and their usage patterns.

Thank you