Measuring water consumption in an apartment - Need alternatives to expensive meters

  I want to know how we can measure consumption of water in our apartment.We have a borewell and water is pumped into an overhead tank daily.

  In our locality, we have seen that borewells of many neighbouring apartments have dried up. Our apartment is taking proactive steps to reduce water consumption and also to reuse/recycle as much as possible.

  To see the effectiveness of what we are doing, I wanted to measure the consumption at a periodic interval (say 1 month) to see our progress. Once we are successful, we can share our best practices.

  I understand that there are water meters, but they are quite expensive. Are there ways to do this easily without having to spend 4-5k?We can live with an accuracy of few tens of litres for this measurement.

Thanks

Kiran.