Some good answers here but ...

Some good answers here but how to know which one is correct. In my understanding 'UFM' meant any water which was not accounted for in a physical sense rather than anything to do with finance. 'NRW' means any water which has been produced but not paid for . It would thus include the small loss of revenue which has been billed but the income not collected. There was a diagram produced by one of the water organizations showing how the various components added up to make UFW and NRW but I can't find it now. The unfortunate thing is that many of the donor agencies (eg DfID) have treated them as the same thing and set unreasonable targets based on a misconception.