One fine day, Aunt & Uncle Drew received a ludicrous water bill. They challenged it immediately. The first functionary they spoke to said, well that can't be right: pay 'x' (a more reasonable amount he nominated) for now, and we'll look into it. So they paid 'x'.
Six months later, another bill arrived - seeking an even more astronomical amount, plus the 'arrears' from the previous bill, all in menacing red ink. Another 'phonecall: but this time the water company people sucked audibly on their pencils and said the 'arrears' had better be cleared or there'd be trouble - have you been taking lots of baths? So A & U demanded to speak to a supervisor, who passed them on to 'debt management', who took a more emollient line. Since A & U are on the 'senior' side of life, they could agree a 'payment plan' which, provided they adhered to it, would cause the amount to be re-classified from 'arrears' to something less penal. Then the matter would be looked into.
To be fair, the payment plan was set at a pretty modest monthly amount, and it defused the red-ink crisis. But after a few weeks, with no progress towards sorting the matter, further pointed 'phonecalls were made until some genius at the other end said: maybe there's a leak ! Could you turn off everything, go and peer at the down-hole meter, and tell us what you see. This task fell to yours truly (being slightly better able to crawl around on the pavement etc) and lo ! - with everything turned off the little dial was perceptibly turning. Ahah said the voice on the 'phone, that sounds like a leak !
There then followed some dialogue about whose responsibility this might be etc etc which need not detain us: suffice to say they turned up, discovered the meter itself was leaking, fixed it; and negotiations are ongoing as to what should be the deemed usage during the period of the leak.
Ah yes, the period of the leak. Can we retrospectively identify with reasonable accuracy when it started ? Oh yes we can ! - take a butchers at this graph of the average monthly usage, drawn up on the basis of several years' worth of half-yearly bills carefully archived by A & U, plus ongoing personal readings of the meter to ensure justice is served.
Yes friends, we can indeed spot the leak. A nasty one, I'd say, getting progressively worse until they fixed it. All that lost water ! And not too difficult to estimate the amounts, either.
Among several points one could make about this kind of nonsense, let's think about simple, nay, trivial data mining. A usage pattern like the one above (produced by myself using nothing more complicated than Mr Microsoft's excellent spreadsheet) could not plausibly be accounted for by extra bath-nights chez Aunt & Uncle Drew. Given that the water companies are supposed to be on notice to improve their statistics on wastage etc, not to mention customer service, what could be simpler than an automated check for egregious outliers like this ? Even if they can't stretch to pre-emptive data mining, couldn't the response to distressed 'phonecalls be based on simple after-the-fact analysis of no greater sophistication than the one wot I did ? At the click of a mouse ?
Mr Tesco has been doing vastly more advanced - and proactive - stuff than this for yonks. Ditto the banks, ditto the telecomms companies. Why are utilities such rubbish ?