Ask most operators how fuel goes missing and they’ll say leaks or theft. Both are real. But after reconciling thousands of tanks every month, we can tell you they’re only two of five causes, and each one leaves a different fingerprint in your data.

1. Leaks. The one everyone fears, and the one the regulations exist for. A genuine leak shows up as a steady, one-directional loss that continues day after day, trading or not. It doesn’t reverse, and it doesn’t care whose shift it is. Slow leaks are the dangerous ones: a loss small enough to hide inside daily measurement noise can put thousands of litres into the ground over a year.

2. Theft. Theft is lumpy where leaks are smooth. Losses cluster around particular shifts, particular deliveries or particular days, then vanish when routines change. Driver skimming shows up as consistent shortfalls against delivery dockets. Forecourt drive-offs show at the pump, not the tank. The pattern tells you where to look.

3. Calibration drift. Dispensers over-pouring by even half a per cent create an apparent loss that is really fuel given away free. It scales with volume: the more you sell, the more you “lose”. If your loss tracks your sales curve, calibrate your meters before you dig up a tank.

4. Temperature. Fuel shrinks and swells. A delivery dropped warm into a cool underground tank can “lose” litres by morning without a drop going anywhere. That’s physics, not a problem, but it muddles daily numbers and gets misread as a shortfall, especially on large deliveries.

5. Short deliveries. Not every docket matches what actually lands in the tank. Sometimes it’s an honest mistake, sometimes it isn’t. Without a dip before and after every delivery, you’re taking the paperwork’s word for it.

Here’s the point: on a single day’s numbers, all five look identical, a tank with less fuel than expected. Over a month of properly reconciled data, they separate. Leaks trend. Theft clusters. Calibration tracks volume. Temperature follows the weather. Short deliveries line up with the tanker schedule.

That’s what statistical reconciliation is actually for. Not paperwork for the regulator, although it satisfies that too, but telling these five stories apart before you spend money fixing the wrong one.

Overall: don’t ask “am I losing fuel?” Ask “which kind of loss is this?” The answer decides whether you call the calibration tech, the police or the excavator.