Know what is in the ground, not what should be
Automatic tank gauging plus daily wetstock reconciliation — so a short delivery, a failing meter or a leak shows up the day it happens, not at the end of the quarter.
What is automatic tank gauging?
Automatic tank gauging (ATG) is the continuous electronic measurement of what is inside a fuel storage tank. A probe installed through the tank top reports the fuel level, the water level sitting beneath the fuel, and the product temperature. Software converts level into volume using the tank strapping chart and, where required, corrects to a reference temperature. Because readings are continuous rather than a single daily dip, deliveries, drawdown and anomalies become visible as they happen.
The reconciliation that tells you the truth
Gauging a tank is useful. Reconciling it is what actually protects you. For every product, expected closing stock = opening stock + deliveries − dispensed volume. Compare that against the real gauge reading and the difference is your variance, normally expressed as a percentage of throughput.
A small variance is normal — temperature effects and measurement tolerance guarantee it. What matters is the shape of the variance over time. Noise that averages to zero is measurement. A variance that is persistent, growing, or consistently one-directional is a problem with a physical cause, and the four usual suspects are a leak, a short delivery, a miscalibrated dispenser meter, or theft.
Run monthly, this calculation tells you something went wrong sometime in the last thirty days. Run daily against automated dispenser data, it tells you which day, which product, and often which shift.
Deliveries: checked while the tanker is still there
The system records the gauge reading immediately before and immediately after every delivery, and the difference is what you actually received. Set against the supplier docket, a short delivery surfaces while the driver is still on the forecourt and the conversation can still be had — rather than six weeks later when it is your word against a signed ticket.
Water: the problem nobody looks for until it is expensive
Water gets into underground tanks through failing seals, damaged fill points, condensation and contaminated deliveries, and it settles below the fuel because it is denser. Past the immediate risk of pumping water into a customer’s engine — and the liability that follows — standing water corrodes the tank from inside and supports microbial growth in diesel. The gauge reports water separately from fuel, so a rising water level becomes a maintenance ticket instead of a claim.
What the numbers are trying to tell you
Variance is a symptom. The pattern points to the cause — which is why daily data beats monthly totals.
| Pattern | Likely cause | What to do |
|---|---|---|
| Small variance, alternating positive and negative, averaging near zero | Normal measurement and temperature noise | Nothing. Keep monitoring the running average. |
| Steady negative variance on one product, every day | Leak in tank or lines, or a dispenser meter over-reading | Check meter calibration first, then commission a tightness test. |
| Negative variance appearing only on specific shifts | Loss associated with staffing rather than equipment | Review dispenser transactions and authorisations for those shifts. |
| Large one-off negative on a delivery day | Short delivery | Compare pre/post gauge readings against the docket; raise with the supplier. |
| Positive variance that persists | Dispenser meter under-reading, or wrong strapping chart | Recalibrate the meter; verify the tank chart against the tank spec. |
| Level dropping when no sales are recorded | Unauthorised dispensing, or genuine loss from the tank | Review quiet-period gauge data and pump authorisation logs. |
| Rising water level | Seal, fill point or delivery contamination | Water removal and seal inspection before contaminated fuel is sold. |
Guidance only. Suspected loss of containment must be investigated by a qualified contractor and a formal tank tightness test — the software indicates a problem, it does not certify a tank.
Never run dry
Reorder alerts based on real drawdown rate, not a guess — so you order before the diesel queue leaves for a competitor.
Verify every drop
Pre- and post-delivery gauge readings against the supplier docket, logged automatically with a timestamp.
Catch water early
Separate water-level reporting with configurable thresholds, before contaminated fuel reaches a customer.
Historical trends
Compare tank behaviour week over week and season over season to separate real loss from normal variation.
Tank monitoring FAQ
What is wetstock reconciliation?
A check that fuel stock movements balance. For each product, expected closing stock equals opening stock plus deliveries minus dispensed volume; that expectation is compared with the actual gauge reading, and the difference is the variance. Persistent, growing or one-directional variance indicates a leak, short delivery, miscalibrated meter or theft.
Can it detect a leak?
It provides leak indication, not certified leak detection. Sustained negative variance that delivery and meter error cannot explain is a strong signal, and quiet-period analysis strengthens it. Any indication should trigger a formal tightness test by a qualified contractor.
Do we need new probes, or can existing ones be used?
Where a station already has ATG probes in good condition, we integrate with them. Where tanks are dip-only, probes are installed as part of the project. The survey tells you which tanks need what, with costs, before you commit.
How accurate is volume from a level reading?
Accuracy depends on probe quality, correct tank strapping data and temperature compensation. The probe measures level precisely; converting to volume requires the right chart for the actual tank. We verify the strapping chart against the tank specification during commissioning, because a wrong chart produces a permanent phantom variance that no amount of investigation will explain.
Can we monitor tanks at several stations from one screen?
Yes. Tank status across every site appears in one chain view, with per-site drill-down and consolidated reorder planning. See multi-station management.
Does manual dipping stop?
We recommend keeping periodic manual dips as a cross-check on the probe, particularly in the first months. Automation replaces dipping as the primary source of truth, but an occasional independent measurement is how you confirm the automation itself is honest.
Put a number on your variance
Send us last month’s deliveries, pump totals and dips and we will run the reconciliation with you — before you buy anything.