Cumulative % Variance = (Cumulative Variance x 100)/Cumulative Sales

' + 'Find the Cumulative Variance and Cumulative Sales by adding the previous day’s to the daily variance of sales for that day.

Check and confirm all data is correct and accurate, and note any changes to stock levels, seasonality, delivery, "throughput, pumps/meters, and equipment. Also see variances sub section.

Could there be a leak? Investigate and take action.

Check and confirm all data is correct and accurate and note any changes to stock levels, seasonality, delivery, throughput, pumps/meters, and water level and if it is a compartmented tank. Also see variances sub section.

Could there be a leak i.e. water ingress? Investigate and take action.

Do you use a dipstick?

Check you have the correct size dipstick for the tank.

Check you are reading the scale correctly.

Vapour recovery systems can have an effect due to pressure differences, installing a Pressure Relief Valve may help.

Do you use an automatic tank gauge (ATG)?

Check the type of ATG you have:

• Hydrostatic gauges – similar accuracy to dipstick, gauge maybe unbalanced or could be having problems accounting for the effects of vapour recovery, installing a Pressure Relief Valve may help.
• Digital gauge – depending on the probe type you may have a stuck float, distorted tank, poor calibration or a contaminated probe.

Check delivery amount is accurate and has been taken into the correct tank. Possible issue with fill point. Also check variances sub-section.

You may have a leak or you may have meter issues, investigate.

Yes, There are generally increases in losses during warmer summer months and increased gains in colder months due to the fuel contracting or expanding. Although you should still check that you don’t have a leak.

Variances on low selling fuels will be accentuated as the percentage loss on the tank is calculated based on sales.

Using statistical methods to detect earlier and smaller leaks will help. You may wish to speak to a company who can offer this support for you.

Have you changed your delivery supplier? If not you may have a leak so you will need to escalate and investigate or you may have had a theft.

Inform your Local Authority, Fire Officer and Environmental section and take any action to minimise the health and safety risks.