Infrastructure Leakage Index (ILI)

Infrastructure Leakage Index (ILI) is a performance indicator for water loss used in monitoring DMA zone performance. It measures the ratio of current daily real losses (CDRL) to unavoidable daily real losses (UDRL).

ILI uses all of the metrics from a mass balance analysis, including usage, non-revenue water, and derived data such as minimum nightly flows. Additionally, ILI compares all of this with zonal pressure sensors, and takes into account physical properties of your zone like joint material, length of main lines, and number of connections, to look for pressure anomalies that would indicate leaks.

Note: In Info360 Insight, ILI measures daily losses not annual losses.

To create an ILI calculation

1. Go to Tools Infrastructure Leakage Index.
2. Click New ILI, enter a name and description, then click OK.
3. Configure the Current Daily Real Loss (CDRL) bearing in mind the following:
   1. Mass Balance: You need to have created a mass balance calculation before you can create an ILI calculation.
   2. Minimum Usage Period: Select the time window to use for the Minimum Night Flow (MNF).
   3. Night Usage: Enter the estimated usage volume for the time window specified above.
   4. Orifice Exponent: Choose the orifice material to determine the exponent used in the calculation or set a custom exponent value.
   5. Estimate from Zonal Usage: If you mark this box, Info360 Insight will use the selected Mass Balance to derive the Minimum Usage Period, Night Usage and Orifice Exponent.
      Note: Your Mass Balance must have billing sensors configured for this option to be available.
   
4. Configure the Unavoidable Daily Real Loss (UDRL).
5. Save the configuration and click Calculate.
6. You can see the results on the Calculated Result tab, and you can also choose to add a chart with the results to a workspace.

   Whenever you refresh the results, these will also be refreshed in the workspace chart.

Basis coefficients for UDRL

UDRL (litres/day) = (18 x Lm + 0.8 x Nc + 25 x Lp) x P

Where Lm is the length of the main pipes in km, Nc is number of service connections, Lp is the total length of underground pipe between the edge of the street and customer meters in kilometers, and P is average operating pressure in meters.