What is AWWA M36 water audit?
The AWWA M36 water audit is the American Water Works Association method for auditing water systems and controlling losses. It sets out a standard water balance in which system input volume is divided into authorized consumption, apparent losses and real losses, so utilities can quantify non-revenue water and target the losses that matter.
What it is
M36 is the AWWA manual Water Audits and Loss Control Programs. It replaced older percentage-based measures of unaccounted-for water with a structured balance that every utility can complete the same way.
The balance starts with system input volume, corrected for meter error. Authorized consumption is split into billed and unbilled, metered and unmetered. What remains is water loss, split into apparent losses, such as customer meter inaccuracy, data handling errors and unauthorized use, and real losses, which are physical leaks, bursts and overflows.
AWWA's Free Water Audit Software implements the method, along with data validity grading and performance indicators such as the Infrastructure Leakage Index.
Who it applies to
Water utilities across North America use M36, and several states require it, including California and Georgia. Large campuses, airports and military bases with their own distribution networks can apply the same balance internally.
How it is measured
An audit is only as good as the data behind each line, which is why validation and data grading matter.
- System input volume from production or purchase meters
- Billed metered and unmetered consumption
- Estimates of unbilled authorized use and apparent losses
- Real losses derived from the balance
- Data validity scores for each input
How Aqueduct helps
Aqueduct supplies continuously measured volumes per district for each line of the balance and shows where real losses sit. Your team completes and files the audit.
- aQ WaterGuard water balance from source meters to each district, refreshed every 60 seconds
- Minimum night flow baselines per district that point to real losses
- Meter health and data gap checks that improve data validity
- aQ Assurance exports of measured volumes for the audit period