This ETL provides technical requirements for using alternative water sources to supply non-potable water where it is appropriate for use in Air Force facilities and on Air Force property. This ETL does not apply to the use of alternative water sources for use as potable water. This ETL does not apply to the use of non-potable water used for fire protection or non-potable surface water used for cooling, industrial processes, or irrigation, with the exception of metering and monitoring requirements applicable to non-potable surface water. This ETL does not apply to privatized water systems unless cited in the privatization contract documents. This ETL supersedes ETL 02-17, Use of Non-Potable Water to Replace Potable Water.