Specify different date formats for multiple sources in ETL
I am combining a number of data sources with date columns using an ETL before performing other calculations on them.
Some of the sources have Australian date format (DD/MM/YYYY), and others have US format (MM/DD/YYYY).
The ETL gives me results in YYYY-MM-DD format, where it's actually incorrectly converted some of the dates to YYYY-DD-MM by assuming the wrong input date format. This means I end up with results from the future (eg 2018-12-03).
What's the best way to ensure the ETL always knows the correct input date format?