This article describes where to find the model and serial number on your system, and how to interpret them.
Which system are you working with?
Depending on your model, the serial number will either be located under the top cover, or on the outside of the housing.
The serial number will be located under the hinges of the salt lid, on the rim of your water softener.
Central Water Filtration Unit (WHELJ1)
The serial number is located on the back of unit, near the plumbing connection.
Interpreting the Serial Number
Your serial number includes two pieces of information - a Model Code and Manufacturing Date. Here's an example: