I have a Whirlpool side -by- side 25 cu.ft. want to know about what age it is?

It is the '25' in your model number.

Total Capacity. 25 cu. ft. Refrigerator Capacity. 15 cu. ft. Freezer Capacity 10 cu. ft.

Here is the manual in case you need it.
http://kitchen.manualsonline.com/manuals/mfg/whirlpool/ed25rfxfw01_2.html?p=1

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25 cu ft.

This is the information I could find.

Refrigerator Type Side-by-Side Total Capacity Cu. Ft. 21.7 Cu. Ft. Refrigerator Capacity Cu. Ft. 14.40 Cu. Ft. Freezer Capacity Cu. Ft. 7.30 Cu. Ft. Energy Star® Qualified Yes
for more information try this link.
Whirlpool Appliances for the Home Kitchen and Laundry Room

Bob

Read this http://www.appliance411.com/service/date-code.php

21.6 cu ft (14.5 cu ft refrig + 7.1 cu ft freezer)

Without knowing your particular model number, I checked and most 25 cu.ft. side by sides have the water filter in the grille. You just push a release button and it pops out. There is a cap on the filter, do not through it away as you will need it on a new filter. Also ensure the O-ring protective covers are removed on the new filter prior to installing. You can run the water dispenser without a filter as well. Here is a link to the PDF for one type of 25 cu. ft. Whirlpool side by side.
http://www.whirlpool.com/assets/pdfs/product/ZUSECARE/GS5VHAXWA_Use%20and%20Care_EN.pdf

check supply. or the valve

actually a bit bigger than 25 cubic feet

Total Volume 25.5 cu. ft. / 722 liter Fresh Food Volume 15.5 cu. ft. / 439 liter Freezer Volume 10 cu. ft. / 283 liter

use a hair blow dryer to warm up the chute and dry up any moisture then lube the chute with a cooking spray, pam is a good one.

What is the model number on the fridge?