They don't allow any liquids, actually.
They are fine with refillable items if they are empty. We always bring an empty water bottle.
I have a friend who routinely brings stuff in baggies tucked into his body in various spots. The new policies -- no pat down, but using hand held metal detectors -- has made that method easy.http://www.seahawks.com/gameday/stadium ... items.html
The following items are not permitted at CenturyLink Field:
Bottles, Cans, Airplane Bottles, Zip-Loc Bags, Shooters
Can & Bottles
Any Glass, Aluminum and Metal Containers
Sodas, Specialty Coffees, Sports Drinks
(Exceptions are made for factory sealed water bottles and soft-sided juice boxes)
The following items are allowed at CenturyLink Field:
Empty Personal Plastic Sports Bottles
Factory Sealed Full Water Bottles (non-enhanced, flavored or carbonated)
Children's Juice Boxes & Soft-Sided Single-Serving Containers
Examples: Hi-C, Capri Sun's, and Milk products