Technically, I don't think you're allowed to bring in outside food. We do bring in snacks with us and they kind of just overlook them. However, we've never attempted to bring in drinks since we have the refillable cups, which we usually just get filled with free ice water and add a flavoring packet.
As stated the rules do not allow you to bring in anything, there are even signs at the entrance stating that. However, we bring in all types of stuff packed in a small cooler....sandwiches, bottles of water, cans of coke, lunchables, cookies, etc. We go 2 or 3 times a month and never have a problem.
Thanks guys. We will take our usual collection and keep our fingers crossed. Luckily the value of the items is only a few dollars but could save us 10-15!