Yes, you can bring your own water without having it confiscated. The trick is freeze it the night before. They will let you bring frozen water but not regular water.
You can bring your own food too! I typically pick up a Jersey Mikes SUB sandwich with the oil and vinegar on the side. I cut it in quarters and pre-wrap each. I oil them up when eating to keep them fresh. The alternative is paying a premium price in the airport or taking your chance on the plane. On a Delta flight to Tampa last week, the attendant apologized for running out of food before serving the whole plane. I was glad I brought my own food.
Pre-boarding trick. I personally register online and use my cellphone as my boarding pass. One of the benefits is unlike your boarding pass, the electronic boarding pass is read cellphone face down. That means if you are in zone 4 and want to board with an earlier zone, they won't notice. Try that with a paper boarding pass and it never works.
TSA Pre-Approved. TSA Pre✓ provides expedited security screening benefits for flights departing from U.S. Airports. Global Entry provides the TSA Pre✓ benefit plus expedited US customs screening for international air travelers when entering the United States. TSA Pre✓ costs $85 and Global Entry costs $100 for a five year membership. Travelers interested in Global Entry must apply through the Trusted Traveler Program website.
For frequent global travelers, Global Entry, NEXUS, and SENTRI are programs of U.S. Customs and Border Protection. These programs offer travel benefits to pre-screened members. If you join Global Entry, NEXUS, or SENTRI, use your membership number as a “known traveler number” in airline reservations to receive TSA Pre✓®.