Flying with liquids - advice & potential problems

Once upon a time, airlines would allow passengers to bring liquids on board without any special restrictions. However, those days are gone, and in spite of occasional rumblings that the current regulations will be changed or dropped, that has not happened yet. I don't think it's likely to happen very soon either.

If you've traveled by plane in the last few years, you probably know the rules by now:

• Liquids also include gels, creams, and products like chapstick.
• Each liquid in your carry-on has to be in a container no larger than 100 ml (3 ounces).
• The containers with your liquids all have to be put into a clear, 1 litre (1 quart) plastic ziploc bag. 
• Each passenger is allowed one such bag in their hand-luggage.

Those are the rules, and here are my tips on how to deal with these rules, especially if you're traveling with kids:

1. There are exceptions to the rules
There are special exceptions for things like baby food and prescription medication. Usually, you are allowed to bring those things with you on board. Just be prepared to prove that you have a prescription for any medication, and that it is actually baby food in the containers.
The problem: While bringing such items is usually allowed (check with your airline before you leave to be safe!), it will slow you down when you go through security.
My advice: If at all possible, avoid bringing liquids over and above the "regular" allowances, simply because it will speed up getting through security. Bring formula powder, and ask for warm water on the plane to make formula. Also: Bring wet-wipes for diaper changes and to clean your hands, rather than hand sanitizing gel or sprays. Wet-wipes do not count as liquids.

2. Tax-free shopping can be problematic
Buying items like perfume, beauty products and liquor can be cheaper in the tax-free shops at airports and on board the airplane. However, if the container you just bought holds more than the allowed 100 ml (3 ounces) that can cause problems during your journey, especially if you're going on more than one flight.
The problem: Airport shops will usually seal your purchase inside a plastic bag, and that will then be allowed on your flight. Products you buy on board are often treated this way too. If you buy products on one airline's flights, you should be able to bring them on other flights with that same airline as long as the bag remains sealed. However, if you're changing airlines you might have to check the product rather than bring it on board with you.
My advice: Ask before purchasing, just to save yourself a potential headache!

3. Water bottles: some can stay, some have to go
Water bottles, whether disposable or refillable, are a great thing to bring on a flight, especially if you have kids, but bringing a full water bottle through security is not allowed of course. The way around this is to buy, or fill, a bottle once you're inside security. Then you should be able to bring it on board. 
The problem: Sometimes though (especially if you're traveling on long-haul flights, such as those between North America and Europe), the airline will have their own security checkpoint at or near the gate before you're allowed to board your flight. If you have a water bottle, you will then either have to throw it away, dump the contents, or drink it all right then and there. Very annoying, but not much you can do about it!
My advice: Bring a refillable water bottle because it's a really good way to save money and be a little more ecologically conscious at the same time. Just be ready to drain it if you have to. I'm still hoping the idea of water-filling stations at airports (like at San Francisco airport) will catch on!