not all plastic food storage containers are created equal. about a year and a half ago, i moved, and decided it was time to buy new tupperware for bringing my lunch to work. i tend to bring all kinds of messy things to the office: dressed salads, things with sauces...these not only tend to leak all over your bag, they tend to leave the tupperware stained and smelly.
after some research i was directed to the tupperware website where i purchased from their "rock and serve" line. the title of the line is enough to get a person excited, i think. i shelled out a pretty penny for two different sized containers and i have never regretted it! they are air-tight, it's quite amazing. i have never had a leak. plus they still look brand new--odorless, and clean as a whistle. i cannot recommend these highly enough.
(and i guess this is another example of when to buy expensive. cheap tupperware is penny wise, pound foolish).