I use the IBC 32-oz bottles, which include screw-on caps, to store large quantities of chemicals. (I put my working print developer, stop bath, and fixer in them, for instance.) So far I've had no problems I can trace to the bottles, but I've only been doing this for a few months.
For those interested in plastic bottles, Ryuji Suzuki has a Web page on the topic:
http://silvergrain.org/Photo-Tech/plastic.html
To sum up: PET (#1) bottles are best for developers and other oxygen-sensitive materials, but HDPE (#2) bottles are bad for this purpose. Soda bottles are usually PET, whereas milk bottles are usually #2. Bottled water can come in either type of plastic. PET is less acid-resistant than HDPE, so HDPE is better for stop baths. Other plastic types can also be good choices; see the page for details.
Note that most of the collapsible (accordion-style) bottles available from photo retailers are made of HDPE plastic. There's a page somewhere on developer storage that tested these bottles and found that they resulted in reduced storage life, even when they were collapsed to minimize air in the bottles.