The only way to avoid the platic flavor is to purchase bottles made with the right plastics, or recycle soda-pop bottles.
When you can taste the plastic, you are ingesting chemicals leached from teh plastic. A high-scholl girl did a science project on foods and liquids stored in plastics to see if any harmful chemicals were transfered to the food. They were, and in alarming amounts. The result of her science project was more public awareness that only certain plastics should be used to contain food and liquids to be injeted. The safest of the plastics is PET. It did not contaminate the food with anything. Of course the safest material of all is glass, which is absolutely inert, and cheap, but beakable. For long term storage, glass is best. Following glass, stainless steel, the PET plastic.
There is a triangle found on every plastic container that tells what it is made of. There are several sites on the Web that tell what the plastic is, and its safety.
Do a bit of research on this one. It can affect your health, and the health of your family.
Seeeeya; Goodweed of the North