Most of today’s vinegars are pasteurized and actually have very little acetic acid. They can last almost indefinitely on your shelf. If you find that the vinegar has sediment floating around or building on the bottom, just place your strainer over a bowl with a pouring spout, line it with a coffee filter or some cheese cloth and pour the vinegar into the strainer. The residue will be caught in the filter or cheese cloth. Then thoroughly rinse out the bottle, dry as much as possible, and pour the newly strained vinegar back into the bottle and you’re good to go.
You can also just as easily strain the amount needed as you go. The sediment will not hurt or affect the taste of the vinegar in question.