I am homebrewing for my second time and will be bottling tomorrow. I have a large bottle from a local brewery and it is a Grolsch type bottle. Can these be re-used? Do I need a new rubber washer? How many times can the washer be used…or how do I tell when I need a new washer?
Thanks… 
The washers are good for lots and lots of uses. You’ll be able to tell when it needs replacing once it kinda dries out and starts to show cracks.
I bought 2 cases of 1-liter flip-tops and have used them several times with the same washers and they have been fine so far. I did also get an extra bag full of them just incase but for now i just clean and spin them.
Even if it’s the big growler size flip top, it’s definitely reusable. You may have a harder time finding replacement gaskets, but the gaskets last for many uses.
Also if it is a big growler size bottle remember that you might want to use slightly less priming sugar. Not sure of the amount but that is probably info that can be found online somewhere.