How - and how often - are you supposed to wash the Nikken water bottle?

I asked one person who said they never washed their bottle because they were always using it. I didn't get any cleaning instructions with mine. But it seems to me like it should be washed to prevent bacteria build-up, etc.

I washed my bottle part in the dishwasher and it seemed to do fine. But what about the straw and top, etc., that seem to be connected to the filter? I haven't had to replace my filter yet so I haven't tried to take it apart. I might just try that later.

Anyway, does anyone (maybe a Nikken rep) have any suggestions on cleaning it?

Thanks!