An occasional pinhole is a problem when blow molding. The cost of manually inspecting and/or filling and draining each container would be cost prohibitive.

I would just exchange it for another one that you have visually inspected for pinholes.

If you add bleach to the tap water and store it away from direct light, 6 months should be good. You are going to get some plastic taste from just about any plastic container except for a few plastics which are too rigid for making large containers. What I do is post filter any stored water I wish to use for drinking through a Britta filter. These filters contain carbon which will absorb a lot of the plastic taste and most of the residual chlorine taste too. Don't try to filter it all through the Britta, just the water you want to drink or cook with.

Always make sure you use fresh bleach as it has a shelf life of only a few months. And don't use bleach with any additives like perfumes, etc.