wondering how long bottled water that has been refilled in five gallon BPA free bottles will last after filling it up at a pay water station.  It is kept in the kitchen and out of the sunlight, but at room temperature

depmnds what you are asking. If you mean how long would it be safe to drink - i would say maximum of one week and would depend on whether the water source was for drinking and whether tightly sealed.

Only one week? Ouch. What happens after that time, then?

any number of possibilities depending on how clean the water was, whether sealed bottle and ambient temperature - bacteria and algae would be main concerns. Given those variables would be impossible to know whether would make anyone unwell if drunk.

Huh. I routinely drink month-old bottles of tapwater that have been sitting in the car. I guess I should get in the habit of refreshing it.

ah but tapwater is potable - we don't know that to be the case for the water from a petrol station.