Or open a low point drain (might as well find them now) and see if it runs clear or pink. For first usage you will need a water pressure regulator such as this to prevent excessive line pressure from damaging your internal water system (which could cause leaks in visible or non-visible locations that are quire hard and costly to repair):
Camco 40055 Brass Water Pressure Regulator by Camco
Very, very cheap insurance.
Secondly, you will need to sanitize the water system before using it even if not drinking from it. Instructions are here:
Help Sanitizing fresh water system
Then you need to drain all the chlorinated water out of the tank and the lines, refill and flush it out thoroughly until you can't smell or taste it in the water. You can use the city water connection to clear the lines (rather than the pump) but you will need to fill and clear the fresh water tank and also clear the pump and its lines by using the pump at least for that. Also be sure to clear the external shower and any other special water lines you may have within the unit. Make sure your hot water heater is online (not bypassed as it is for winterization, and drain plug in place) when sanitizing, but you should have the heat switch(es) off.