I follow the sanitation process every spring. Pour a half cup of bleach into the fresh tank with it half full of water then turn on the pump and faucets to distribute it thorough the lines. Let it sit there for an hour and flush out until the bleach smell is gone. Drain and refill the fresh tank and rinse it out too. We use city water too mostly but use bottled water for coffee and drinking really. Just our thing we do even though I would still drink the water we are hooked up to.
It is a it of a process but worth the preventive measures to keep the system clean of anything that might want to grow in it. Leave the pump on to listen for signs of any leaks. The pump will run for a second or 3 if there is a leak. Wear old clothes you won't mind ruining with white spots too.