We spent so much time in the water when we were cruising that we were always salty. No problems. Got so used to it that it felt funny
when we took a freshwater shower.
Saltwater is corrosive and hot salt water even more so, so could be a problem when run through the water heater. Might want to check on that.
I'm hopelessly embedded in the English/American measurement system but isn't 500 liters more than 125 gallons of water?? We've never cruised with more than 80 gallons of water and never used more than 40 gallons between fill ups. Disable your pressure water system and use foot pumps for your water needs. Your consumption
will drop through the floor.