How long can you keep fresh water?

[Loneoak]

We normally winter in Florida, but not this year because the border is closed.

The park we stay at is wonderful, we love the people there. This year they are having problems with the water system (they are on a well). A water main broke on Sunday (it's now Wednesday) and they are still working on fixing it. In the meantime, there is no water.

There have been some temporary issues in the past, but never this long. We always fill our fresh water 1/3 when we arrive and change the water every month. I suggested to DH that next season, we fill it full. He doesn't want to go through the process of dumping and refilling that much water.

He sanitizes the tank twice a year.

My question: how long can you keep water in the fresh water tank before it is no longer safe? We do not drink it, but we do use it for cooking, washing and brushing teeth. Would it b safe to fill it full on arrival and only dump it when we leave?