Very true but But the water in my tank is the same water I use everyday.I don't filter my city water at home. The water in the tank is the same water.
It's only the same water WHEN you put it in. It is not the same water when the temps rise and bacteria starts to grow in the 'holding' tank.
So many people think that if they put water from their 'house' into their RV, that all is going to be okey dokey because it came from their faucet. Yes when it comes out of your faucet it is safe and hopefully bacteria free AND the cold comes out at a constant temperature.
The water that comes out of your faucet at home is NOT sitting in a holding tank. So taking good house water and putting it in a holding tank does not mean it is going to 'continue' to be bacteria free. An RV holding tank takes on the ambient temperature of what ever the temps are outside. 80 degree weather? You fresh water will be 80 degrees, perfect for bacteria growth and bloom.
City water: is highly treated before you get it and it is provided fresh 'running' thru water pipe lines.
Well Water: Is coming from the ground thru natural filtration and is pumped from 'running' water.
RV water tank: Put any of the above water into a plastic 'holding' tank that is not sealed and you NO longer have bacteria free water.
The bug you get from what you think might have been too much beer or granny's coleslaw from a picnic could very well be from the bacteria in the water in the holding tank. Will it kill you hopefully not but when I am RV'ing I don't want to take time out to be in the bathroom all day from bad water! :B