First you start out when your young on a Farm with only Tank water, usually OK but sometimes tastes like a dead Frog or has a few Mosquito rigelers but you get used to a few rigelers that you sift out between your teeth as that is ALL the water you have! (Get over it Sunshine so to speak)
You don't become a delicate little butterfly buying water in plastic bottles at 1,000 times the price of Tap water.

I carry around 80 ltrs of water on long trips (No Trailer) - 60 ltrs in a water Bladder behind the seat & two 10lt Plastic water containers for on board Tap water & for two people in the vehicle that is plenty.
We do tend to pick up water from places we know are OK.
Only once in twenty odd years of outback travel have we ever had a problem & that was when Olga cleaned her teeth with water at Innaminka.
@cookie64 is spot on in his post.