Welcome to the party Dennis!
Tough question... I'm sure you will get a lot of different answers from different people... Only you will be able to determine what is enough.
Water treatment is probably a good idea as you can carry things to treat water a bit easier than carrying a large quantity of water.
What type of survival situations do you feel you and your family may be in?
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"I reject your reality and substitute my own..." - Adam Savage / Mythbusters