James,
I think it important to remind the readers of survivalblog to assess their water supply situation in the event of a local or national emergency. Much of the western united states even the well irrigated areas are actually truly considered high desert and could nor supply even 10% of the population should access be lost to the water supply infrastructure. Unfortunately many people have lived their whole life with functional first world plumbing and the clear knowledge that magical faucets, toilets, and shower heads will always have a supply of clean potable water.
It is imperative that anyone planning a retreat have redundant water supply plans including water table maps and locations of springs and open bodies of water. Planning must include which water tables are affected by drought.
The best sources of water are existing deep wells or open un-dammed bodies of water, plans must include how to pump or transport the water to your retreat.
Since water is probably the most important strategic asset to a retreat there must be plans to protect and access remote water sources especially in the face of bandits who might attempt to monopolize this asset. Pre-crisis would also be a good time to secure and possibly purchase a clear legal share or long term lease to water rights on nearby properties. – David in Israel