Peter, I have a bit of experience with the topic. My signature has a link to rainwater harvestinh. Perhaps read it and come back to be with questions.
For a start I would make theses suggestions for consideration;
- Have a storage tank which can hold 6 months supply of water
- fit a rainfall collection system that will work in your area.
- do you get snow etc, remember I live in rural Australia.
- dont bother about water treatment systems, a large storage tank will address that issue.
- dont mix city water with the other stuff, keep it separate.
- do you use much town water?
- fit first flush units to the roof gutters.
Tell me about the area.
- is it dusty?
- do you have trees around the house?
- what do you wish to use water on?
- how is water drawn from the creek?
I have found out this about the area.
- is one of the driest places in western Washington.
- 17" of rain a year, much the same as where I live.
I am going to suggest the following subject to a better understanding.
- draw water from the stream to fill a big tank, separate from the other sources of water.
- Direct all roof water to another tank if possible.
- the existing small above ground tanks could be used to catch water from remote sheds and pump it back to the large one.
- i would consider not using the well.
- you will be able to drink rainwater without treatment.
- Dont mix the different sources of water, mainly in case something goes bad, you can find the cause.
Rainwater can be used in the household
Creek water gardens and toilet flushing
Town water back up only.