You are working at the wrong end of the economies of scale, and you will run into serious permit, zoning, and financial issues. A better tack to take is to figure out ways to reduce your water use.
Get/build a composting toilet. This eliminates roughly 1/2 your domestic water use. For the males, have a urinal that connects directly to waste line. Composting toilets can have issues with too much pee.
Create a grey water system. Showers and sinks go to a tank. Taht water can be used to wash clothes. That water is dumped to a tank. That water can be used in the garden, and for flushing the urinal, water for washing floors and the car.
Collect your rain water. Run this through a simple demand type UV sterilizer for one sink in the house. This is where you get your drinking water. Another branch of this circuit is your bath water. It is not as critical about being sterile? (Would you swim in a rain filled pond?)
Do not run the kitchen sink or the dishwasher to the greywater system. It has too much crud. You may need to choose bath soap with care. (bath oil residue may cling to clothes)
Even this system is non-trivial. You have to have ways to deal with both surpluses and shortages at any point in the system.
Xeriscape. Replace all ornamentals in your yard with plants that do not require supplemental water in your climate. (In parts of Arizona this means you grow rocks and cactus)
Install navy style shower controls: Punch the button once. You get 30 seconds of water to get wet. Soap up. Punch again, you have 30 seconds of water to rinse. If you have teens in your house they will hate you.
Make cleaning your plate with a piece of bread a family tradition. A clean plate may not need washing but may be sanitized directly with a UV lamp.
Use UV lamps with appropriate eye protection instead of hand washing unless there is actual dirt on hands.
Take fewer baths. Bathe at work. Tell the kids to do a good job in the PE showers because there is no hot water at home on school days. (Your spouse may have a differing point of view about this.)
Never wash the car, but do park it on the driveway on rainy days.
If it rains hard, call the kids and hand each one a towel and a bar of soap and send them into the back yard.
Install a solar heated hot tub. This can win you back some of the points you lost with the navy shower. Clean off before hot tubbing. The hot tub is equipped with a cover replaced after use to reduce evaporation.
If you have room look into using a biofilter. The first stage is a bacteria culture growing on gravel in a tank. This eats most of the solids. The second stage is whatever the brazilian equivalent of a catail bog. This will use up nitrates, phosphates. You will get evaporation loss from this pool, but, you may be able to make that up with rainfall.
