Low water pressure + storage tank
I have a house under construction that is just barely below the govt water supply cistern which is just a few hundred feet up the road. Our house is on the ridge of a hill, and the cistern at the peak. The water supply does not have a pump on the out supply and is gravity fed to customers. But since the foundation of my house is maybe 30 feet below the bottom of the cistern, I have very little water pressure.
I also need to get water to the third floor of my house. Right now a hose on the first floor doesnt even have enough pressure to spray above my head, and water on the second floor is a trickle.
I need to get and store water on the roof because after storms we are often without water, and I will have a solar heater for hot water on the roof.
So my idea is this...
Use a shallow well pump to pump water from the govt water supply to the roof (currently about 20 ft up, in future will be about 30 ft when we add another floor). Use a float switch and store it in a plastic cistern which can feed the cold water lines and the solar hot water system.
But now I need water pressure going back down, and Im not sure that water on the roof just a few feet above the floor below will provide enough pressure? But I also need unpressurized cisterns because after hurricanes (Im in Caribbean) we could be days without water.
Inline pumps seem very expensive. I'm wondering if I could couple the system with a bladder or pressurized tank?