Cistern pump selection help

I have a 15 foot deep spring encased in concrete 12 feet deep with about 7 feet of static water. I also have a 1200 gallon storage cistern about 25 feet away buried, lift is only about 5 feet. I am thinking of using a sump pump with built in float switch for simplicity and high flow rates to fill storage tank. Are there potable water rated sumps available. Also ,the wall of the spring is about 14" thick and only a 1" pipe coming out. If pump has 1.25 will that damage pump or significally reduce flow? Or, would I be better to suck the water out with a shallow well pipe at 10-12 GPM 1/3 or 1/2 hp mounted in near by well house. Also on a float system is a normally closed type used to shut off pump when storage tank is full? I seem to find conflicting info...Thanks in advance