You can buy a new float switch retrofit assembly. Essentially, you'd tie the existing float up so that is always on, then you plug the new float switch into the wall, and then the pump into it. Then when this new switch trips, it applies power to the pump to turn it on. Adjust it to any height you want. Assuming your local water utility puts chlorine or some other chemicals into the water for distribution, you can take a sample of what's in the pit and have it analyzed to see if it contains that chemical. If it does, it is likely a pipe leak. If it doesn't, it's likely ground water. Ground water is fickle...it all depends on the soil composition and distribution. you could have it higher than your neighbors. If your water meter isn't turning, it ends up being utility's water that's coming in, then you'd have to talk to them about fixing it. If it's ground water...you'll have to live with it. If your meter is turning without you having anything on, you're paying for it and would want to find and fix the leak.