You might try contacting a local licensed plumber or look at purchasing an inline pressure gauge to install at your spigot that would give you a good idea of your water pressure. The 990GPH/10' means that the Liberty model SJ10 will pump water up 10 feet at a rate of 990 gallons per hour or 16.5 gallons per minute (GPM). Liberty is one of the top manufacturers of pumps in the U.S. and their product is very well built and designed. While there may be better, more expensive systems out there, we currently offer only two water powered backup systems. This and the Bur-Cam model 300402.
Depending on the water table in your area and the potential for flooding, you could go with a water powered or battery backup sump pump system. If your water removal needs are below average, you could elect to go with a low GPH rated battery backup sump pump or water powered backup. Please note that water powered systems will only work if you have a municipal water supply with a minimum of 20-100 PSI. They will not work if you draw your water from a well. A low output system would provide between 300-1000GPH. If you're in a little higher water table that the flooding potential is a bit higher, you may want to consider a battery backup system rated at between 1000-2300GPH. If the flooding potential and water table are very high, you might look at the systems rated at 2400GPM and higher.