A pH of 7.0 is neutral. pH can vary quite a bit out of the tap... and if you measure directly out of the tap, dissolved CO2 in the tap water can artificially lower the pH. To wit, my tap water tests at 7.0-7.4ish, but if you sit it out a day or agitate it (so that the CO2 outgasses) it is consistently 8.2-8.4. There are few people whose water out of the tap tests 8.8 to 9.0, so 8.2 is not outrageous at all.
Most fish, if acclimated right, will be more than happy in a pH of 8.2. It is far, far, far more crucial to keep a steady pH than a pH in a certain range. Unless you have an exceptionally delicate fish (I am thinking of discus as an example -- this is where research pays off) it is a changing pH that can kill the fish more than keeping fish in a pH that may not be ideal, but is steady. This is the far greater danger of using pH down chemicals and the like -- it takes a lot of the chemical to adjust hard water, you have to do it with every water change, and you have to test very frequently. If you really want to lower your pH, filtering the water through peat or buying/generating R/O water is the way to go.
But, let me tell you a success story. As I said above, my pH is steady at 8.4. I keep tiger barbs, lemon tetras, scissortail rasboras, aeneus and trilineous cory cats -- all of which have spawned at various time -- and all of which 8.4 is above their "ideal pH range" from any profile I've seen on the web or in books. But, the pH is steady, I do frequent water changes, I let the water sit out a day before using it for the water change so that the pH is exactly the same as the tank water, etc.
If the fish have been in that water for months and happy, they have acclimated. I would look to some other cause for the deaths. It is possible that your city's water is being treated differently or maybe even from a different source. Have you added any new fish? decorations? changed food or water conditioners? Have you medicated for anything recently? Might you have done filter maintenence and possibly destroyed your bilogical filter? Have you accidently spilled, even a tiny amount, of a cleaner or any other foreign substance in the tank? Has anyone else, like a child or a tanksitter? And finally, are the ammonia and nitrite readings consistently 0, and the nitrates low (<60 ish)?