no, no, no, no. First off you should be watering with around 6.3 ph water. I would guess that something was off on your reading though because 4.7 is extremely low, from just draining through your soil. Test the soil directly and then test the run off before it hits your drainage dish and let us know what you get. Did you by chance eat a lemon over your pots, because something must have gotten in your drainage tray to throw the water off that much. Just do the retests and let us know, this way we can figure out where the source of the lower ph is. It is possible I would guess that over the course of many waterings you have washed a lot of lower ph substances out of your soil and so now you have very low ph build up at the bottom of your drainage tray.