Question about water pH levels.

I have a question about water pH levels. I just got a pH meter I ordered in the mail and was testing my water with it to surprising results.

My house tap water is testing out at ~550ppm at around 8.4pH and the RO filtered water I got filled at a grocery store is testing with only <100ppm BUT at a 9.1pH!!!

I've made sure that dipped in the calibration solution, the pH tester is showing the correct 7.01pH value. So, can't really blame it right?

Has anyone dealt with pH levels that high? I'm not sure what to do here, would appreciate any tips.

my tap water is 8.4 and mineral water i buy in like 5 gallon things sits at 7.0.. cost too much for the mineral water so last flush i just used tap water and dropped the ph... so far no problems.. i dont know about ppm though.

My tap is 9.0, and 550 PPM so I just use some PH down to get it to 5.6 ( I Grow Hydro) and use it to good results.

yea juust get some ph down/.....im lucky my tap waters ppm is 25

cool, thanks for the responses. I'll get some pH down and hopefully it'll bring it down enough to be usable.

PH down (80% phosphoric acid) is very strong, so add only a few drops at a time and increase slowly to achieve the correct PH.
It's also good at cleaning limescale off stuff

Thanks again. This is for an aero grow, so pH is important as there will be no soil buffer. I'm going to go out this morning and look for some in-town.

I'm guess a pet store or a garden center would have some pH down? Does anyone know if any pH stabilizer would work (like something you'd find for aquariums) or does it have to be pretty specific stuff for plants?