Homemade ph calibration fluid?

may be a dumb question, but I have to ask.

is there some known store bought (walmart) products like drinking water that has a known PH value thats regulated by the manufacturer. distilled water? Anything that has consistent ph value?

I have PH calibration fluid but I used it about 8 times by now. And would guess that the fluid is not at 7.0 seeing I keep my PH meter in tap water.

by moving it to the test fluid, it would raise the ph, Right?

Or does it have buffers in it to keep it at 7.01?

Thanks

P.s I have made my own 7.0 fluid with PH down. I rinse my meter in it. In hopes this will keep the test fluid from changing its PH.

Calibration solution is good for months, even years, provided it is used correctly. Don't dilute it, don't contaminate it; before moving your probe between calibration solutions, wash it and VERY gently dry it with a tissue- just wick the water away, don't actually touch the glass.

You'll also burn out your probe quickly if you store it in tap water. Store in pH 4.00 buffer if you have nothing else.