pH of water way off

[BOMBAYCAT]

I would really rather be all organic but the pH of my tap water is way off. The water sits in jars for a week before use and has pH of 8.1 and out of the tap it is 6.9 pH. The Milwaukee pH meter is calibrated. Water comes from the mountains and is pretty clean. When I mix nutes the pH goes down some but not enough. I nute locked a sensitive Sativa a while back so I am cautious about having the right pH. What causes the tap water to be off so much?

 

[Adze]

Bombaycat,
Lots of organic matter from forests tends to make soil acid and desert soils tend to be alkaline, that affects the water. Where I am from the water has a PH of 7.2 from the tap, I let it sit overnight with a hand full of peat moss tossed in, and this lowers the PH and lets chlorine evaporate out too. I've had problems too, hope this is helpful.