What can cause air in home plumbing?

[armylifer]

I have water that is naturally high in magnesium. My water is also very soft with a PH of 6.8, without treatment. I have measured levels of 6.6 on at least a couple occasions through the years. The only reason I have measured the PH of our water is to make sure the balance is correct for our hot tub. I measure the ph after a complete drain and refill of the hot tub twice per year.

 

[McMXi]

According to these experts ...

Causes of Air in Cold Water Lines

Air in cold water only or both in the hot and cold water is a completely different problem [compared to air in hot water lines only] and it’s likely coming from your well. We suggest calling a plumber to make sure the problem is corrected properly. Air in water lines can cause a lot more problems in your plumbing system than just splashing water all over the place when you use it.

Other signs that you have air in your water pipes are uneven water flow, air bubbles in the water, noises that can result from a phenomenon called water hammer, and problems with your dishwasher and washing machine.

Air in Hot Water Line

Air in hot water line is caused by a reaction in your water heater. Corro-Protec stops that reaction and prevent it so you don't have do deal with air in your hot water line.

www.corroprotec.com

Since you only have air in the cold water lines it seems to rule out water heater issues.