I just installed a reverse osmosis and deionizer water filtration system, and it is extremely slow. I calculate that it will take 3-4 hours to filter out 10 gallons of water.
I am planning on filling up two of my 5 gallon plastic buckets the night before brew day, and snapping a lid on it. So 5 gallons of water will be exposed to air for roughly 1.5 hours while it is filling, and be exposed to the air inside of the bucket after I snap the lid on.
I recall reading that water will naturally absorb carbon dioxide from the air, and this will increase the level of carbonates in the water, making it harder and increasing its pH.
My goal is to replicate the purity of the distilled water I buy from Walmart.
Is this something I should be concerned about, or would the distilled water contain similar levels of carbonates due the absorption of carbon dioxide from the air?