How many quarts of water needed to raise humidity in house?

Dry bulb (regular) air temperature is in the scale at the bottom. Relative humidity is in the curves. Trace up from 20 C until you get to 30%, then go from that point straight to the right to the edge where it gives you humidity ratio.

At 30% RH, air has an absolute humidity of 4.5 grams of water per kg of air.

At 40% RH, air has an absolute humidity of 6 grams of water per kg of air.

Air occupies