Here you see you do need a blue jar or two but just place them in front of your clear jar and the blue rays shine through. You can see the blue rays on the ground.
Placing your jars on the ground is extra beneficial when weather allows. A windowsill works too. Note a house plant grows well through a Window’s light in the winter. So will your water charge in the sun. If you place your jars on the ground make sure it’s on the dirt. Not grass. It acts as a buffer and doesn’t get the best charge. One hour minimum is best.