That’s a frequently asked question. You should water them approx. 2 times a week and keep the soil slightly moist. Place the potted lily in a bright, sunny spot. However, avoid placing them in direct sunlight.
If the sun shines strongly, the pot lily can quickly dry out. This is evident from the sheen that the green leaves develop. That is the moment to give them more water and perhaps put them in the shade. So on warm days feel free to water the plant every day.