Yep I know, you might think: how would this affect my plant?
While it is not commonly known, this is one of the most important factors we have to pay attention to when planting our water lilies. The general rule of thumb is that water lilies need plenty of sunlight and warm water. Hence, placing you water lilies too low and we prevent young plants from receiving enough sunlight to grow well.
Tropical Water lilies prefer to be planted no less than 10cm and no more than 40cm (between 4 and 16 inches) below the surface. Placing your water lilies too close to the surface isn’t as bad as placing it too low, as it is more for aesthetic purposes. However, if you place it extremely high and the water will evaporate and dry the soil, so remember to refill your water if you wish to do this.
With new plantings, I recommend that the pot is placed just below the surface of the water and gradually lower it as the water lily grows. You can do this by starting with less water and subsequently adding more water to increase depth or use bricks (or any form of elevation actually) to elevate the plant initially and slowly remove them as it grows. Once the plant is established the pot can remain at your desired depth.
Do note that for Hardy Water Lilies, the concern will be different for people living in temperate climates. Tropical Water Lilies will almost always perish in winter and will need replanting. Hardy Water Lilies on the other hand will be able to survive the frost, thus it is important to place them deep enough, such that the crown is below the freezing point of the pond.