Reading through the care instructions for house plants on this site, I came across some advice that I have never heard a knowledgable plant-person state. On the page for the Rubber Plant (http://www.plantideas.com/in/in36.html), it states "water three times a week"!

How does the writer know what time of year it is, what type of container is used, how large the plant/container is, environmental conditions, soil mixture, plant's health, etc.?!?! These conditions all determine how often a plant needs to be watered, but all of that is beside the point. The only way to determine the right frequency of watering a plant is to test the soil.

In addition to my previous points, three waterings per week is enough to support a water lilly! If you are growing your Rubber Plant in sand, then maybe that watering schedule is appropriate. 8)