With some plastic tubing, used coffee containers, and phone books I made a system that increases the volume of water available for a live Christmas tree and makes the adding of water to the system easier.
The trick is to adjust the heights of the new reservoirs so that, when filled, they do not exceed the elevation of the top of the stand reservoir. The tubing is used to establish siphons between all containers.
The offset reservoirs make filling easier and increase the volume of water available.
The molded handles in the coffee containers help to secure a loop of tubing near the bottom.
As long as the siphons are not broken, all water levels should be identical.
This system was created for an office. Modifications would be needed for homes with pets and children.