An irrigation and water source was imperative to keeping the garden alive. The most complicated irrigation system used canals. This required that the water source be placed at the highest part of the garden so gravity could aid in the distribution of the water. This was more commonly used with raised bed gardens, as the channels could run in the pathways next to the beds. Kitchen garden ponds also were used in the 14th and 15th centuries, and were meant to offer ornamental value as well. Manure was placed in the ponds to provide fertilization and water was taken straight from the pond to water the plants.