Chop the rhubarb into very small pieces, enough for 3 cups. Place the rhubarb in a skillet with the maple syrup and water. Over medium low heat, bring to a simmer and cook, stirring, until softened and most of the liquid has absorbed, about 10 minutes.
Add the chia seeds. Continue to cook and stir until thickened, about 5 to 7 minutes. Turn off the heat and stir in the orange juice. Taste, and add additional orange juice if desired.
Pour into a canning jar and refrigerate: the rhubarb jam will continue to thicken as it cools. Keeps for 1 to 2 weeks in the fridge. Serve on toast, over oatmeal, or swirl into yogurt with crunchy granola or nut toppings.