It’s a common sight in public spaces: a young tree with two stakes next to it, usually secured with a tree tie, and a plastic rim around the base of the trunk. Ever wondered what this rim is for? We’ve got the answer for you!
The Water Reservoir
The rim around the base of tree trunks, also known as a ‘water reservoir,’ ensures that young trees can absorb water directly at their root ball. In built-up environments, dry soil often leads to growth problems for young trees. To ensure they take root and develop new roots before they dry out, water reservoirs are used. Water reservoirs provide a concentrated water supply directly to the root zone. In other words, they prevent young trees from experiencing drought stress and ensure they have enough water to grow.

Water Reservoirs on Onderwijsboulevard in ‘s-Hertogenbosch (The Netherlands)
Installing a Water Reservoir
A water reservoir works optimally when its diameter is as large as the root ball of the young tree. Water reservoirs are supplied in rolls, allowing the installer to easily cut the correct length. The water reservoir is then dug around the root ball. More explanation about which length of water reservoir fits which root ball size can be found in this blog article.
It’s important that a water reservoir is installed correctly to prevent water from escaping. Therefore, a water reservoir should always extend 20 centimetres above the ground and be buried 10 centimetres into the soil. The shape of the water reservoir is also a crucial factor. Follow the contours of the root ball with the water reservoir. If the water reservoir is placed oval-shaped around the tree, the water will not be evenly distributed over the root ball. Always place a water reservoir in a circle around the tree. The water reservoir is usually screwed onto the overlap inside the tree stakes.

A Water Reservoir Filled with Water
Material of a Water Reservoir
Most water reservoirs are made of recycled plastic. Both HDPE and LDPE water reservoirs are available. HDPE, or ‘High-Density Polyethylene,’ is a hard and less flexible plastic. LDPE, or ‘Low-Density Polyethylene,’ is softer and more flexible. Water reservoirs can be recycled almost endlessly. When the water reservoir is recycled, it is mixed with a small amount of plastic granulate (compressed plastic pellets) that has been recycled less frequently. This way, it remains possible to recycle the water reservoir each time anew.

Shredded Plastic Waste to Be Recycled into Water Reservoirs

Production of Water Reservoirs
Removing a Water Reservoir
For a newly planted tree, it is essential to prevent the root ball from drying out. Watering usually starts when the sap flow begins in early spring (March/April). Watering with a water reservoir can be stopped once the tree begins to lose its leaves in autumn. The water requirement naturally depends on the weather conditions during the growing season. After 2 to 3 growing seasons, water reservoirs have fulfilled their most crucial task: they have given the young tree a good start to grow into a mature, functional tree. The root system of the young tree has developed enough to manage its own water needs. Once this point is reached, the water reservoir can be removed.
Water Reservoir Collection Service
When the water reservoir has fulfilled its task, it can be handed in with plastic waste or reused for new planting. If handed in with plastic waste, unfortunately, used water reservoirs often end up in the general waste container and are incinerated. This is a massive waste because used water reservoirs are still excellent for processing as a raw material for a new product. To combat this waste, GreenMax offers customers in The Netherlands the sustainable and unique opportunity to have used water reservoirs collected free of charge by our own transporters. The used water reservoirs are recycled into a new product. This way, we have visibility over the recycling process from start to finish and complete the circle. Besides the fact that the customer does not have to pay disposal costs and is fully relieved when the used water reservoirs are collected by us, they also end up in the right place where they are genuinely recycled. Together, we can combat waste.

Collected Water Reservoirs Ready to Be Recycled Again