In short
Yes, high-quality artificial grass is water-permeable. Rainwater drains away through drainage holes or a permeably coated backing. However, the sub-base is the main factor in determining whether the surface remains dry: In the garden, a compacted gravel-grit sub-base ensures infiltration, while on concrete, tiles, or balconies, a slope and ideally a drainage mat are required.
Puddles, moss, and unpleasant odors on artificial grass almost always have the same cause: water cannot drain properly. Here we explain how the water permeability of artificial grass works and what you should look for in the product and installation.
How does water get through the artificial grass?
| Backing type | Function | Note |
|---|---|---|
| Backing with drainage holes | Water drains through regularly punched holes | Widely used for garden artificial grass |
| Fully permeable backing | Water flows away across the entire surface | Uniform drainage |
| Closed backing | Little or no water drainage | Only suitable for indoor areas or covered surfaces |
Read more about the structure of the backing under Backing and Backing Coating.
The sub-base is the deciding factor
The best artificial grass is of no use if the water cannot move further beneath it. Depending on the sub-base, the following applies:
| Sub-base | How water drains |
|---|---|
| Soil/Garden | Infiltration through gravel base layer, leveling layer, and weed membrane |
| Loamy or compacted soil | Thicker base layer, additional drainage if necessary |
| Concrete, pavement, tiles | Slope to the edge or drain, drainage mat |
| Balcony, roof terrace | Slope, drainage mat, keep drains clear |
The individual layers and their thicknesses are explained in our guide Artificial Grass Sub-base.
What happens if water does not drain away?
- Puddles and permanently damp spots
- Moss and algae – see Moss and Algae
- Odors, especially with pets
- Frost damage and lifting in winter
- Faster aging of the backing and sub-base
Checking and maintaining water permeability
- When purchasing: Check manufacturer specifications for water permeability and pay attention to the backing.
- During installation: Compact the sub-base well, plan for a slope, and do not use impermeable foils.
- During use: Remove leaves and dirt regularly so that no dense layer forms.
- For sports surfaces: Loosen compaction in the infill through deep cleaning.
Is artificial grass bad for infiltration?
Properly installed, water-permeable artificial grass allows rainwater to seep into the ground. Unlike fully sealed surfaces, the water cycle is fundamentally maintained. It is crucial to avoid using water-impermeable foils under the covering.
Our advice
All our Royal Grass® garden products are designed for outdoor use. We check your soil before installation and plan the sub-base and slope so that water drains reliably. More on artificial grass installation.
Frequently asked questions about water permeability
Is artificial grass water-permeable?
High-quality artificial grass for outdoor use is water-permeable – either via drainage holes or a fully permeable backing. To ensure the surface remains dry, the sub-base must also be able to absorb or divert the water.
Why are puddles forming on my artificial grass?
It is usually due to the sub-base: it is too heavily compacted, uneven, or lacks a slope. A dense layer of dirt from leaves and dust or a closed backing can also obstruct water drainage.
Does artificial grass need drainage?
In the garden, a permeable gravel-grit sub-base handles the drainage. On solid surfaces such as concrete, tiles, or balconies, a drainage mat in conjunction with a slope is recommended.
Can artificial grass be laid on foil?
We advise against this. A water-impermeable foil prevents infiltration and leads to waterlogging. Use a water-permeable weed membrane instead.