Gravel pit

A gravel pit is an underground storage area filled with gravel. Water can be stored in the hollow spaces, which can then slowly infiltrate into the soil. Geotextile fabric is installed around the pit to keep it clean of debris. This prevents the pit from silting up.

With a gravel pit, you are not bound by fixed sizes or shapes. You can decide for yourself how big you want the pit to be. You determine the size based on how much space you have.

Costs

The main material you need is gravel. This material is relatively expensive. The costs are not too bad if you can buy remnants somewhere.

Use of space

A gravel pit has a hollow space of approximately 30%. The pit should therefore be about three times larger than the amount of water to be stored. The advantage is that you can build a terrace and lawn on top of the pit, for example. This makes the space occupied by the gravel pit multifunctional.

Difficulty

Easy to install yourself. Remember to provide ventilation and a sand trap. A sand trap is a device that ensures that sand in a flowing watercourse settles in a controlled manner. The water is thus gradually drained away.

Earthmoving

The gravel pit should be about 25 cm below ground level. You can choose the thickness of the layer yourself. The contents of the pit determine how much earth needs to be moved.

Maintenance

Only clean the sand trap and leaf trap.

Climate goals

Storing water and ensuring natural replenishment of groundwater. Natural products are mainly used.

Biodiversity

Contribution to improving biodiversity

Points of attention

  • This measure is less suitable for topsoil with a high clay or loam content, as the water does not sink quickly into the soil.
  • Please allow for a minimum of 25 cm of coverage.
  • Dig the pit to a depth of approximately half a metre the average groundwater level.
  • Choose gravel grains of approximately the same size.
  • Do not use root cloth, but rather geotextile fabric.
  • Place the vent and overflow pipe in a lower part of the garden. During heavy rainfall, rainwater that no longer fits in the gravel pit can be collected here.
  • Use a leaf and sand trap to prevent clogging. In extreme cases, a leaf trap can also serve as an overflow.
  • Take into account a hollow space between the gravel of approximately 30%.
  • Stay approximately 2 to 3 metre away metre the foundation and trees.
  • Check the vent. The downspout sometimes also functions as a vent for the sewer. If necessary, install an alternative vent.
  • Tip: replace the gravel with lava rock. Lava rock has a void ratio of 50%. This means you will need a smaller pit.

Points of attention

  • This measure is less suitable for topsoil with a high clay or loam content, as the water does not sink quickly into the soil.
  • Please allow for a minimum of 25 cm of coverage.
  • Dig the pit to a depth of approximately half a metre the average groundwater level.
  • Choose gravel grains of approximately the same size.
  • Do not use root cloth, but rather geotextile fabric.
  • Place the vent and overflow pipe in a lower part of the garden. During heavy rainfall, rainwater that no longer fits in the gravel pit can be collected here.
  • Use a leaf and sand trap to prevent clogging. In extreme cases, a leaf trap can also serve as an overflow.
  • Take into account a hollow space between the gravel of approximately 30%.
  • Stay approximately 2 to 3 metre away metre the foundation and trees.
  • Check the vent. The downspout sometimes also functions as a vent for the sewer. If necessary, install an alternative vent.
  • Tip: replace the gravel with lava rock. Lava rock has a void ratio of 50%. This means you will need a smaller pit.