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EnviroHorn™ Drain Filter

Prevent sediment and contaminants from your site entering the drainage system

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  • Avoid fines and the cost and downtime of unblocking drains
  • Oil & Sediment version retains up to 1L of hydrocarbon sheen
  • Retains up to 21kg of sediment
  • Water discharged to EA-accepted levels
  • Simply empty and reuse
  • Can be emptied in situ
  • Instructions printed on the top
  • Install in 5 minutes

Ideal for house building sites, wheel wash areas, entrances and exits to construction sites, motorway projects.

EnviroHorn is listed on the Considerate Constructors Best Practice Hub.

Prevent sediment & contaminants from your site entering the surface water drainage system

The EnviroHorn™ Drain Filter sits inside a roadside drain (gully) and filters out sediment, debris and hydrocarbons from site run-off. Water is discharged to regulator-approved standards.

You may also know these products by other names, such as a drain guard, gully filter, drain cover, drain protector or witch’s hat.

EnviroHorn™ is widely used on and near:

  • Construction sites
  • Housebuilding sites
  • Wheel wash areas
  • Highway maintenance projects
  • Car parks
  • Transport hubs like airports, ports and lorry depots

There are two types of EnviroHorn™ Drain Filter: Sediment Only (yellow trim) and Oil & Sediment (orange trim).

EnviroHorn is listed on the Considerate Constructors Best Practice Hub.

How the EnviroHorn™ Drain Filter works

EnviroHorn™ can be installed in five minutes. The conical filter is placed inside the gully pot and the large square top, which has full instructions printed on it, is cut to size leaving a 6” collar on all sides of the gully aperture. This collar is taped down onto the road using a roll of wide insulation tape. This ensures that all run-off goes through the drain filter. If the EnviroHorn™ fills with silt, simply empty out the collected sediment and refit the EnviroHorn to the drain. Alternatively, the EnviroHorn can be emptied while in situ by simply scooping the sediment out.

The Sediment-only EnviroHorn will retain 21kg of sediment before it needs to be emptied; the Oil and Sediment EnviroHorn will hold 19kg as well as up to 1L of hydrocarbon sheen. Note that if you regularly have oil sheen on your site run-off, a drain protector is not sufficient protection. You should investigate the causes and deal with them at source using other Green Rhino products.

EnviroHorn Installation Tips

Why do you need a drain filter?

When it rains, mud is washed from your site into the nearest surface water drains. This water may be contaminated with oil and fuel from equipment and vehicles. Additionally, you may pump water from excavations straight into the drains on your site.

Surface water drains run straight into natural waterways like rivers or the sea, so any silt or hydrocarbons in the water directly impact water quality and biodiversity. Muddy water can also block drains leading to flooding. Under pollution prevention legislation, you are required to prevent the contamination of surface water drains. Get caught and you face clean-up costs, project downtime, fines and even prosecution. Using an industrial drain filter like the Green Rhino EnviroHorn is the best way to comply with the law.

EnviroHorn™ – Features & benefits

  • Keeps surface water drains clean and clear
  • Removes the risk of fines, clean-up costs and prosecution
  • Water discharged to EA-accepted levels
  • Rugged and reusable
  • Install in 5 minutes
  • Instructions printed on the top
How is the EnviroHorn™ Drain Filter different to other drain filters?

The EnviroHorn™ drain filter has an outer collar which is cut to size and stuck down onto the road surface. This ensures that all run-off passes through the sediment filter before discharging into the drainage system. Other less effective sediment drain filter products tend to either sit inside the gully aperture, or be clamped down by the gully grid, potentially causing the run-off to enter the drain without passing through the filter first. Products such as these may also slip to the bottom of the gully pot where they can become ineffective and less easy to remove.

Drain covers and drain mats block access to the drain which means you are simply moving the dirty water down the road to cause a problem elsewhere. This will also leave a deposit of silt on the highway which is a skid risk and unsightly to local residents. The way that the EnviroHorn™ Drain Filter is designed ensures that there is no such issue, as all run off is properly and effectively filtered prior to discharge.

The EnviroHorn™ is extremely robust and many last the length of the project without needing to be emptied or replaced. The longevity of each sediment drain filter will depend on the volume of run-off and the volume of sediment it is carrying.

If an EnviroHorn™ drain filter does fill up with sediment then it can be easily emptied and reused, you simply need to:

  • Lift the EnviroHorn™ out using the heavy-duty straps
  • Empty the contents onto a spoil heap
  • Put the EnviroHorn™ back into the gully
  • Re-tape the edges to the surface of the road

The EnviroHorn™can be reused until the filter has become blinded and the flow rate has become too slow. In order to prolong the life of an EnviroHorn, wash the drain sediment filter out with a hose in between uses.


GRR 10 00 01 EHRNEnviroHorn Oil & Sediment Filter25cm dia, 40cm depth130L/minUp to 1L oil, 19kg sediment
GRR 10 01 01 EHRNEnviroHorn Sediment Filter25cm dia, 40cm depth140L/min21kg sediment