Eel Screens and Eel Regulations Compliance

Complying with the Eel Regulations – Our Self-cleaning Filters are Eel Friendly.

If you are pumping and screening raw water you may be affected by the current Eel Regulations designed to help the recovery of populations of European Eels. The relevant legislation in the UK is ‘The Eels (England and Wales) Regulations 2009 Statutory Instrument No. 3344’.

The installation of low intake velocity eel screens ahead of pumping equipment may be a condition of your water abstraction licence.

What’s happening to the Eels?

Eel regulations - an eelThe regulations have come about due to a catastrophic decline in the eel population – succinctly described here in the Environment Agency Eel Manual Overview.

The regulations set criteria for the use of raw water and screening and pumping equipment. In simple terms, the regulations seek to ensure that Eels at all stages of life are protected.

The Eel regulations are concerned, in part therefore, with the intake velocity of pumps screens and strainers, the angle of approach and the size of mesh.

Serendipitous Design

Eel friendkly filter complying with eel regulationsBy happy chance the design of Rotorflush self-cleaning suction intake filters lends itself to compliance with current Eel Regulations. Rotorflush self-cleaning suction intake filters make ideal eel screens ahead of pumping equipment when abstractiong raw water.

Our filters operate by drawing a high volume of water through a large open area at low velocity, and backwashing debris wildlife etc. away from the mesh from inside the filter.

For most flow rates our filters meet requirements for the protection of all eels, including elvers.

Does this affect me?

The Eel Regulations affect all industry sectors abstracting, diverting or discharging into raw water, and may apply to you if:

  • you abstract more than 20 m3 in any 24 hour period
  • you have equipment (pumps, screens filters etc) that may obstruct Eels
  • or if you are installing or altering equipment that may obstruct Eels


Want to know more?

Pisces Conservation are an excellent Hampshire based specialist environmental consultancy with an impressive track record working within the power industry.


They have a website dedicated to understanding the current Eel Regulations.

Pisces also offer software and training, and are an invaluable environmental resource for industry.


What are the Eel Regulations?

A guide to the regulationsPisces Eel regulations logo


Do they affect me or my business?

Who is affected, who is exemptPiscesConservation1

glasseel1The Eel Regulations require companies in the UK and the EU who abstract and use raw water to ensure that their activity enables at least 40% eel “escapement”.  This is a requirement that came into force in 2015.

Ensuring that this figure is met may require specialist input by conservationists such as Pisces Conservation.

Companies can meet this and other requirements by implementing measures that reduce the harm to eels and elvers from pumping equipment and intake and outfall screens.

The Environment Agency (EA) has noted that Rotorflush filters can make an important contribution to Eel recovery, particularly for seasonal or temporary pumping applications   Section 4.5.1 of the EA “Screening at intakes and outfalls: measures to protect eel” says:

“Few manufacturers offer self-cleaning strainers that are appropriate to temporary works. One of the few available is the Rotorflush RF Series of self-cleaning inlet screens for surface-mounted pumps.”

The design of our filters gives them a low intake velocity and a high open area, enabling compliance with current Eel regulations when pumping and abstracting raw water. The table below gives examples of how our strainers and filters meet the Eel Regulations.


Example Chart – How Rotorflush Products meet Environment Agency Guidelines for Eel and Elver Protection

Pump Size

(inlet/delivery bore size mm)


(litres/sec (cumecs))

Glass Eel /

Elver Protection

(required screening surface area for 2mm gap size and 0.15 m/sec approach velocity) in m2


Solution / Product

(2mm perforated mesh has 40% open area this is accounted for in approach velocity)

Small Yellow

Eel Protection

(Required screening surface area for 3mm gap size and 0.20 m/sec approach velocity) in m2.


Solution / Product

3mm perforated mesh has 50% open area this is accounted for in approach velocity

Large yellow Eel /

Silver Eel Protection

(required screening surface area for 10mm gap size and 0.30 m/sec approach velocity) in m2


ution / Product

6mm perforated mesh has 50% open area this is accounted for in approach velocity


15 (0.015)


RF400R 2mm mesh 0.149m/sec


RF400R 3mm mesh 0.132m/sec


RF400R 6mm mesh 0.132m/sec


34 (0.034)


RF600-300R 2mm mesh



RF600-300R 3mm mesh



RF600-300R 6mm mesh



45 (0.045)


RF600-400R 2mm mesh



RF600-400R 3mm mesh



RF600-400R 6mm mesh



90 (0.090)


RF1000-500R 2mm mesh



RF1000-500R 3mm mesh



RF1000-500R 6mm mesh



161 (0.161)


RF1500-600R 2mm mesh



RF1500-600R 3mm mesh



RF1500-600R 6mm mesh


Note: The maximum screen aperture we supply is 6mm. 2mm apertures have a 40% open area, 3mm and 6mm have 50% open area. All our pump intake screens are self cleaning with approach velocities between 0.1 and 0.15m/s.
We consider a continuous self-cleaning action is essential to preserve approach velocity values. If a filter starts to block the open area will reduce and the approach velocities will rapidly rise. Our gentle but effective continuous self-cleaning technology protects wildlife.


Contact us for more information about how our products can help you abstract or move raw water without blocking strainers, pumps and other equipment while complying with current regulations.

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