Are your outlet grilles a lethal danger to swimmers?

‘There should be at least two outlets per suction line at a sufficient distance apart to prevent a body being drawn or trapped by two suction line outlets. The amount of suction produced at any single outlet position should not be sufficient to result in a body being drawn towards it and held in position or entangle hair’

Extract from Managing health and safety in swimming pools HSG179.

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A single sump outlet grille is a lethal threat to swimmers of all ages

Single sump pools are extremely dangerous. If a person were to lay over the outlet they could be sucked onto it whereupon a vacuum would form. This vacuum would be extremely difficult to break and could easily result in the person drowning.

To prevent a fatality from happening swimming pools need to have at least two outlets. These should be a sufficient distance apart to ensure no single person can block it. In order to achieve this, the sumps should be around 2 meters apart.


These outlet sump grilles are less than 2 meters apart and pose a threat to swimmers

An additional danger with single sump swimming pools is entanglement. A single sump can form a vortex due to high flow rates. If hair is sucked into this vortex through the grille it will spin around and become entangled and knotted, trapping the person below the water.

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An anti-vortex grille can reduce the risk of entanglement and entrapment


Anti-vortex grilles can be fitted by Commercial & Specialised Diving to sump outlets to help ensure entrapment and entanglement does not occur.

Commercial & Specialised Diving can conduct a hazard and defect survey on your swimming pool that incorporates checking the conformity of the swimming pool outlets. This will enable pool managers to be aware of any issues and potential hazards in the pool.

If the grilles are damaged or broken they can present a mechanical entrapment risk. If a swimmer gets their clothing caught on the grille, they may not be able to free themselves.

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Broken grilles can become an entrapment hazard by snagging swimmers clothing

If any grilles fail the conformity tests Commercial & Specialised Diving can fit specially designed anti-vortex grilles that prevent entrapment through suction or entanglement. Our divers can fit these quickly enabling your pool to be made safe without affecting the flow rates of your plant room filtration equipment.

Commercial & Specialised Diving have over 20 years’ experience servicing swimming pools across the nation. Contact our friendly sales team to find out more on or 01202 580007.