Keeping Your Swimmers Alive – Are You Responsible?

Health and Safety in swimming pools is vital, yet there are still around 10 deaths every year caused by drowning.  Each of these is a tragedy and many can easily be avoided.

One of the biggest risks to swimmers is entrapment.  A swimmer held underwater will invariably drown.

So what are the causes and what are the solutions?

Excessive Suction

Outlets have a large volume of water flowing through them in order for the water to be filtered by the plant equipment.  This creates suction around the outlet openings in the pool.  If the flow rate is too high or the sump grilles poorly designed, it could lead to someone being sucked onto the grille and unable to free themselves.  This is a major hazard, especially when the pool only has a single outlet.

There should be at least two active outlets per suction line.  These should be far enough apart to prevent a body being trapped.

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 forcefully suck in hair.  The spinning vortex caused around the suction pipe creates an underwater whirl pool which can entangle hair sucked through the grille. If this were to happen the swimmer may become trapped.

Hair entrapment injury

To overcome this problem, the recommended maximum flow rate is 0.5m/s, ideally 0.3 m/s.

Special oversized anti- vortex grilles can be retro-fitted over existing outlets and sumps.  These have water inlets on the sides as well as the top ensuring the outlet area cannot be blocked.  The larger surface area reduces the suction over the grille area without affecting the flow rate.

Suction injury to torso


According to BS EN:13451 grille openings should be less than 8mm to avoid entrapment of fingers.  A simple probe test can be used to determine if grilles conform to this safety standard.  If grilles have holes which are 8mm-23mm, they will pose an entrapment risk and should be changed for grilles which conform to the British Standard.   Children are particularly vulnerable as they are often inquisitive in swimming pools and will explore the environment with no concept of the dangers that may be present.

 Wave Machine Chambers

Wave machine chambers should be securely guarded against swimmers from entering the chamber area.  The guard rails should be 100mmm apart or less and constructed of rounded bar to help prevent limb entrapment.

Moving Floors and Bulkheads

Moving floors and bulkheads should be checked regularly to ensure there are no gaps around the edges greater than 8mm which could lead to entrapment.  Many moving floors and bulkheads have guide rollers on the wall which can be adjusted in order to maintain a safe gap.  Flexible rubber gaskets can be used to fill any gaps between the edge of the moving floor and the wall.  Bulkheads should be sealed to prevent a swimmer from gaining access and becoming trapped inside.


A child with a trapped arm



Where slides enter the water, the gap between the slide structure and the wall may present an entrapment danger to slide and pool users which could lead to injury or death.

Our Solution

If you are unsure about the safety of your swimming pool, we will conduct an underwater health and safety audit within the pool and offer solutions to any entrapment hazards found.

Diver inspecting an inlet diffuser on a safety inspection.

It is better to be safe than sorry.

Commercial and Specialised Diving are experts in swimming pool safety.  We can survey and remedy any health and safety issues regarding your swimming pool.

If you have a project that requires our help, please do not hesitate to give us a call on 01202 580007.