My children swim really well. Surely they can be treated differently from those who cant swim?
Yes they can! Pool operators are encouraged to take account of swimming ability and to maximise access to pools.
Clearly there are practical limitations to assessing ability on a case-by-case basis, but there are schemes for certifying good ability.
For example, the ASA and ISRM (the leading national professional body for sport and recreational management in this country) have a Safe Swimming Award. It is like a passport to swim and certifies a level of swimming ability and water confidence.
To get the award a child must jump into water at 1.5metres or more so that his or her head goes right under - or in shallow water hold a submerged mushroom float for 10 seconds. The child must also swim 50metres in under two minutes and tread water for a minute without a break.