Can any one help me with this please? What are the rules on the number of lifeguards required x number of people? Is there a ratio guideline for this or is it simply down to what my RA tells me? Many thanks in advance Dave

As Chas has said, 179 is as good a place to start as any and I think that it has recently been updated. But, as you have already said yourself, it is down to a RA that is based on the individual circumstances at your pool, bearing in mind it's size, shape, depth, activities, ages, abilities etc. In that respect 179 is very much only a starting point. ISRM (I think now CIMSPA) also have guidance and advice on this as well.