I have brought one of these pools today, £30 8 foot by 3 foot, I have only ever brought in the past the smallest paddling pool ever and it last 2 days before I got rid of it, they fill me with such fear, because when my boys where 18 months old, a complete stranger to me but just down the road lost a 2 year old twin in a paddling pool drowning, Mum had 5 children and from what I read in the paper, they where all in the kitchen and she was sorting out their lunches/dinner, when she realised 1 was missing, it filled me with such dread, I knew how easy it was for me to get distracted by 1 of my twins and then be running about trying to find the other.
My boys are 7 now and I feel I have to let them have this type of fun, we are out all day and get in a 6pm, so it will just be 1 hour of supervision me thinks, well this pool took 3 hours to fill and at 11pm I gave up it is nearly there, about 10 mins later I heard a noise in the kitchen went through and found one of my twins in the garden, I just want to check it is full mummy!
he went to bed 3 hours ago, but obviously excited, so no I don't think you are unreasonable,
for alternative fun I used to use those slip and slides, risk a broken leg, but not life threatening but they don't last, water pistols and throwing cups of water at each other.
these pools can not be tipped out, just look at the filling time I took. also it says 6 years plus, and that leaning on the edge of the pool can led to collapse and injury, hat is a 14 month going to want to do if they can't get in?
but do talk to her about your concerns maybe she has a big superdooper baby prison (playpen) she uses in the garden, I did in both house and garden for the moment of the phone call, bell going, needing the loo, they where so big, I used them all the time, small children are so quick, it was safest