I'm not going to start bawling about people getting microscopic amounts of breastmilk on them... there are MUCH MUCH WORSE things in swimming pools... If the thought of breast milk bothers anyone, they probably shouldn't be swimming in public pools at all
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However for that very same reason, I'd say feeding in the pool is probably not a very good idea. Not very hygienic for the child? And surely a drowning hazard, too?
Also I guess on the most basic level; NO ONE is allowed to eat or drink in most pools. It's not really discrimination if that applies to babies too. It's inclusion, if anything.