ISO 13009:2015 establishes general requirements and recommendations for beach operators that offer tourist and visitor services. It provides guidance for both beach operators and users regarding the delivery of sustainable management and planning, beach ownership, sustainable infrastructure and service provision needs, including beach safety, information and communication, cleaning and waste removal.
Interesting ISO13009 doesn’t cover water quality, so you may have a pretty looking sandy / aggregate beach, with a bit of signage and an organised beach cleaning operation i.e. a couple of bins and coconut branch beach umbrellas, and a couple of indigenous natives selling the local brew. Yet in terms of water quality standards, much is driven by The World Health Organisation (WHO), which in recent days has lost a shedload of funding.
As a former active member of the SAS in the UK, that's Surfers against Sewage incase there's any confusion, I wouldn't even dip my toes in the local water.