on this link, the institudo estadual do ambiente (inea)provides the suitability of several beaches in niterói, including praia de jurujuba that can be used to guess water quality at praia do cáis since they are very close to each other.

constantly updated, the red flags mean that swimming is not advisable, green flags mean waters are clean, and yellow flags suggest using own judgment.

any of rio's beaches may have polluted waters within 24 to 48 hours following heavy rains.