Portugal has no equivalent to France's loi piscine. Whatever safety provision a private pool has is whatever the previous owner chose to install, which is often nothing.
Sources: France loi piscine (loi n.º 2003-9); APSI & INEM drowning-prevention data. The "more than half of pools are illegal" claim circulating online is an industry estimate (Fórum da Casa), not an official statistic. · InspectOS