Water ingress testing is conducted to measure and verify the resistance of fluids entering a product or damaging the outer surface or enclosure. The product type and use cases determine the type of water ingress test required - rain and splash testing are essentially harsher water ingress tests than drip testing.

Products placed within a rain testing chamber are sprayed with water jets at particular angles and flow rates as specified by the standard being tested for.

Water ingress testing is standardized by IEC 60529 in conjunction with particle ingress standards. Products are given an IP rating that combines the levels of ingress protection that a product is capable of achieving. IPX5 is tested with nozzles spraying at 12.5 L/min through 6.3 mm diameter nozzles from a distance for 2.5 to 3 m. Slightly stronger than IPX5, IPX6 is tested at 100 L/min from 12.5 mm diameter nozzles from the same distance. IPX9K is a specialized test that uses 80 to 100 bar (1160 to 1450 psi) jet pressure at 80°C. The test conditions of this chamber are in accordance the UL1589 specifications.