What are regulations require that shower heads when not constrained by their permanent or sliding attachment or not fall within what distance of the maximum water level of either a bath or shower tray?

Regulations typically require that shower heads, when not constrained by their permanent or sliding attachment, must not fall within a certain distance, usually set at a minimum of 25 mm (1 inch), from the maximum water level of either a bath or shower tray. This is to prevent the risk of backflow and ensure proper drainage. The specific distance may vary depending on local Plumbing codes, so it's essential to consult relevant regulations for precise requirements in a given area.