You will need to understand your:

Two dead end pipes extruding from a wall
Dead/blind end – a redundant length of pipe, closed at one end, through which water cannot flow.
Thermostatic Mixer Valve
Thermostatic Mixer Valves (TMVs) – these blend hot and cold water to reduce the temperature where a scald risk is present.
Pipe with multiple outlets, highlighting first and last outlet
Sentinel outlets – the nearest and furthest/last outlets from hot and cold water cylinders and tanks.
Dead leg pipe highlighted in a pipework schematic drawing
Dead leg – a pipe leading to an outlet through which water flows but the outlet is unused/rarely used.
Updated 2021-02-19