Galvanised steel pipe

Galvanised steel pipe is a mild steel pipe coated with zinc to provide corrosion resistance, widely installed in UK plumbing from the 1900s to early 1960s. It was commonly used for cold water supply, gas piping and external waste runs across London terraced housing and interwar suburban development. The pipe is identifiable by its dull grey threaded joints and tendency to develop external surface rust where the galvanising has worn. Internally, galvanised supply pipework typically suffers progressive scaling and bore reduction over decades, leading to reduced flow at upper floor outlets. While safe to leave in place, galvanised supply pipes are normally replaced during refurbishment with MDPE or copper. The material is no longer used for new drainage installations under current Building Regulations Part H or Water Supply Regulations 1999.