First fix and second fix plumbing
On a new build or extension, "first fix" is running pipework through walls and floors before they're closed up; "second fix" is fitting the visible taps, radiators and appliances once decorating is done. Timing this with other trades on site matters — pipework needs to be pressure-tested before it's covered over, not after.
Understanding the labour vs materials split
Materials — pipework, fittings, a new boiler or bathroom suite — are often a smaller share of a plumbing quote than labour, particularly for jobs involving lifting floors or chasing walls. If a quote looks unusually cheap, check whether it specifies the same brand/quality of fittings as a competing quote, not just a lower labour rate.
Plumbing in older and period properties
Older properties sometimes still have lead or galvanised steel pipework, which can affect both water quality and pressure, and original layouts weren't designed around modern demand for multiple bathrooms. A plumber working on a period property will often check what the existing pipework is made of before quoting for anything beyond a like-for-like repair.
Three steps to hiring the right plumber
First, check they're registered with a WaterSafe scheme (or Gas Safe too, if the job needs it) and ask for the registration number. Second, get a written quote that separates labour from parts. Third, ask what happens if the job uncovers a bigger problem — a good plumber will tell you before continuing, not after.
Combi vs system vs conventional boilers
A combi boiler heats water on demand with no separate tank, suits smaller properties with one bathroom. A system boiler uses a hot water cylinder but no cold water tank, better for higher demand. A conventional (regular) boiler uses both a cylinder and a tank, common in older properties and useful where mains pressure is poor.
Common plumbing myths, busted
"A dripping tap is just cosmetic" — left long enough it wastes real water and can damage the fitting further. "Any handyman can fit a boiler" — boiler work involving gas connections legally needs a Gas Safe engineer, not just a plumber. "Bleeding a radiator fixes all heating faults" — it only helps with trapped air, not pressure or pump issues.
Background checks and identity verification
Before booking, it's worth checking a plumber's trading history and identity, not just their registration — a landline or verifiable business address and reviews referencing specific jobs are stronger signals than a mobile number and a van sign alone.
When plumbing work needs a Gas Safe engineer instead
Plumbers can install and repair most water systems, but any work on a gas appliance or gas pipework — a boiler, a gas fire, a gas hob — is illegal for anyone who isn't on the Gas Safe Register, by law. If a job involves both plumbing and a gas connection (moving a boiler, for example), check whether your plumber is also Gas Safe registered before booking.