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.
How plumbing quotes work
Describe the job, including whether it's an emergency, a planned repair, or a full installation, and mention access — under a suspended floor is very different from behind fitted units. Plumbers use this for an initial estimate; the final price is usually confirmed once they've seen the fault or the space in person.
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.
What's involved in a bathroom refit
A full bathroom refit usually means removing the old suite, checking and often replacing the pipework behind it (since it's rarely accessible again once tiled over), first-fix plumbing before tiling, then second-fix (taps, shower, toilet cistern) once the room is finished. Waterproofing (tanking) around a shower area is a step worth confirming is included, not assumed.
What WaterSafe registration means
WaterSafe is the umbrella body for the UK's Approved Contractor Person schemes (including APHC, CIPHE, WIAPS and SNIPEF). A WaterSafe-approved plumber has been assessed on their knowledge of the Water Fittings Regulations, which exist to stop poor installation work or substandard products contaminating the drinking water supply — not just general plumbing competence.
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.
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.
Boiler pressure and heating faults
Most combi boilers run best between 1 and 1.5 bar of pressure — too low and the heating cuts out, too high and the pressure relief valve can discharge. A plumber checking a heating fault will usually look at pressure, check for trapped air in radiators (bleeding), and check the pump and diverter valve before assuming a full boiler fault.