Why pre-screen plumbers before the trade test
The expensive failures in this trade are delayed. A joint that was not properly tested, a fall that is slightly wrong, a fitting mixed with an incompatible material: none of it shows on the day and all of it produces a callback and sometimes a damage claim. Plumbers worth hiring pressure test and can name a job that came back and why. A short screen asks for that, plus how they behave in an occupied house.
What actually matters when screening Plumber candidates
- 01
Hands-on competence
Check hands-on range: soldered and press-fit copper, MDPE and push-fit, soil stack work, unvented cylinder installs, combi swaps, power flushing, and bathroom first and second fix.
- 02
Safety discipline
Probe certification currency: Gas Safe registration and ACS categories, G3 unvented ticket, WRAS and Part L knowledge, plus practice on isolation, hot works permits, and asbestos awareness.
- 03
Fault finding
Test diagnostic method on no hot water, intermittent boiler lockout, low mains pressure, recurring leaks, and airlocks; listen for how they isolate cause before replacing parts.
- 04
Reliability and conduct
Assess van stock discipline, punctuality on booked slots, making good after chasing floors or walls, clear pricing before work, and handling a callback on their own install.
Pre-screening questions to ask Plumber candidates
12 questions grouped by what they test. Ask the same set in every screen and score answers on a consistent scale, or send them as an async video screen and compare answers side by side.
Systems they work on
4 questions01What types of plumbing systems are you most experienced with?
Listen forSpecific systems named with the property types they were installed in, and an honest scope of experience.
Every system claimed equally, or system types listed with no work described.
02Do you have experience with both residential and commercial plumbing?
Listen forThe differences named clearly, including scale, regulatory requirements and the constraints of working around occupied premises.
Both claimed with no distinction, or commercial experience that turns out to be a large house.
03Do you have experience installing and repairing water heaters?
Listen forInstallation described with the safety requirements covered, including relief valves and any gas registration needed.
Work described that requires a registration they do not hold, or safety devices not mentioned.
04Do you have experience with bathroom and kitchen fixture installation?
Listen forFitting quality described including sealing and falls, with a view on what causes callbacks in these jobs.
Installation described as connecting the fixture, or no awareness of what leaks weeks later.
Diagnosis not replacement
3 questions05Do you have experience diagnosing problems using camera equipment or other tools?
Listen forDiagnostic equipment used to find a cause rather than confirm a guess, with a fault it revealed.
Diagnosis by excavation or replacement, or no use of investigation tools before major work.
06Do you have experience with emergency plumbing situations?
Listen forContainment first with the cause found afterwards, and a realistic account of a call-out that went badly.
Emergency work described as fast repairs, or no job where the initial diagnosis was wrong.
07How familiar are you with different pipe types and materials?
Listen forMaterial compatibility understood, including where mixing metals or fittings causes failure over time.
Materials treated as interchangeable, or no awareness of corrosion between dissimilar metals.
Codes and safety
3 questions08Are you comfortable reading plans and working to building codes?
Listen forSpecific code requirements named, such as backflow prevention or venting, with an inspection they had to correct.
Codes described as guidance, or no failed inspection they can recall in substantial experience.
09Do you have experience with health and safety regulations related to plumbing?
Listen forWater hygiene and contamination risks understood, with isolation and testing performed before reinstating supply.
Supply reinstated without testing, or no awareness of contamination risk during works.
10Do you hold a valid plumbing licence and any additional registrations?
Listen forCurrent licensing named with any gas or specialist registration, and a clear line on work they cannot legally do.
Work described that requires a registration they do not hold, or licensing status left vague.
Conduct in a home
2 questions11Are you comfortable explaining technical details to customers?
Listen forPlain explanation of what is wrong and what it will cost, with options given rather than a single quote.
Work justified with jargon, or additional work added without explaining why it is needed.
12Do you clear up after work in a customer's property?
Listen forProtection put down before starting and the space left clean, treated as part of the job rather than a courtesy.
Cleanup treated as optional, or no mention of protecting floors and surfaces before work begins.
How to score responses
Score every candidate on the same four criteria immediately after the screen. At this stage you are shortlisting for panel interviews, not making the final call.
Hands-on competence
35%5Names specific installs (unvented G3, S-plan wiring, macerator runs) and describes pipe sizing and pressure testing without prompting.
Safety discipline
30%5Cites live registration numbers and ACS modules, and describes refusing or capping an unsafe appliance with an ID or AR warning notice.
Fault finding
20%5Walks a logical sequence (pressure gauge, flow test, manometer readings, fault codes) and cites a fault others had misdiagnosed and replaced wrongly.
Reliability and conduct
15%5Gives evidence of low callback rates, tidy handovers with commissioning paperwork, and returning to fix their own defect at no charge.
The expensive failures are delayed: a joint not properly tested, a fall slightly wrong. A one-way video screen asks about a job that came back.
Try it on HirevireScreening FAQ
Process basics
How long should a pre-screening round for a plumber take?
Ten minutes across eight to ten questions, answered async. Enough to establish the systems and property types they work on, test their diagnostic approach, and check licensing and safety practice.
Does the screen replace checking licences and insurance?
No. Verify licensing, gas or equivalent registrations and public liability cover directly with the issuing bodies. The screen establishes how they work, which no certificate demonstrates.
Evaluating answers
What is the strongest signal when screening a plumber?
A job that came back. Every plumber with volume has one, and the honest account of the cause and the fix tells you whether they diagnose or replace. Anyone with no callbacks has done fewer jobs than claimed.
How do I judge their conduct on site?
Ask what they do before leaving a customer's home. Good answers cover testing the work, explaining what was done and clearing up. Anyone who does not mention leaving the space clean will generate complaints.
Go deeper on this role
Sanat has been hiring since 2012 and watching the recruitment industry change up close ever since, and turned that screening process into Hirevire's video screening platform. LinkedIn
