Why pre-screen water technology specialists before the interview
Treatment processes look deterministic on a flow diagram and behave differently in a plant. Membranes foul faster than the design assumed, biofilm establishes in dead legs, and an upset at three in the morning has to be resolved by whoever is there. Specialists worth hiring have handled one. A short screen asks about a plant upset and how they worked out the cause.
What actually matters when screening Water Technology Specialist candidates
- 01
Technical depth
Check command of water chemistry: Langelier and Ryznar indices, RO membrane fouling versus scaling, chlorine dioxide dosing, ion exchange regeneration, and ASHRAE 188 or L8 legionella requirements.
- 02
Work that shipped
Ask for commissioned systems: RO or ultrafiltration skids, cooling tower programmes, ZLD or effluent plants, with capacity, recovery rate and chemical cost per cubic metre delivered.
- 03
Diagnosis under uncertainty
Probe how they traced a problem: sudden conductivity spike, boiler carryover, microbial counts breaching limits, or differential pressure climb across a membrane train.
- 04
Working across the org
Assess dealings with plant operators, EHS teams, chemical suppliers and regulators during audits, water risk assessments or discharge permit renewals.
Pre-screening questions to ask Water Technology Specialist 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.
Plants they worked on
3 questions01Can you describe your experience designing and maintaining water treatment systems?
Listen forPlants they designed or operated with capacity and application stated, and their own responsibility.
Experience described at consultancy level only, or no plant they were responsible for.
02Have you worked on projects involving wastewater management or reuse?
Listen forTreatment to a defined reuse standard, with the quality risk of reuse understood and managed.
Reuse treated as a simple additional step, or the quality requirements of the end use unclear.
03Can you describe a challenging problem you solved in water technology?
Listen forA real operational problem such as fouling or an upset, traced to a cause and corrected properly.
Problems described as budget constraints, or issues resolved by increasing chemical dosing.
Processes understood
3 questions04Which water purification technologies are you most familiar with?
Listen forSeveral technologies with the water quality each suits, and the choice justified by feed conditions.
One technology proposed for every application, or feed water quality not considered.
05Can you explain reverse osmosis and where it is appropriate?
Listen forPretreatment requirements and fouling explained, with recovery and reject disposal both addressed.
Membranes proposed without pretreatment, or concentrate disposal not considered at all.
06What experience do you have with desalination processes?
Listen forEnergy cost and brine management treated as central constraints rather than downstream problems.
Energy consumption not quantified, or brine discharge described as a permitting detail.
Quality and safety
4 questions07What experience do you have with water quality testing and analysis?
Listen forSampling and testing performed with the parameters that matter for the application understood.
Testing left entirely to a laboratory, or results accepted without checking sampling method.
08How do you manage microbial control in water systems?
Listen forBiofilm and dead legs understood as the real risk, with disinfection residual maintained and monitored.
Disinfection assumed sufficient, or system design that creates stagnant sections.
09How do you ensure safety when working with treatment chemicals?
Listen forIncompatible chemicals separated, with confined space and gas release risks treated seriously.
Chemical handling described casually, or gas generation from mixing not identified as a hazard.
10How would you handle an unexpected breakdown at a treatment plant?
Listen forWater quality protected first, with a defined response including stopping supply where necessary.
Production prioritised over quality, or no clear trigger for taking a plant offline.
Can cost the work
2 questions11Which regulatory and compliance standards are you familiar with?
Listen forApplicable standards known for the sector, with monitoring and reporting obligations understood.
Standards unfamiliar, or compliance treated as somebody else's responsibility entirely.
12Have you been involved in cost estimation or budgeting for treatment projects?
Listen forWhole-life cost estimated including chemicals, energy and membrane replacement, not capital alone.
Capital cost quoted without operating cost, or consumable replacement omitted from budgets.
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.
Technical depth
35%5Explains cycles of concentration, silt density index limits and inhibitor selection with numbers, not vendor slogans or generic chemistry.
Work that shipped
30%5Names specific plants and quantified outcomes: recovery lifted, blowdown cut, membrane life extended, discharge consents met.
Diagnosis under uncertainty
20%5Walks through sampling, jar tests, autopsy of a fouled element and data trending before naming a root cause.
Working across the org
15%5Describes training operators on dosing logs and negotiating corrective actions with site management and inspectors without escalation.
Membranes foul faster than the design assumed and upsets happen at three in the morning. A one-way video screen asks about that.
Try it on HirevireScreening FAQ
Process basics
How long should a pre-screening round for this role take?
Fifteen minutes across eight to ten questions, answered async. Enough to establish plants they worked on, test their process knowledge, and check quality, safety and costing experience.
Does the application sector matter?
Yes. Municipal drinking water, industrial process water and wastewater have different regulatory regimes and quality targets, and experience in one does not transfer straight into another.
Evaluating answers
What is the strongest signal when screening this role?
A plant upset they resolved. Specialists with operating time describe the parameters they checked and the cause they found. Anyone answering only in process theory has not run a plant.
How do I judge their safety awareness?
Ask about chemical handling. Real answers cover incompatible chemicals, confined spaces and gas risks specifically. Anyone treating treatment chemicals casually will cause a serious incident eventually.
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
