About us
Water Treatment Engineers is a New Zealand based consulting firm providing water treatment expertise to water suppliers.
We specialise in solving difficult problems and balancing operational requirements with project requirements. Our team is multi-disciplined with mechanical, chemical/process and electrical engineers.
We have experience in water treatment plant operation, plant optimisation, operational document development, process design, project delivery, troubleshooting and commissioning.
We have worked extensively with municipal water suppliers, small water supplies and industrial applications.
Water Treatment Engineers is based in Auckland and has a strong network of contacts within the water treatment industry including designers, contractors and equipment suppliers.
Key Highlights
Extensive Industry Experience
We pride ourselves on having hands-on practical experience to ensure that the solutions we provide are grounded in reality. Our team has worked on/with:
- Various water treatment processes from conventional treatment, ion exchange and reverse osmosis through to ultrafiltration, chlorination.
- Water Sources of varying qualities
- Clients from small to large
- Projects from small to large
- Many different roles throughout projects from concept design through to commissioning, handover and operation.
Client-Focused Approach
Our goal is to deeply understand the issues and requirements of our clients. It is our belief that, if we truly understand a client’s problem, then we can be confident that our solution will both meet and be proportionate to the problem. The Client-Focused Approach reduces the risk of us providing a solution that either does not resolve the issue or costs more than it should.
Health and Safety Excellence
At Water Treatment Engineers NZ, health and safety is at the forefront of everything we do. Our commitment to maintaining the highest standards of safety is demonstrated through our comprehensive approach to risk management.
Risk Management
At Water Treatment Engineers NZ, we believe that risk management is key to achieving successful outcomes for our clients. We employ flexible and effective risk assessment processes because, if risks are not well managed or understood, then even small projects can cause major headaches.
Key risk management techniques we use include:
- Gathering high quality information to inform the risk process. High quality information allows us to make meaningful decisions about risks.
- Engaging with the right people who have the appropriate knowledge/experience about the activity or design being assessed.
- Following structured processes that are sufficiently flexible to incorporate a wide range of risks.
Not proceeding when a risk is either not well understood or not well mitigated and taking the appropriate steps to manage the risk.
Meet the Team
Benjamin Demmer-Knight
Managing Director
BEngNZ, BE (Chemical & Material) (Hons)
Ben is a Water Treatment Engineer who has in depth operational understanding, experience on treatment plants of all sizes, has experience working on a wide range of projects and has extensive commissioning experience.
Ben specializes in projects that are complex, and that have a high level of interaction with operations. He is able to provide support throughout a project from Concept through to Handover and Operational support.
SPECIALISATIONS
- Plant Optimization
- Project Integration with Operations
- Functional Descriptions & SOP development
- Troubleshooting
- Detailed process design
- Project and contract management
- Construction supervision
- Commissioning
- Preparation of installation specifications
PROJECT EXPERIENCE
Taumata Arowai Instrument Upgrade – 2023
Watercare completed a project for upgrading all their sites to meet the updated Taumata Arowai Drinking Water Quality Assurance Rules (2022). It consisted of installing additional compliance analysers required under the new rules. The project consisted of 4 stages based on priority.
Ben’s role in the project was to provide project support and engineering services through stages 2-4. Over 60 water quality analysers were installed across 13 sites requiring a significant amount of collaboration with many stakeholders throughout operations. Ben’s specific set of experience allowed for this project to proceed smoothly with minimal push back or issues.
Snells Water Treatment Plant Upgrade – 2023
Watercare upgraded the Snells Water Treatment Plant (WTP) with permanent AVG filters and a temporary clarifier through a Design-Build process. The upgrade was designed to mitigate the risk of aquifer contamination due to drilling nearby.
Ben had three roles in the project: Design Project Manager, Project Engineer for Construction and Commissioning Engineer. Ben’s operational experience allowed for streamlining of the design process and a smooth handover process.
Muriwai WTP Recommissioning – 2023
During Cyclone Gabrielle landslips caused significant damage to Watercare’s Muriwai Water Treatment Plant. Watercare initiated a project to repair and recommission the plant. Several parallel upgrades were completed including a PLC upgrade requiring re-testing of the entire software.
Ben’s role was to carry out the pre, cold and hot commissioning of the plant. The process was challenging as there was an ongoing landslip risk that required careful health and safety management.
Hibiscus Coast Boost Pump Station – 2022-2023
Watercare completed a new Booster Pump Station supplying 19 MLD to the Whangaparoa region of Auckland. The pump station is designed to increase the flowrate and boost the pressure of water entering the peninsula via two Watermains.
Ben had the role of Commissioning Engineer working alongside the internal Watercare Commissioning Team. Through a careful risk based approach and collaboration with operations, over 14 km of a live, large bore pipeline was flushed without generating a water quality issue for the public.
Waikato 50 Water Treatment Plant – 2021
Watercare completed a fast-tracked 50 MLD water treatment plant. The system uses membranes, BACs and Chlorination to treat water supplied by a Floating Pump Station in the Waikato River. Ben’s role in the project was to provide commissioning support.
Warkworth Wells WTP – 2018-2019
Watercare completed a project for the replacement of an ageing and high risk surface water treatment facility with a new higher capacity ground water treatment plant. The works included constructing an entirely new treatment plant designed to treat iron, manganese and provide disinfection for the Warkworth region.
Ben’s role throughout the project was as the operations main point of contact throughout the design and construction phases and formed a part of the commissioning team. Ben was employed by Watercare at the time of this project.
Auckland Council Small Water Supply Upgrades 2019 – 2021
Auckland Council completed upgrades to 12 small water supplies in a series of projects for community halls, a Marae, and regional parks. Water sources were 4 bore supplies and 8 rain water treatment systems. Acqua by Davey supplied and installed pre-fabricated Water Treatment Plants for each of these sites.
Ben had multiple roles within these projects which included proposal development, pricing, preliminary design, detailed design, project management, documentation and commissioning of each system. Ben was employed by Acqua by Davey at the time of these projects.
Teokotai Ruland-Marsters
Senior Water and Wastewater Engineer
Principal Mechanical Engineer
BEngNZ, BE (Mech)
Teo is a highly experienced Mechanical Process Engineer with over 15 years in the water and wastewater industry, specializing in the full lifecycle of wastewater treatment systems—from design through to construction oversight, commissioning, and operational optimization.
Teo specializes in complex projects that require a deep understanding of the entire process, including critical support services. He is able to provide support throughout a project from concept through to handover and operational optimisation.
SPECIALISATIONS
- Plant Optimization and Troubleshootin
- Project Integration with Operation
- Functional Descriptions & SOP development
- Detailed process designProject and contract management
- Commissioning
PROJECT EXPERIENCE
Tokoroa WWTP digester upgrade 2020-2021
An upgrade of Tokoroa WWTP aimed at enhancing sludge treatment and energy recovery was completed which added a new sludge reception tank, digester sludge pump station and bio-gas system.
Teo was the Lead Design Engineer responsible for the detailed design while also providing construction and commissioning support throughout the project. Teo’s extensive design and practical experience ensured the seamless integration of the various systems into the existing WWTP.
Watercare Rosedale WWTP upgrade 2015-2021
Watercare carried out an upgrade of the Rosedale wastewater treatment plant aimed at increasing treatment capacity and improving operational efficiency.
The project included:
- New Primary Sedimentation Tanks (PSTs)
- A new Modified Ludzack-Ettinger (MLE) tank
- Expansion of the blower system
- A new anaerobic digester
- Implementation of a new biofilter system
- Upgrade of the sludge pump station
- Expansion of the sludge dewatering facility.
Teo provided design leadership, construction oversight, and commissioning support to ensure the successful integration of these upgrades into the existing plant operations.
Waste to Gold (TERAX), Hydrothermal Deconstruction Plant 2015-2016
Rotorua District Council initiated a project to integrate the Waste to Gold (TERAX) Hydrothermal Deconstruction Plant into the Rotorua Wastewater Treatment Plant.Teo acted as Lead Design Engineer with primary responsibility for the balance of plant integration, overseeing the development of the pilot scheme through to commercialisation and full integration within the existing wastewater treatment infrastructure.
Worley led the design and delivery of the high-pressure process components, while Teo focused on ensuring seamless integration of utilities, mechanical and process interfaces, controls, civil tie-ins, and operational alignment with the existing plant. This included the integration of energy recovery and waste heat streams into the broader treatment process to optimise overall plant performance.
Rotorua WWTP MBR Upgrade 2016-2017
A project for the Rotorua WWTP was completed upgrading an existing activated sludge system with a side-stream MBR to a full MBR system, ensuring compliance with the highest discharge standards suitable for discharge into Lake Rotorua.
The design included a cascading discharge system with urban realm features such as public walking and mountain biking tracks. Cultural treatment features prescribed by local Māori were integrated before the treated effluent was discharged into Lake Rotorua.
Teo served as the Lead Design Engineer through the conceptual and preliminary design. Teo’s engineering experience and deep cultural ties ensured a solution that satisfied technical and stakeholder requirements on a challenging brownfield project with potential for environmental and cultural impacts.
Taupo WWTP and irrigation upgrade 2008-2010
The Taupo wastewater treatment plant and irrigation system underwent a series of improvements to increase its capacity in response to regional growth and to meet more stringent discharge limits. The upgrades included enhancements to the digesters, solids handling, trickling filters, terminal pump stations, primary sedimentation tanks, boiler systems, and the View Road irrigation scheme.
Teo was involved in all aspects of the project and was based in Taupo for an entire year on this project. Teo’s responsibilities included conducting site investigations, overseeing construction activities, commissioning assistance, developing operation and maintenance manuals and standard operating procedures.
Additionally, Teo conducted a feasibility study for a cogeneration power and heat system utilizing biogas by- products and optimized the sludge handling facility to improve dewatered sludge quality for use in composting and earthworm farming.
The project successfully modernized critical infrastructure while balancing cost-effectiveness and regulatory compliance, ensuring the long-term sustainability of the Taupo wastewater treatment plant.
Wastewater treatment plants throughout New Zealand
Teo has contributed to the development and optimization of many wastewater treatment plants across New Zealand, engaging in various stages including concept, preliminary, and detailed design, design-build support, construction observation, commissioning, and the preparation of key documentation and deliverables.
His involvement has spanned the creation of Piping and Instrumentation Diagrams (P&IDs), general arrangement drawings, 3D models, equipment schedules, operation and maintenance manuals, equipment specifications for procurement, asset capitalization spreadsheets, commissioning plans, HAZOP studies, technical reports, options investigations, condition assessments, and construction contracts.
Teo has worked on the following treatment plants:
- Pukekohe SBR WWTP
- Army Bay SBR WWTP
- Kinloch SBR WWTP
- Turangi MBR WWTP
- Rotoiti MBR WWTP
- Helensville Pond WWTP
- Mangere AS WWTP
- Whangarei AS WWTP
- Kerikeri SBR WWTP
- Snells Beach WWTP
- Wanaka SBR WWTP
His expertise in wastewater treatment processes and infrastructure has enabled these facilities to achieve compliance, operational efficiency, and long-term resilience.
Ryan McMahon
Principal Electrical Engineer
BE (Elec) (Hons)
Ryan is a highly experienced Infrastructure Electrical Engineer and Project Manager with 20+ years in plant automation, electrical design, and large-scale infrastructure projects. Skilled in overseeing projects from concept to completion, ensuring compliance, efficiency, and budget control.
Ryan is a strategic problem-solver with a focus on risk management, safety compliance, and sustainable energy solutions. Adept at working with executives, stakeholders, and engineering teams to drive innovation and deliver high-impact projects.
SPECIALISATIONS
- Electrical & Control Systems Engineering
- Project & Site Management
- High Voltage (HV) & Low Voltage (LV) Systems
- PLC & HMI Programming
- Contract Administration (NEC3, 3916, 3910)
- Safety & Compliance (AS4024, H&S Risk Management)
- Electrical CAD, Circuit Design & Distribution Systems
- SCADA, PLCs, VSDs, & Instrumentation
- High Voltage (11kV-22kV) Systems & Load Management
PROJECT EXPERIENCE
Mangere WWTP BNR Upgrade 2016-2018
Watercare completed a significant upgrade of Mangere WWTP to improve nutrient removal through the addition of the BNR process. The upgrade included the addition of a new IPS2/BNR 11kV substation.
Ryan was the Electrical lead responsible for oversight of the BNR electrical discipline. Ryan also acted as project manager for the new IPS2/BNR 11kV substation. Ryan’s extensive practical experience ensured the seamless integration of the electrical systems into the existing WWTP.
Mangere WWTP Digester Electrical Upgrade 2011-2013
- New 11kV supplies via multiple ring main units and 11kV/400V transformers.
- New downstream 400V power distribution centres and unitised motor control centres.
- Significant civil works to modify an existing boiler room into a new 400V switch room.
Ryan’s role as project engineer included investigation, capital submission, electrical design verification, project management and final commissioning.
Rosedale WWTP Digester Electrical Upgrade 2016-2018
Watercare upgraded the electrical supply to the Rosedale WWTP through the addition of a new Vector feeder, 11kV substation and new site 11kV ringmain.
Ryan was the electrical lead for the project and his extensive electrical experience enabled the seamless integration of new high voltage power supply to the site.
Taharoa Stage 2 Mine Expansion 2014-2015
This project was developed to enable New Zealand Steel’s Taharoa Mine site to expand export capability to support a second new iron ore bulk carrier and to increase mine output from 900kt to 2.7Mt. New dry mining equipment was introduced as well as a new processing plant.
As engineering manager, Ryan developed a multi discipline team to assist in plant construction completion, plant commissioning and handover.
RESPONSIBILITIES
- Site construction management of up to 50 contractors daily during construction
- Design changes required to achieve project objectives
- Control Philosophy and FD development
- Managing multi-platform PLC software development and control room SCADA development
- Energisation and commissioning plan development. Commissioning of all new plant
- Operator job allocation, training and eventual hand over
- Capex development to secure addition mining and processing plant to support original project objectives
- Contract administration and management
- Management of all site Health and Safety for construction, commissioning and initial production period
- Provided detailed schedule and cost information to senior management periodically
- Provided regular updates on project activities to local Iwi
ACHIEVEMENTS
- Zero Harm and only minor incidents recorded
- At time of hand over, new plant operating 24/7 with utilisation at that stage up to 80% and increasing. Production from plant in line with original project objectives
- Completion and commissioning of all stages as per project schedule. Primary concentrate iron ore stockpile increased from 180k tonnes to the senior management target of 1M tonnes at time of second ships maiden voyage
Waikato Freight Hub Development 2018-2023
The Port of Auckland completed a new 33-hectare site development in Horotui region of Waikato. New public road to service site, planning for future rail sliding and new tenant warehouse. The project included significant coordination with Waikato Electric Lines company (WEL networks) regarding:
- Entire site load plan, for each new development/lot
- Kohia Road construction by POAL including Kiwi Rail overbridge. Design co-ordination for service trenches installed by POAL contractors and approved by WEL Networks
- New 11kv/400V 300KVA transformer and connected feeder to existing network ~1km away
- Cable route via newly installed service trenches. Transformer to service new OCD ICP via new Network Connection Agreement,
- UFB installation via WEL networks data division.
Waitemata Port Site – Southern Reefers Installation 2018-2023
Port of Auckland upgraded the Waitemata Port Site with a new HV ring main to support the new Southern Reefers gantries. Ryan was responsible for the design and implementation of the new HV ringmain and 4 new 750KVA transformers to supply the gantries.
New Zealand Steel 2004-2011
During this role Ryan was contracted to the New Zealand Steel Engineering Services. Ryan was responsible for design and implementation of turnkey electrical capital projects, process controls, reliability strategies and process improvements.
RESPONSIBILITIES
- Costing & management of capital projects
- Preparation of CAPEX applications and presentation of business cases
- Liaise with international and local OEM machine builders, suppliers and contractors
- Design, selection, specification, installation & commissioning of Electrical and Instrumentation control systems, AC motor drives, hydraulic and pneumatic controls for purpose-built equipment and improvements
PROJECTS
- Site wide Fire Alarms Upgrade
- Lead Electrical – Mining, Tailings Line Upgrade
- Lead Electrical – Mining, Pre-Slurry Pumping, Attritioner Installation
- Project Manager – Rolling Mills Tuxedo Fibre Optic Network Installation
- Electrical Support – Pipe Mill Transport Section Pneumatic Upgrade
- Electrical Support – Medical Centre Electrical Supplies
- Lead Electrical – Melters HVAC Upgrade
- Lead Control System Engineer – Melters Tapping Floor Upgrade
His expertise in electrical engineering and project management has enabled these facilities to achieve compliance, operational efficiency, and long-term resilience.