Cover image: AI-generated illustration of an SWRO facility - not a photograph of the former client’s installation.
Disclaimer and Acknowledgement
This article is intended for general technical awareness and knowledge sharing. It draws partly on my consultancy experience supporting a client with interests in construction and desalination towards ISO 9001 certification.
I have not personally observed a working installation using the approach informally described as “slow-boiling” desalination. References to that approach reflect general technical principles and applicable requirements, rather than firsthand verification of an operating unit.
This article does not assess project investment costs, commercial feasibility, water sales or selling prices. Any illustrative electricity-cost calculations are included solely to explain the calculation method and should not be interpreted as actual tariffs, total production costs, quotations or commercial projections.
The discussion does not replace project-specific engineering assessments, regulatory approvals or verification of water and recovered-salt quality for their intended use.
I also extend my thanks to the subject matter experts who prefer to remain anonymous for their valuable input and technical insights.
Water security is also business continuity.
For factories, power stations and mining operations, an interruption in water supply can affect production, equipment, product quality and contractual commitments.
Seawater Reverse Osmosis (SWRO) offers coastal industries an alternative source of freshwater, potentially reducing their dependence on rivers, groundwater and municipal treated-water supplies.
The main focus of this article is SWRO.
1) HOW DOES IT WORK
SWRO uses pressure to drive water through semi-permeable membranes, separating seawater into a low-salinity product stream, called permeate, and a concentrated salt stream, called brine. It operates through membrane separation rather than boiling and condensation.
Diagram 1: Simplified SWRO treatment process
llustrative process only. The treatment configuration depends on seawater characteristics and the required product quality.
Pretreatment protects membranes against fouling and damage. Energy-recovery devices recover hydraulic energy from the pressurised brine stream, reducing pumping demand. The concentrated stream still requires appropriate management.
2.0 CAN IT SUPPORT INDUSTRY
Municipal treated water remains a valuable supply. However, industrial processes may require water specifications that differ from drinking-water requirements.
SWRO can provide an alternative feedwater source, with additional treatment selected for each application.
Table 1: SWRO and its application to various industries
RO is used in boiler-feedwater and semiconductor water-treatment systems. However, SWRO permeate is not automatically boiler-ready or ultrapure water. Further purification and conditioning must meet the relevant equipment and process specifications.
The wider benefit is supply diversification. Where industry can use a suitable alternative source, it may reduce demand on freshwater resources shared with surrounding communities.
Chile provides a practical example. BHP reports that Escondida ceased groundwater withdrawals for operational water supply in 2019 and has sourced its operational water withdrawals from desalinated ocean water since FY2020. Its infrastructure uses reverse osmosis and pumps desalinated water inland to the mine.
3.0 EXAMPLE - WATER OUTPUT AND ELECTRICITY DEMAND
The following calculations illustrate the relationship between feedwater, recovery, product water and electricity consumption.
These are assumed values for explanation, not plant design criteria, a quotation or a performance guarantee.
Table 2: Assumed Values
3.1. Permeate Production
Permeate = Feed × Recovery = 1,000 × 0.45 = 450 m³/day
This is equivalent to 450,000 litres per day, before downstream treatment losses and plant service-water consumption.
3.2. Brine Production
Brine = Feed − Permeate = 1,000 − 450 = 550 m³/day
This simplified balance excludes pretreatment backwash, chemical-cleaning waste and other side streams. Actual intake and waste-management requirements must include them.
3.3 Electricity Demand
Daily electricity = Permeate × Specific electricity consumption = 450 × 3.5 = 1,575 kWh/day
The assumed energy figure must represent a clearly defined system boundary. Additional treatment or long-distance pumping may increase overall consumption.
3.4. Electricity cost
Daily electricity cost = Electricity demand × Electricity rate = 1,575 × RM0.40 = RM630/day
Electricity cost per cubic metre of permeate: RM630 ÷ 450 = RM1.40/m³
This is electricity cost only. Total water cost must also include capital recovery, financing, membranes, chemicals, labour, maintenance, testing, residuals management and distribution.
If all 450 m³/day were suitable for an industrial duty and displaced an equivalent municipal-water demand, the theoretical substitution over 30 operating days would be:
450 × 30 = 13,500 m³
Actual substitution would depend on plant availability, demand, storage and net usable output.
4.0 CAN DESALINATED SEAWATER BE CONSUMED?
Yes, properly treated and verified desalinated seawater can become safe drinking water.
Salt removal is one part of the process. Potable supply also requires control of chemical and microbial risks, appropriate post-treatment, protected storage and distribution, and compliance with applicable drinking-water requirements.
WHO guidance addresses these risks through a water safety plan approach. It also highlights stabilisation or remineralisation to reduce the corrosiveness of desalinated water, and the need to assess substances such as boron that may require particular treatment attention.
Diagram 2: The intended use determines the treatment pathway
Singapore’s NEWater is a separate source: it is produced from treated used water and is extensively used by industry. This distinction matters when comparing seawater desalination with water reclamation and reuse.
6.0 APPLICATION OF ISO 9000 SYSTEM
Different standards address different aspects of the operation.
ISO 13205 and ISO 23446 are technical references with different scopes. As of November 2026, ISO 23446:2021 remains published and is under systematic review; the review does not itself create a replacement edition.
An ISO 9001 certificate supports confidence in the organisation’s management system. It does not, by itself, establish that every batch of water is safe to drink. Product conformity still requires defined acceptance criteria, effective controls and verified results.
7.0 BOILERS AND JKKP
The connection with boilers can arise in two ways: SWRO water may undergo further treatment for use as boiler feedwater, or a separate thermal desalination system may use steam to evaporate seawater.
In Malaysia, the boiler and associated equipment must be assessed against Jabatan Keselamatan dan Kesihatan Pekerjaan (JKKP/DOSH) requirements.
For thermal systems sometimes described informally as “slow boiling,” the heating rate does not determine the legal classification. The equipment’s design, pressure conditions and heating arrangement must be examined.
Under the Occupational Safety and Health (Plant Requiring Certificate of Fitness) Regulations 2024, a steam boiler involves a closed vessel generating steam above atmospheric pressure. JKKP also defines pressure vessels as closed containers operating above or below atmospheric pressure.
A vacuum evaporator should therefore be assessed for applicable pressure-vessel requirements and exclusions. A steam boiler supplying heat to that evaporator may require a separate assessment.
For equipment classified as a regulated steam boiler, key requirements include:
Required design verification and installation approval.
Inspection and a valid Certificate of Fitness before operation.
Registered boiler engineers or visiting engineers and boiler operators, according to applicable Twelfth Schedule arrangements.
Appropriately registered competent persons or companies for prescribed specialist work.
Applicable approval for alterations affecting the approved design or operating conditions.
Compliance with applicable statutory and regulatory requirements forms part of ISO 9001 requirements. These legal obligations should therefore be identified and referenced in the Quality Manual and relevant procedures, and fulfilled regardless of certification status.
The management system should connect each regulated item to its approved design, registration details, Certificate of Fitness, competent-person appointments, inspection records and maintenance requirements.
Operating procedures should address the actual hazards, including steam burns, pressure release, vacuum collapse, low-water conditions, scaling, corrosion, chemical cleaning and safe isolation. Protective devices, operating limits and testing arrangements must follow the approved design and applicable requirements.
Water quality and equipment safety require separate evidence: a satisfactory water-test result does not demonstrate that a boiler or evaporator is safe to operate.
8.0 BALANCED DECISION
SWRO carries energy, maintenance and brine-management costs. Intake and discharge arrangements also require environmental assessment. Its suitability should be evaluated alongside demand reduction, leakage control, process-water recycling and other available supplies.
For a coastal industrial development, feasibility should cover the complete system: seawater quality, production demand, power reliability, membrane maintenance, storage, pipelines, environmental requirements and the final water specification.
From a consultancy perspective, this is where process-based management matters: understanding the intended use, identifying risks, establishing controls and retaining evidence that the system consistently delivers what was specified.
The objective is reliable water that is fit for its intended use, supported by sound engineering, safe equipment, controlled operations and evidence of quality.
