Watermaker, Freshwater Generator or Desalination Plant? A Buyer's Guide to the Terminology

If you search for equipment that turns seawater into drinking water, you will meet three different words for essentially the same machine: watermaker, freshwater generator and desalination plant (or SWRO system). They are not synonyms for three products — they are three markets, each with its own habits, units and buyer expectations. Knowing the difference saves a lot of time on both sides of an enquiry.

1. Watermaker — the boating and yachting term

Watermaker is the standard word in sailing, motoryacht and small-vessel circles. A watermaker is a compact reverse osmosis unit installed on board: it draws seawater through a sea strainer, pushes it through membrane elements at 55–70 bar, and sends the permeate to the potable tank after UV sterilisation and usually remineralisation.

• Typical capacity: 30 L/h up to about 3,300 L/h on large yachts (roughly 0.7–80 m³/day, 200–20,000 GPD)
• Power: 12/24 V DC on sailing yachts, or 220–480 V AC on motoryachts; energy consumption around 3–5 kWh per m³ with modern energy recovery
• What the buyer cares about: noise, footprint, litres per hour per amp drawn, ease of pickling when laid up, and service availability in cruising grounds
• Search phrases used: watermakers for boats, water maker for sailboat, marine watermaker for sale, boat water maker prices, DIY watermaker for boat

On yachts above roughly 40 m and on commercial vessels the same machine is more likely to be discussed with the engine room than with the captain — which is where the next term comes in.

2. Freshwater generator — the shipping term

Freshwater generator, often shortened to FW generator or simply FW unit, is what marine engineers, shipyards and purchasing departments say. It is the English equivalent of the Chinese word 造水机 (literally "water maker machine"). Historically many FW generators were evaporators — vacuum distillation running on engine jacket-cooling water heat — and that type is still common on large merchant vessels. Modern equivalents use reverse osmosis, which needs far less energy and no steam supply.

• Typical capacity: 5–100 m³/day (1,300–26,000 GPD) depending on complement and machinery demands
• Power: three-phase 380 V/50 Hz or 440 V/60 Hz; class approvals are usually required
• What the buyer cares about: reliability under continuous duty, materials against seawater corrosion (316L, duplex stainless), class certification (CCS, BV, ABS, DNV), and spares availability in commercial ports
• Search phrases used: freshwater generator for ships, marine FW generator, ship freshwater generator manufacturer

So if an enquiry from a Korean or Turkish shipyard asks for a "freshwater generator", they want the same thing as a yacht owner asking for a "watermaker" — just bigger, harder-wearing, and documented for survey.

3. Desalination plant / SWRO system — the industrial term

Once the move is made to land, islands, resorts or industrial supply, the language changes again. Engineers and procurement teams say seawater desalination system, SWRO plant (seawater reverse osmosis) or simply desalination plant. These are projects rather than products: they involve intake design, pretreatment trains, energy recovery, brine discharge permits and civil works.

• Typical capacity: from 10 m³/day for a village up to tens of thousands of m³/day for municipal supply, arranged as modular trains
• Power and economy: around 3–4 kWh per m³ with pressure-exchanger energy recovery; all-in water cost of roughly USD 0.55–1.00 per m³ depending on plant size and power tariff
• What the buyer cares about: life-cycle cost, membrane life under local feed conditions, containerisation for shipping, remote monitoring, and operator training
• Search phrases used: seawater desalination system, seawater desalination equipment manufacturers, SWRO plant cost, sea water desalination plant cost, containerized desalination plant

4. The three terms side by side

5. What to put in an enquiry

Terminology gets you to the right supplier; the specification below gets you an accurate quotation first time:

1. Feed water: open ocean seawater, brackish water or municipal supply, with TDS if known
2. Daily demand: m³/day (or GPD), plus the peak draw in any single hour
3. Power available: voltage, phase and frequency, and whether generator capacity allows the starting current
4. Product water standard: drinking water (WHO / GB 5749), boiler make-up, or process water
5. Space and environment: available footprint, ambient and seawater temperature range, salt spray exposure
6. Certification: class society approval, CE, or local authority requirements
7. Spare parts plan: filters and membranes for 6–12 months, especially for remote locations

6. Why we publish this

As a manufacturer we quote all three categories, and most specification problems start with a vocabulary mismatch rather than with the equipment. Understanding the three terms helps you read our quotation correctly — and helps us quote to your actual duty rather than to an assumed one.

Shenzhen Duruofei Technology Co., Ltd. builds the whole span: compact marine watermakers from 1.5 m³/day, shipboard freshwater generators (RO type) up to 100 m³/day, and containerised SWRO plants up to 240 m³/day and beyond. Tell us which of the three you need, or simply send the seven points above, and we will return a configuration, a power budget and a water cost estimate within 24 hours.