Seawater Desalination Equipment: A Practical Guide

Seawater desalination equipment turns salt water into safe, clean drinking water using a process called reverse osmosis (RO). If you are on a cruising yacht, a catamaran, a liveaboard, or heading into remote country, the right desalination unit removes your dependence on shore water, jerry cans, and expensive marina top-ups. This guide explains how the equipment works, what specifications actually matter, and how to match the right system to your situation, whether that is a portable 12V unit you can carry aboard a trailer sailer or a higher-output system for a larger passage-making crew.

How Reverse Osmosis Desalination Works

All modern marine desalination equipment is built around the same core process. A high-pressure pump forces seawater through a semi-permeable RO membrane at around 800 PSI. The membrane rejects dissolved salts, passing only clean water molecules through to the product side. The concentrated brine is discharged overboard. On good seawater desalination equipment, salt rejection rates sit at 99% or better, meaning the output TDS (total dissolved solids) stays well under 500 ppm and typically in the 250 to 300 ppm range, comfortably below Australian drinking water standards.

Before water reaches the membrane, it passes through a pre-filter, usually 5 micron, to strip out sediment and particulates that would otherwise foul and shorten membrane life. After the membrane, many quality units add UV sterilisation as a final barrier against any biological contamination. That combination of pre-filtration, RO membrane, and UV is the gold standard for safe output on any marine desalination system.

The Key Specifications to Compare

When you are shopping for seawater desalination equipment, these are the numbers that actually determine whether a unit will work for your situation:

• Output (LPH): Litres per hour the unit produces at rated conditions. A solo sailor or couple might need 10 to 20 LPH. A family, larger crew, or liveaboard should be looking at 40 to 80 LPH.
• Salt rejection (%): A quality marine membrane rejects 99% or more. Check the output TDS, not just the percentage.
• Power draw: Portable 12V systems typically draw 16 to 18A, which a decent house battery bank and 200 to 400W of solar handles comfortably. Higher-output systems may require 24V or 48V.
• Feed water range: A good RO membrane handles full oceanic seawater up to about 35,000 ppm, plus brackish water and river water.
• Weight and install requirements: Portable units are self-contained and need no installation. Fixed or semi-permanent systems need through-hulls, below-deck space, and wiring.
• Parts availability: Non-proprietary, off-the-shelf components mean you can source replacements anywhere in the world. Proprietary systems can leave you stranded.

Portable vs Fixed Desalination Equipment

This is the biggest decision before you buy. Portable seawater desalination equipment is self-contained: you drop an intake over the side, connect a couple of hoses, and you are making water in minutes. There is no installation, no through-hull, and no yard bill. You can move the unit between boats or take it camping. The trade-off is output, which tops out at around 20 LPH on most portable 12V units, and you run it manually rather than from a panel.

Fixed or modular below-deck systems offer higher output, a remote control panel, autoflush, and the convenience of a button press. They suit larger crews, charter vessels, or anyone who wants water on demand without thinking about it. The trade-off is cost, installation time, and the fact that the unit stays with the boat. For a refit or new build where a permanent install makes sense, a modular kit is the right tool.

If you are unsure which way to go, this existing comparison is worth reading: Portable vs Installed Watermaker.

LEDI's Seawater Desalination Equipment Range

LEDI Watermakers is an Australian company building its systems on the Gold Coast. Every unit uses the same commercial marine-grade components found in fixed watermakers that can cost $10,000 to $25,000 installed, but without the overseas distributor markup or the freight on a large install. Parts are non-proprietary and field-replaceable, which matters when you are 1,000 nm from the nearest chandlery.

LEDI Scout: the portable 12V option

The LEDI Scout is a portable 12V desalination unit available in 10 LPH and 20 LPH outputs. It weighs 18 kg, fits in a single-person carry, and needs no installation. Drop the stainless intake over the side, connect the supplied hoses, and you are making water. The Pumptec 107SS high-pressure pump runs at around 800 PSI and draws 16 to 18A from a 12V supply, so a normal house battery with 200 to 400W of solar runs it comfortably without a generator.

Salt rejection is 99.4%, with typical output of 250 to 300 ppm TDS, well within Australian drinking water standards. A built-in UV steriliser provides a final barrier. The Scout handles everything from full-strength oceanic seawater at 35,000 ppm through to brackish and river water, making it useful well beyond blue-water sailing. It starts from $4,799 AUD and suits trailer sailers, cruising yachts from 20 to 50 feet, catamarans, and campers or 4WD travellers.

LEDI Nomad: higher output for bigger crews

The LEDI Nomad steps up to 40, 60, or 80 LPH output and operates on 12V, 24V, or 48V supply. It includes an integrated control panel, two-stage pre-filtration, TDS and flow monitoring, and autoflush compatibility. At 38 to 42 kg it is heavier than the Scout, and it is aimed at liveaboards, larger crews, charter boats, or anyone making long passages who needs water for showers and heavy daily use. The Nomad is available from $8,299 AUD, with final pricing on the 60 and 80 LPH configurations being confirmed, so contact the team to register your interest.

LEDI Modular: for permanent installs

If you want the equipment out of sight and integrated into the vessel, the LEDI Modular kit is a configurable below-deck system ranging from around 10 to 80+ LPH. It includes a remote control panel and auto freshwater flush. Pricing depends on configuration, so get in touch with the team for a quote tailored to your build.

Maintenance: What Actually Needs Attention

Well-maintained seawater desalination equipment is reliable and long-lived. Here is what routine upkeep looks like in practice:

• Pre-filter: The 5 micron cartridge on the Scout is the main consumable. In clean ocean water, replace it roughly every 30 to 40 hours of run time. In silty or dirty water, that shortens to 10 to 20 hours. A replacement 2.5 x 5" pre-filter cartridge costs $14.50 AUD and takes minutes to swap. If you want to extend the time between changes, the larger 2.5 x 10" cartridge holds more dirt and gives the membrane cleaner feed water. It is included in the Watermaker Install Kit or available separately.
• RO membrane: Not a regular consumable. With proper care, a marine membrane lasts several years. The key steps are a freshwater flush after each use and pickling the membrane if the unit is going into storage. The Seawater RO Membrane is $330 AUD and only needs replacing when output or water quality genuinely falls off.
• Freshwater flush and pickling: Flush with fresh water after every use to clear the membrane of salt. For longer storage, pickle the membrane to prevent biological growth. LEDI's maintenance chemicals cover both steps.
• Spare parts: Every wear part on a LEDI system is field-replaceable. LEDI stocks and ships spares Australia-wide and internationally, usually within one business day. Browse the full range at LEDI Spares.

For a deeper dive into membrane care, see Watermaker Membrane Lifespan: What Shortens It and How to Make Yours Last for Years. For flushing specifics, Watermaker Flushing: How Often, Why It Matters covers the routine in detail.

What Portable Desalination Equipment Actually Costs

Fixed watermaker installs from European brands typically run $10,000 to $25,000 including installation. LEDI's portable equipment starts from $4,799 AUD for the Scout, and there is no installation cost, no yard time, and no through-hull to worry about. Because the parts are non-proprietary commercial marine grade, servicing costs stay reasonable too. LEDI offers a 1-year warranty, extended to 2 years on registration, with lifetime in-house servicing available on the Gold Coast for anything more involved. A full cost breakdown is covered in The True Cost of Owning and Maintaining a LEDI Scout Watermaker.

Choosing the Right Unit for Your Situation

The right seawater desalination equipment depends on three things: how much water you need per day, what power you have available, and whether you want the unit portable or permanently installed.

• Solo sailor or couple, occasional passages, 12V solar setup: The Scout 20 LPH at $4,799 AUD is the practical choice. Portable, no install, runs on a normal house battery.
• Family, larger crew, or liveaboard with daily water demands: The Nomad at 40 to 80 LPH from $8,299 AUD handles heavier use, showers, and longer passages. Register your interest with the team.
• Refit, new build, or you want the system out of sight: The Modular kit is the right call. Contact the team for a configuration and pricing discussion.

If you want to talk through which system fits your setup, LEDI is a real person answering the phone, not a call centre. Reach the team at info@ledi.com.au, call +61 494 562 668, or visit lediwatermaker.com to explore the full range and spares.