Reverse Osmosis Ship — Sizing, Layout & Energy (SWRO Guide)

Reverse osmosis ship systems convert seawater to potable water on board. To size a shipboard SWRO correctly, calculate daily demand (crew + galley/laundry + process uses), add a safety margin, divide by uptime hours/day to get permeate m³/h, and set a conservative recovery (35–45%). A reliable layout is intake → pretreatment → RO → post-treatment → storage with clear controls and interlocks.

Robust interlocks are essential at sea (dosing low-level, sea chest, tank levels, HP pump protections).

Typical recovery 35–45%; colder seawater reduces flux.

Energy ≈ 3–8 kWh/m³ depending on scale, temperature, energy recovery.

Pretreatment quality drives uptime more than the RO itself.

• Typical recovery 35–45%; lower seawater temperature reduces flux.
• Energy often ~3–8 kWh/m³ depending on scale, temperature and energy recovery.
• Pretreatment quality drives uptime more than RO itself.
• Design interlocks matter at sea (dosing low-level, sea chest, tank levels, HP pump protections).

New to RO? See a quick primer on membalikkan osmosis.

Reverse osmosis ship sizing workflow (step-by-step)

A shipboard reverse osmosis (SWRO) system draws seawater from the sea chest, screens and conditions it, then uses a high-pressure pump to force water through RO membranes. Permeate is polished and routed to the fresh-water tank, while brine is discharged overboard per local rules.

Use case fit: commercial vessels, offshore service ships, yachts, island ferries—anywhere bunkering is limited or costly.

Reverse osmosis ship summary & next steps

Ini reverse osmosis ship guide outlined sizing formulas, core layout, energy ranges and a starter BOM. For a fast start, use the free RO sizing calculator and the reverse osmosis ship sizing worksheet, then adapt recovery and pretreatment to your route and seawater temperature.

Sizing workflow (step-by-step)

Inputs to collect

• Crew count dan L/day/person (e.g., 60–120 L)
• Galley & laundry L/day, technical/process L/day
• Safety margin (e.g., +10–20%)
• Uptime hours/day (e.g., 16–24 h available runtime)
• Seawater TDS/temperature, target recovery (%)

Formulas

• Daily demand (L) = crew × L/day/person + galley/laundry + process
• Design demand (L) = daily demand × (1 + safety %)
• Required permeate (m³/h) = design demand ÷ uptime (h) ÷ 1000
• Estimated feed (m³/h) = permeate ÷ (recovery %)

Try the free RO sizing calculator

Downloadable: Ship RO Sizing Worksheet (XLSX)

Array & membranes

• Small/medium skids: 4040 or 8040 elements; arrays like 1:1, 2:1, 2:2.
• Pick HR (high rejection) for product quality or LE (low energy) for lower pressure.

Kiat pro: Design with conservative flux, account for cold seawater, and leave CIP access/ports.

Intake & pretreatment (seawater side)

Intake path

• Sea chest → lift pump → coarse strainer (basket filter)
• Optional multimedia / activated carbon depending on waters
• 5-µm cartridge filter before HP pump (monitor ΔP)
• Chemical dosing as required: antiscalant, SMBS (dechlorination), pH adjust

Why it matters: At sea, the fastest way to lose production is fouling upstream of RO. Stable pretreatment = fewer unplanned stops.

RO skid, pressure & energy

Core hardware

• HP pump (SS316 wetted parts), pressure vessels, Membran RO, instruments (flow, pressure, conductivity), PLC + HMI
• Optional energy recovery on larger SWRO units

Operating envelope

• Pressure commonly tens of bar for SWRO (model-dependent)
• Energy guideline ~3–8 kWh/m³ (smaller units at the higher end; cooler water or high TDS raises demand)

Account for ventilation and access for cartridge changes and CIP cart docking.

Materials & corrosion control

• SS316/316L for piping and pumps; duplex options where needed
• Coatings for frames in marine environments
• Salt-resistant valves, sensors, cables; protect electronics from salt mist

Post-treatment & potable storage

• Remineralization / pH adjustment as needed for taste and stability
• UV or equivalent disinfection
• Route to fresh-water tanks with level interlocks and appropriate venting

Controls & interlocks checklist

• HP pump low-pressure protection (NPSH/sea chest)
• Cartridge ΔP high alarm/shutdown
• Dosing low-level interlock
• Fresh-water tank high/low level interlocks
• Conductivity high divert to drain
• Auto flush on stop/start; CIP enable and permissives

Example spec (editable)

Item	Value (example)
Kapasitas	5 m³/h permeate
Feed	Open-sea seawater, ~35,000 mg/L TDS, 25 °C
Pemulihan	~40% (temperature-dependent)
Array	2:1 with 8040 membranes
Bahan	Frame SS304, wetted SS316L
Controls	PLC + HMI, auto-flush, interlocks as above
Power	As sized per pump curve

Internal links: Industrial RO plants - RO accessories & spare parts - Stainless-steel tanks - Free RO sizing calculator

Bill of Materials (BOM) starter

• Sea chest & lift pump, coarse strainer
• Cartridge filter housing + 5-µm cartridges
• Antiscalant / SMBS dosing packages
• HP pump, RO membranes & vessels, instrumentation
• PLC + HMI + VFD (where applicable)
• UV / remineralization, potable tank connections
• CIP cart/ports, hoses, cleaning chemicals

Maintenance at sea (quick plan)

• Daily: check ΔP, conductivity, flows, chemical levels
• Weekly: change cartridges (or per ΔP), inspect strainers
• CIP triggers: ~10–15% normalized flow loss or ~15% ΔP rise, or product quality drift
• Lay-up: flush, protect membranes per vendor guidance

Pertanyaan Umum

Can ships use RO water directly for drinking?
Yes—after appropriate post-treatment (e.g., remineralization, disinfection) and compliance with your flag/state requirements.

How much energy does shipboard RO consume?
A practical range is ~3–8 kWh/m³, depending on capacity, temperature, recovery, and whether energy recovery is used.

What recovery should I target at sea?
Many designs start around 35–45% and adjust with temperature, fouling risk, and water quality.

When should I run CIP?
Common triggers are 10–15% permeate drop (normalized), ~15% ΔP increase, or sustained quality drift.

What spares should we carry for 3–6 months?
5-µm cartridges, antiscalant and SMBS, pump seal kit, pressure-vessel O-rings, one spare membrane element per train (optional), and critical sensors/UV lamp.