Majestic 400 RO
A compact, professional-grade reverse osmosis system delivering high flow where space is limited: up to 400 litres per hour from four membranes, housed in hygienic AISI 304 stainless steel for commercial hospitality and foodservice.
About the Majestic 400 RO
The Majestic 400 RO is a compact, professional-grade reverse osmosis system for commercial hospitality and foodservice. A multi-membrane configuration of four 500 GPD membranes delivers up to 400 litres of purified water an hour, from a stainless steel cabinet that fits where space is limited.
The cabinet is hygienic AISI 304 stainless steel, built for durability and easy maintenance in back-of-house installations. Key operating parameters show on the onboard display or in a connected app, and the unit runs quietly enough for front- and back-of-house.
At a glance
- What it is
- A professional-grade commercial reverse osmosis (RO) system
- Purified flow
- Up to 400 litres an hour at 25 °C
- Membranes
- 4 × 500 GPD
- Rejection and recovery
- 92 to 95% rejection, 50% recovery
- Cabinet
- AISI 304 stainless steel, 30.1 kg
- Size
- 220 × 550 × 440 mm (W × D × H)
- Monitoring
- Onboard display and connected app
- Model code
- MAJ 400 · FLO MAJFLT400
What it does.
- Up to 400 L/h of purified water from 4 × 500 GPD membranes
- Hygienic AISI 304 stainless-steel cabinet
- 92 to 95% rejection rate with 50% recovery
- Carbon cartridge pre-filtration (FC500 type) protects the membranes
- Onboard display plus connected-app monitoring
- Quiet operation for front- and back-of-house
Typical applications
Who the Majestic 400 RO is for
- Hotels that need a large, steady supply of purified water from a small footprint.
- Restaurants and commercial kitchens with high-volume demand.
- Foodservice back-of-house where a hygienic stainless cabinet matters.
- Operators who want to monitor key readings on screen or by app.
How the Majestic 400 RO works
The datasheet shows five stages. Potable feed water goes first to a carbon cartridge (FC500 type), which protects the membranes. A rotary vane pump then drives it through the four 500 GPD membranes, and permeate, the purified water, leaves at up to 400 litres an hour.
In general, reverse osmosis pushes water through a very fine membrane that holds back most dissolved salts. This unit is rated at 92 to 95% rejection with a 50% recovery ratio. At 50% recovery, about the same volume of water goes to drain as comes out as purified water.
The 400 litres an hour is quoted at 25 °C, so we check the output against your own feed conditions at survey.
Which one should you choose?
We make several reverse osmosis systems. The right one depends mostly on how much purified water you need and how much room you have.
Imperial RO
You want up to 120 litres an hour from a slim undersink unit with Wi-Fi monitoring and a live display.
Noble RO 60
You have tight space and lower demand, such as a coffee bar or small kitchen, and want 60 litres an hour with an adjustable salinity regulator.
Majestic RO
You need up to 185 litres an hour for busy food and beverage sites, with multi-stage filtration down to 0.1 micron, in a compact unit just 51 cm wide.
Majestic 400 RO
You need the highest flow of the compact units: up to 400 litres an hour from four membranes in an AISI 304 stainless cabinet.
Industrial Reverse Osmosis
You need a plant, not a unit: engineered, skid-mounted reverse osmosis built to your water analysis, up to 56 m3 an hour.
Installation and servicing
The Majestic 400 RO is a stainless cabinet weighing 30.1 kg. It needs a potable feed, power and a drain, which our engineers run at installation. We install it, commission it and, if you want it, look after it on a Comprehensive Maintenance plan.
The datasheet lists a 220 V AC, 50/60 Hz supply at 500 W, a feed pressure of 1 to 6 bar and a feed temperature of 5 to 45 °C. We check these against your site at survey. Reverse osmosis often works best with the right pre-treatment, so we also look at your water hardness.
The survey is chargeable and is credited back if you go ahead.
Majestic 400 RO questions answered
How much water does the Majestic 400 RO make?
Up to 400 litres an hour of purified water at 25 °C, from four 500 GPD membranes.
What are the rejection and recovery figures?
92 to 95% rejection and a 50% recovery ratio.
How big is it?
220 × 550 × 440 mm (width × depth × height) and 30.1 kg.
What is it made of?
The cabinet is AISI 304 stainless steel, chosen for hygiene, durability and easy maintenance.
How do I monitor it?
Key operating parameters show on the onboard display or in a connected app.
What protects the membranes?
A carbon cartridge pre-filter (FC500 type) ahead of the membranes.
Is it noisy?
The datasheet describes quiet operation for front- and back-of-house. It uses a rotary vane pump.
What power and water pressure does it need?
A 220 V AC, 50/60 Hz supply at 500 W, and a feed pressure of 1 to 6 bar at 5 to 45 °C. We confirm the electrical and water details for your site at survey.
What warranty does it have?
The datasheet does not state a warranty period. We confirm the warranty terms at survey.
Do you supply, install and maintain it?
Yes. We supply and install it, and offer a Comprehensive Maintenance plan. The survey is chargeable and is credited back if you go ahead.
Related products
Figures come from the manufacturer datasheet (PDF). Reviewed November 2026.
Supplied, installed and serviced across the UK
Across most of southern and eastern England, mains water is very hard. Rain filtering through chalk and limestone dissolves calcium and magnesium, and that scale coats heating elements, so we size every system to your supply and your equipment.
Tell us about your site and what you need the water for. We specify the system, fit it and keep it running under Comprehensive Maintenance.
Source: Drinking Water Inspectorate, Drinking Water Quality in England triennial report (2020–2022).
Interested in the Majestic 400 RO?
Tell us your setup and we'll specify, supply, install and service the right configuration for your site.
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