Offgrid FinalStage RO compact reverse-osmosis drinking-water unit
Offgrid FinalStage RO system and supplied components
FinalStage RO under-sink installation diagram
Reverse-osmosis membrane for the Offgrid FinalStage RO unit
Offgrid Water

FinalStage RO

Adds a separate, low-volume tap for drinking and cooking to a suitably pre-filtered water supply.

Includes: RO unit, two cartridges, drinking-water tap, and 12V and mains power options.

Sale price£490.00

Lead time: typically 1–2 weeks due to batch production and configuration.
Benefits for your setup

At home, on board or in a cabin, using a suitable existing supply.

  • Fewer bottles to buy, carry and store, with drinking water from your own RO tap.
  • Make tea, cook dinner and fill your bottle from one dedicated drinking-water tap.
  • Keep more space for living, with a compact unit tucked out of the way.

Remineralised water for drinking and cooking from a dedicated tap. This compact reverse osmosis unit works after suitable pre-filtration, including Offgrid StageOne or StageTwo, and can also treat standard domestic mains water.

  • Includes: reverse osmosis unit, two long-life cartridge filters and dedicated drinking-water tap.
  • Flow: 1.6 L/min.
  • Power: both 12V DC and 230V mains options included.
  • Installation: indoor use; tap requires a 23mm hole.

Use the RO tap for drinking and cooking: filling the kettle, cooking pasta or rice, making soup and preparing food.

Boiling is not enough. It kills germs but does not remove heavy metals or nitrates. Reverse osmosis can reduce these and other dissolved contaminants that boiling leaves behind. The reduction achieved depends on the contaminant, membrane, water conditions and maintenance.

Lead time: typically 1–2 weeks due to batch production and configuration.

A pre-filter is required before RO operation.

Warranty: 2 years for the system; 1 year for pumps. If something goes wrong, get in touch. We supply covered replacement parts and help you fit them. Callouts aren't included.

How it works & installation

Reverse osmosis can reduce dissolved contaminants, including nitrates, fluoride and metals such as lead. Performance depends on the contaminant, membrane and water conditions. An alkaline post-filter then remineralises the water, restoring beneficial minerals and giving it a clean, fresh taste.

Use after StageOne V3.1 or StageTwo Water Filter, or with domestic mains water. Suitable for boats, off-grid homes, workshops, cabins, RVs, utility rooms and domestic kitchens.

Install indoors and provide a 23mm hole for the included drinking-water tap. Suitable pre-filtration is required before the RO unit.

Specifications
Source water purified Water purified by StageOne + StageTwo, stagnant tank water, or mains
Power use 75W (1.4W standby); both 12V DC and 230V mains power options included
Dimensions W14cm × D45cm × H40cm
Weight 10kg
Weatherproofing Indoor use only
Flow rate 1.6 litres per minute
Filters 2 × long-life cartridge filters
Warranty 2 years for the system; 1 year for pumps
Filters & running costs
PCT pre/post carbon filter replace every 9–12 months
Reverse-osmosis membrane replace every 1–3 years, depending on use and source water
Running costs £70–£90 per year

The FinalStage RO Filter Set includes the PCT pre/post carbon filter and reverse-osmosis membrane.

Treatment & documentation

NSF/ANSI certified components

The FinalStage RO uses drinking-water treatment components from manufacturers with products certified to NSF/ANSI 42 and 58. Certification applies to the relevant listed components, not the complete Offgrid Water system.

Warranty & support

Warranty: 2 years for the system; 1 year for pumps.

If something breaks, let us know. We'll help identify the issue, send you a replacement part where needed and get it resolved as quickly as possible.

At Offgrid Water, we want every customer to have a working system. Happy customers are the best recommendation we can hope for.

Inside the system

Get to know your setup.

Hover over a numbered point or select a feature. On a phone, tap to explore.

Offgrid FinalStage RO compact reverse-osmosis drinking-water unit

Hover, tap or use the feature buttons. Where labelled, concealed components are marked on their casing; they are not exposed in this view.

Drinking water

A dedicated drinking-water supply.

1.6 L/min

FinalStage RO supplies remineralised drinking water from its own tap.

Feed it with suitably pre-filtered water. Do not connect directly to untreated canal or river water.

Inside

Filtration inside a compact enclosure.

RO + pre/post carbon

The system includes two long-life cartridge filters and a dedicated drinking-water tap.

The individual cartridges are concealed by the outer casing.

Power

Two supply options included.

12V DC / 230V mains

Choose the included power option that suits your installation. Listed consumption is 75W, with 1.4W standby.

Check the supplied power equipment and installation instructions.

Fit

Plan the unit and the tap together.

14 × 45 × 40cm

The unit is for indoor installation. The included drinking-water tap needs a 23mm hole.

Allow access for connections and filter replacement.

Filters

Two different replacement intervals.

PCT: 9–12 months

Replace the RO membrane every 1–3 years, depending on source water and use.

The replacement set contains the PCT pre/post carbon filter and the RO membrane.
  • 5 stars: 5 (100%)
  • 4 stars: 0 (0%)
  • 3 stars: 0 (0%)
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  • 1 star: 0 (0%)
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simon creed
Works great

14 years of moving mainly becuase we ran out of water, Now i can get 14 days at any location as i am not hunting down taps, which are becoming rarer each day. Its a great system. the water coming out of the RO tastes great and contains no Flouride or chlorine. Damian is great answers my emails at all hours. So far i am impressed. Requires some basic Plumbing knowledge as its a self install. BUt really is a game Changer

O
Oliver Arnold

We’ve been installing reverse osmosis water filters from Offgrid Water into our campervan conversions for over two years now, and we couldn’t be happier with the product.

Our clients constantly give great feedback. Having access to clean, great tasting water while living the off-grid dream makes a huge difference to their experience. As most campervans rely on onboard or underslung water tanks, water can sometimes taste stale and, if tanks aren’t properly maintained, there’s always the potential for bacteria to build up. The final stage RO unit is absolutely perfect for this application, giving our customers real peace of mind about their drinking water quality.

The system fits neatly into our kitchen units, integrated seamlessly into our builds, and has become a really popular upgrade option for our clients. Importantly, we’ve had no issues down the line - the reliability has been excellent.

We’ll definitely continue installing Offgrid Water systems in our vans and would highly recommend them to anyone looking for a high-quality water filtration system.

Oli thank you for your review, it's always a pleasure to supply your customers with Offgrid Water units!

D
Doug
The only downside is I can't touch tap water now!

These units are fantastic and we use the full system on our narrowboat on the Kennet and Avon Canal. The water filter has been a game changer and we have now been drinking the water daily for a year and I feel great! It looks good, tastes good and all the tests I put it through tell me everything I need to know. Thanks team

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Ricky Bailey
Game changer!

Having this water purifier in our camper has been a complete game changer. No more big plastic bottles of water and no more worry about whether the water is safe to drink! It's super compact, easy to use and customer support is excellent as well! Thanks so much for this brilliant solution.

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Piers
Tastes good

After having this installed, I compared the taste of mains water filtered through it from my water tank (mild steel + tank blacking) vs mains water from a potable water gerry can filtered through a Brita filter. Previously I drank the latter (and never drank from the tank). The water that came through the RO unit tasted significantly better. It looks fine and works well, so far (it's been in a few months). I got someone in to install it as the outlet for waste water from the RO unit wasn't entirely straightforward in my boat (this will depend on each boat's individual setup, it might be easy on some boats). Everything else was just push-fit and very easy. Damian was helpful throughout. I'm very happy with it.

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