Overview | Is this right for me? | What it reduces | How it works | Specs | What's included | Installation | Maintenance & costs | FAQs | Reviews

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Overview

The Fountain Arc RO System, based on the Pentair PRF-RO, is a tankless reverse osmosis system designed to produce purified drinking water on demand without an electric booster pump.

Instead, the system uses incoming mains water pressure to drive the RO process, so no electrical supply is required beneath the sink. It requires a minimum incoming pressure of 2.76 bar, making water pressure an important consideration when deciding whether this system is suitable for your home.

Water passes through a carbon pre-filter, twin reverse osmosis membranes and a carbon post-filter. The system can produce up to 70 litres of RO water per hour at 10°C and 60 psi, without storing the treated water in a separate pressure tank.

The Arc is particularly suited to households that want on-demand reverse osmosis filtration but would prefer a pump-free system that doesn't require electricity or a storage tank.

Is this right for me?

Choose this if

• You want reverse osmosis without needing electrical supply under the sink
• You prefer purified water on demand rather than stored in a tank
• You have at least 2.76 bar incoming water pressure
• You want a pump free RO system with a higher output than a conventional low-flow domestic RO system

Not ideal if

• Your incoming water pressure is below 2.76 bar
• Under-sink space is very limited
• You only want to improve chlorine taste and odour. A simpler drinking water filter may be better value

What to check before buying

Check your water pressure first. The Arc relies on incoming mains pressure to drive the reverse osmosis process, so you need at least 2.76 bar available.

You'll also need a cold-water supply, connection to the waste and sufficient under-sink space for the system.

What it reduces and what it doesn't

The Arc combines carbon filtration with reverse osmosis to treat both particulate and dissolved impurities in drinking water.

The carbon pre-filter reduces sediment including sand, silt, dirt and rust particles, as well as chlorine before the water reaches the RO membranes. The reverse osmosis membranes separate dissolved minerals and impurities from the treated water, while the final carbon filter reduces any remaining unwanted taste and odour.

What does reverse osmosis reduce?

Reverse osmosis is particularly useful when you want to reduce total dissolved solids (TDS) and other dissolved substances that conventional sediment and carbon filtration alone cannot effectively reduce. Pentair describes its RO technology as capable of reducing a broad range of dissolved salts, particles, organic molecules and other contaminants.

We don't publish individual percentage reduction claims for the Arc unless they are supported by specific performance data for the PRF-RO system.

What it doesn't do

The Arc is a point-of-use drinking water system, so it won't treat water throughout your home.

Reverse osmosis also reduces naturally occurring dissolved minerals. If you primarily want to improve chlorine taste and odour while retaining the dissolved mineral content of your water, a carbon drinking water filter may be a better choice.

How it works

The Fountain Arc uses four filtration elements across three treatment stages:

1. Carbon pre-filter - reduces sediment and chlorine before the water reaches the RO membranes, helping to protect the membrane stage.
2. Twin reverse osmosis membranes - water pressure forces water through two RO membranes. Purified water continues to the final filtration stage, while the concentrated water containing rejected dissolved substances is sent to drain.
3. Carbon post-filter - gives the RO water a final polish to improve taste and odour before it reaches the drinking water tap.

Unlike a conventional RO system that gradually fills a storage tank, the Arc produces filtered water as you need it. Opening the drinking water tap causes incoming mains pressure to drive water through the filtration process, with no electric pump required.

Specifications

Specification	Fountain Arc RO System
System type	Tankless, pressure driven reverse osmosis
Water production	Up to 70 litres/hour at 10ºC and 60 psi
Minimum incoming pressure	2.76 bar
Filtration	Carbon pre-filter, 2 x RO membranes, carbon post-filter
Storage tank	Not required
Electric pump	Not required
Electrical supply	Not required
Dimensions	515 x 246 x 431 mm
Housing material	Shock-resistant PVC
Drinking water tap	High-flow tap with integrated air gap

What's included

1. Fountain Arc / Pentair PRF-RO system
2. 1 x carbon pre-filter
3. 2 x reverse osmosis membranes
4. 1 x carbon post-filter
5. High-flow drinking water tap with integrated air gap

Installation & placement

The Fountain Arc is designed for installation under the kitchen sink, with a dedicated drinking water tap fitted at the sink or worktop.

The system requires:

• A cold mains water supply
• Incoming water pressure of at least 2.76 bar
• A connection to the waste for the water rejected during the reverse osmosis process
• Space for the 515 x 246 x 431 mm system
• Space to install the supplied drinking water tap

No electrical socket is required because the Arc operates using incoming water pressure rather than an electric booster pump.

Maintenance & running costs

The Fountain Arc uses four replaceable filtration elements:

• 1 x carbon pre-filter
• 2 x PRF-RO membranes
• 1 x carbon post-filter

Filter life will depend on water quality and usage, so replacement intervals should be based on the condition and performance of the system rather than assuming every household will achieve exactly the same lifespan.

Because the Arc operates using mains water pressure, there is no electric booster pump and therefore no electricity consumption from the RO system itself.

As with all reverse osmosis systems, some incoming water is discharged to waste as part of the membrane separation process.

FAQs

Does the Fountain Arc RO system need electricity?

No. The Arc uses incoming mains water pressure to drive the reverse osmosis process, so it doesn't require an electrical supply or electric booster pump. Your incoming water pressure needs to be at least 2.76 bar.

Does it need a storage tank?

No. The Arc is a tankless, on-demand system. It produces RO water when the drinking tap is opened rather than producing it slowly and storing it in a separate tank.

How much RO water can it produce?

The Arc can produce up to 70 litres per hour at 10ºC and 60 psi. Actual output can vary with incoming water pressure and temperature.

What filters does the Fountain Arc use?

It uses a carbon pre-filter, two reverse osmosis membranes and a carbon post-filter. Replacement filters and membranes are available separately.

How is the Arc different from a conventional reverse osmosis system?

Many conventional domestic RO systems use a storage tank because purified water is produced relatively slowly. The Arc is designed to provide a continuous, on-demand supply without a storage tank, while also operating without an electric booster pump.

Reviews

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