RARE Plumbing is now an authorised installation partner for BWT OnePipe Pearlwater — the world's first water treatment system to deliver softened water throughout your entire home and premium mineralised drinking water, all from a single pipe.
Why London Homes Need Water Treatment
London has some of the hardest tap water in the UK. Water travelling through chalk and limestone geology picks up calcium and magnesium carbonates at concentrations of 290–350mg/l — classified as "very hard" by Thames Water. This is a material challenge for any London home with a boiler, unvented cylinder, or high-end appliances.
Limescale deposits coat heat exchanger surfaces inside boilers, reducing efficiency and eventually causing failure. They clog shower heads, shorten washing machine and dishwasher lifespans, and leave white residue on taps, tiles and glassware. For London's prime residential properties, hard water is one of the most common — and most preventable — causes of heating system damage we encounter.
Read our full guide: Hard Water in London: What It Does to Your Heating System.
What is BWT OnePipe Pearlwater?
BWT (Best Water Technology) is Europe's largest water technology company, trusted by millions of households across 70 countries. The OnePipe Pearlwater system represents a genuine breakthrough: for the first time, a single-pipeline solution delivers two distinct water qualities throughout a home.
Softened Pearlwater flows from every tap, shower and appliance — 0.0 ppm hardness, protecting your entire plumbing infrastructure from limescale. Around 98% of household water is used for washing, bathing and cleaning; softened water across all of this makes the greatest difference to your appliances, skin, and laundry.
Mineralised drinking water is available at the touch of a button from your kitchen tap. The Pearlwater Mineralizer, installed discreetly under almost any sink, transforms softened water into fresh, smooth drinking water enriched with magnesium, zinc and silicates — removing chlorine, heavy metals and sediment in the process. No bottles. No bulky filters. No added clutter.
The Benefits at a Glance
Protect your boiler & appliances
Stop limescale at source. Softened water throughout your home prevents scale in your boiler heat exchanger, cylinder, washing machine and dishwasher.
Improve heating efficiency
Limescale acts as an insulating layer inside heat exchangers. Removing it can reduce boiler energy consumption by 12–15% and extend system lifespan significantly.
Mineralised drinking water on demand
The Pearlwater Mineralizer delivers fresh, magnesium- and zinc-enriched drinking water straight from your kitchen tap — no bottles, no filters to change constantly.
Reduce plastic waste
Replace bottled water entirely. The OnePipe system eliminates the need for single-use PET bottles, aligning with the sustainability values of London's most considered homes.
Single-pipe simplicity
Unlike traditional systems that require separate pipework for softened and drinking water, OnePipe delivers both from one pipeline — cleaner installation, less disruption.
BWT Best Water App
Monitor your system remotely. Track water consumption, receive salt level reminders and check system status from your smartphone, anywhere.
How OnePipe Differs from a Traditional Water Softener
Traditional whole-house softeners soften all water, including drinking water — which some households prefer to keep unsoftened due to taste or sodium content. This historically meant running a separate cold water drinking supply ("potable bypass"), adding pipework complexity and cost.
BWT OnePipe eliminates this compromise. The single-pipeline approach means one clean installation, less disruption during fitting, and no dedicated drinking water pipe. The Mineralizer then adds back the beneficial minerals removed during softening, creating drinking water that is genuinely superior in taste to standard London tap water.
For London's prime residential market — townhouses in Marylebone and Mayfair, mansion flats in Knightsbridge, period homes in Hampstead — this level of engineering elegance is exactly what discerning clients expect.
The BWT Best Water App
The OnePipe system integrates with the BWT Best Water App, giving you complete visibility and control of your home's water treatment from your smartphone. Key features include:
- Salt level reminders — receive a notification when your softener needs replenishing
- Real-time status — monitor water consumption, device settings and system health
- Service tracking — monitor upcoming service intervals and maintenance history
- Remote control — adjust settings without accessing the unit
This kind of connected intelligence fits naturally into the smart home ecosystems we install across prime London properties, alongside Heatmiser smart heating controls and connected boiler monitoring.
See OnePipe Pearlwater in Action
RARE Plumbing: London's Authorised BWT Installation Partner
As an authorised BWT installer, RARE Plumbing handles every stage of the OnePipe Pearlwater journey:
- Property survey — we assess your mains water entry point, available space, and water usage to specify the correct unit size
- Installation — our Gas Safe engineers install and commission the system to BWT's exacting standards
- Mineralizer fitting — we install the under-sink drinking water kit to your kitchen tap, including any tap upgrade required
- App setup — we connect your system to the BWT Best Water App and ensure you're comfortable with its operation
- Ongoing servicing — annual servicing, salt supply advice and remote monitoring support
We serve clients across Mayfair, Belgravia, Knightsbridge, Marylebone, Hampstead, St John's Wood, Notting Hill, Primrose Hill, South Kensington and throughout prime central and north London.
Interested in BWT OnePipe Pearlwater?
Contact our team for a property survey and recommendation tailored to your London home.
Frequently Asked Questions
What is the BWT OnePipe Pearlwater system?
BWT OnePipe Pearlwater is an innovative water treatment system that delivers two things from a single pipeline: beautifully softened water to every tap and appliance throughout your home, plus naturally mineralised drinking water at the touch of a button from your kitchen tap. It's the first system of its kind to combine full-home softening with premium drinking water remineralisation in one elegant installation.
Why has RARE Plumbing partnered with BWT?
RARE Plumbing has partnered with BWT — Europe's largest water technology company — because protecting London homes from hard water damage is central to what we do. London's exceptionally hard water (290–350mg/l) causes significant damage to boilers, cylinders and pipework. BWT OnePipe Pearlwater is the most advanced solution we've found, and we're proud to offer installation, commissioning and aftercare to our clients across prime central London.
How does a water softener protect my boiler?
Limescale from London's hard water builds up inside boiler heat exchangers, reducing efficiency and ultimately causing costly failure. Manufacturers including Vaillant, Viessmann and ATAG specify maximum water hardness and may void warranties in hard water areas without treatment. A BWT water softener removes calcium and magnesium ions before they can form scale, protecting your investment and maintaining manufacturer warranties.
Is OnePipe Pearlwater suitable for London flats and houses?
Yes. The system is designed for modern and traditional properties of all sizes. For houses, the system is installed where the mains supply enters the property. For flats and apartments, BWT and RARE's engineers can advise on the best configuration for your specific layout and water usage.
Can RARE install and service the BWT OnePipe system?
Yes. As an authorised BWT installation partner, RARE's engineers are trained to install, commission and service the full OnePipe Pearlwater system. We handle everything from surveying your property and specifying the correct unit, through to installation, salt supply advice and annual servicing.