10 Litre Resin
Hi-Flow 50 l/min
1–6 People
22mm Install Kit Included
Metered Control
Combi / Unvented / Megaflow
Free BWT Commissioning
The BWT WS455 is the Hi-Flow model in the BWT WS range — a fully automatic metered water softener designed for modern high-pressure plumbing systems including combi boilers, unvented cylinders (Megaflow), and power shower systems. Its 10-litre resin vessel delivers a peak flow rate of 50 litres per minute, ensuring no loss of water pressure even under high simultaneous demand. The WS455 is supplied with a full 22mm installation kit with stainless steel hoses as standard, making it the preferred choice wherever 22mm pipework is present or high flow rates are required.
Like the rest of the WS range, the WS455 uses BWT's metered AMECS control system — regenerating only when the resin is actually exhausted based on measured water usage, not a fixed timer. This results in lower running costs and lower environmental impact. Supplied with a 5-year parts / 2-year labour warranty and free BWT @Home commissioning. Replaces the previous BWT MC450 model.
💡 WS455 Hi-Flow vs WS355 Standard — Which Do I Need?
Choose the WS455 if your plumbing system uses 22mm pipework, you have an unvented (Megaflow/pressurised) hot water system, a power shower, or high simultaneous demand from multiple outlets. Its 50 l/min peak flow prevents pressure drops under load. Choose the WS355 if your system uses 15mm pipework with a conventional combi or gravity-fed set-up and standard flow rates are sufficient.
Key Features
🚿 High Flow — 50 l/min PeakDelivers up to 50 litres per minute peak flow through the 22mm high-flow installation kit, maintaining full water pressure for power showers, multiple simultaneous outlets, and unvented cylinder systems. Continuous service flow of 30 l/min at 1 bar pressure loss.
🔧 22mm Stainless Steel Install KitSupplied with a full 22mm stainless steel hose and valve installation kit as standard — suitable for combi boilers, unvented (pressurised/Megaflow) systems and all modern plumbing configurations. No need to purchase installation kit separately.
💧 Metered Demand RegenerationRegenerates only when required based on actual measured water consumption. Uses 0.3–1.2kg salt per regeneration and less than 75 litres of water per cycle — considerably more efficient than time-clock alternatives. AMECS retains settings for up to 72 hours during power interruption.
🧂 Block & Tablet SaltCompatible with both block salt (up to 8kg) and tablet salt (up to 15kg) — flexible salt sourcing and topping up. Salt level is visible through the transparent door panel without removing the hood.
🔩 BWT Rotary Millennium ValveFitted with the bespoke BWT Millennium Rotary Valve — a low-parts-count, high-reliability valve mechanism designed for long service life. All service and repair must be carried out by BWT engineers to maintain warranty.
🆓 Free @Home CommissioningA BWT-trained commissioning engineer visits after installation to configure the softener to local water hardness, set running parameters, demonstrate operation, and answer customer questions — at no charge. Book directly with BWT after installation.
🏠 Under-Sink Compact DesignAt 532mm high — slightly shorter than the 14L models — the WS455 fits easily under a kitchen sink or in a utility room cupboard despite its high-flow capability. Compact footprint: 270mm wide × 480mm deep.
📋 Replaces BWT MC450The WS455 is the current replacement for the previous BWT MC450 model. If you are replacing an existing MC450, the WS455 is the correct like-for-like upgrade and uses the same 22mm connection configuration.
Technical Specifications
| Specification |
WS455 Detail |
| Resin Volume |
10 litres |
| Dimensions (H × W × D) |
532mm × 270mm × 480mm |
| Household Size |
1–6 people |
| Min Flow Rate (Hi-Flo) |
10 l/min |
| Continuous Flow Rate (Hi-Flo) |
30 l/min |
| Peak Flow Rate (Hi-Flo) |
50 l/min |
| Basic Flow (@ 1 bar pressure loss) |
24 l/min |
| Max Pressure |
5 bar |
| Min Pressure |
1.7 bar |
| Max Water Temperature |
49°C |
| Min Water Temperature |
5°C |
| Inlet / Outlet Connection |
¾" BSP |
| Drain Connection |
½" tube |
| Installation Kit Included |
22mm stainless steel hoses and valves (Hi-Flow) |
| Salt per Regeneration |
0.3–1.2 kg (min/max) |
| Water per Regeneration |
<75 litres |
| Salt Storage |
8kg block / 15kg tablet |
| Max Softened Water Capacity |
1667 litres |
| Electrical Supply |
220V AC / 12V DC |
| Regeneration Type |
Metered demand (AMECS) |
| Memory Backup |
Up to 72 hours |
| Unit Weight (empty / in service) |
18kg / 40kg |
| Warranty |
5 years parts / 2 years on-site labour |
| Replaces |
BWT MC450 |
| Brand |
BWT |
Frequently Asked Questions
Does the WS455 work with an unvented (Megaflow) hot water cylinder?
Yes — the WS455 is specifically designed for high-pressure systems including unvented hot water cylinders (Megaflow, Ariston, etc.) and combi boilers. Its 22mm high-flow connections and 50 l/min peak flow rate ensure the softener does not create a restriction in the mains supply. The WS355 with 15mm connections would be unsuitable for such systems.
Can the WS455 use block salt?
Yes — the WS455 accepts both block salt (up to 8kg capacity) and tablet salt (up to 15kg capacity). The preferred salt type can be set in the unit's programming. Block salt is popular in BWT softeners due to its slow dissolution rate and low dust content compared to granular alternatives.
What is the difference between the WS455 and the WS555?
Both the WS455 and WS555 are hi-flow models with 22mm installation kits and 50 l/min peak flow. The key difference is resin capacity: the WS455 has a 10L resin capacity while the WS555 has 14L. The WS555 therefore regenerates less frequently, uses slightly more salt per cycle (0.6–2.0kg vs 0.3–1.2kg), but holds a larger volume of softened water between regenerations (2500L vs 1667L). The WS555 is suited to larger households or harder water areas where a larger resin volume reduces regeneration frequency.
⚠️ Note: WS455 supplied with 22mm high-flow install kit. An unsoftened drinking water tap is required by Building Regulations Part G. Register within 100 days of purchase for the full BWT @Home warranty and to activate free commissioning. Replaces BWT MC450.
