Minimax M3 : Classic performance. Proven reliability.
The Minimax M3 is an extremely efficient and reliable water softener with a 10-year guarantee when fitted by Hydroworks.
The MiniMax M3 fitted neatly under a kitchen sink
The UK’s Most Tried and Tested Water Softener
The MiniMax M3 marked a major leap forward in domestic water softening. When it was released, it set a new benchmark for reliability, performance, and efficiency — and helped Harvey Water Softeners become the Europe’s leading manufacturer.
While the 5th Generation environmentally friendly MiniMax Innova has since taken centre stage, the 4th-generation MiniMax M3 remains a firm favourite.
It’s still available through Hydroworks — either supply only for DIY installation, or fully supplied and installed by our expert team.
Why Choose the MiniMax M3?
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Continuous flow rate: 56 litres per minute
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Peak flow rate: 65 litres per minute
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Ultra-low water usage: Just 17.1 litres per regeneration
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Uses Harvey Original block salt — clean, compact, and convenient
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Ideal for up to 10 people with two bathrooms
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No compromises between flow rate and efficiency
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Includes a 10-year manufacturer-backed parts guarantee
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Compact dimensions: (W)206mm x (H)490mm x (D)445mm
Advanced Features
Smart Shuttle Metering
Breakthrough technology that measures water usage with precision, regenerating only when needed — no waste, no guesswork. Built for all UK plumbing systems, including loft tanks, combi boilers, and high-pressure unvented systems.
Low-Pressure Injector
Even if your home has lower water pressure or pressure fluctuations (e.g. during peak usage), the M3 keeps working at its best — delivering consistent performance without compromise.
High Flow Rates
Unlike older softeners that force you to choose between flow or efficiency, the M3 gives you both. Enjoy fast, uninterrupted water — even with multiple taps running.
Stress Tested Beyond Industry Standards
The M3 has been tested to over 1 million cycles at 15 bar pressure — a huge leap beyond the UK standard. This means decades of reliable service, even in demanding homes.
Internal view showing the twin-cylinder, non-electric system
The salt bay has a red line. If you see the line, you can easily get another block of salt in and still get the lid on.