Water Softener vs Descaler in London: Salt Softener, Salt-Free Conditioner and Magnetic Compared

The Three Technologies Available in London

London has some of the hardest water in the UK at 250 to 400mg/l. Three categories of product are marketed as solutions to London hard water: salt-based ion exchange softeners, salt-free conditioners (also called template-assisted crystallisation or TAC systems), and magnetic conditioners (also called magnetic descalers or electronic descalers). Understanding what each technology actually does — and does not do — is essential to making the right choice for a London property.

Salt-Based Ion Exchange Softener

A salt-based ion exchange softener is the only technology that genuinely removes calcium and magnesium ions from the water supply. The process involves passing water through a resin bed where calcium and magnesium ions are exchanged for sodium ions. The output is chemically soft water — water with very low calcium and magnesium content — that does not form limescale on any surface it contacts.

What it does: Removes calcium and magnesium from the water throughout the property. Prevents limescale on boiler heat exchangers, hot water cylinder elements and coils, taps, shower heads, washing machine elements, dishwasher arms, and all other water-contact surfaces. Improves soap lather. Leaves skin and hair feeling cleaner after washing.

What it requires: Salt tablets for the brine tank, typically one to two 25kg bags per month for a typical London household. An annual service visit to check and sanitise the resin bed. A drain connection for backwash. Space near the rising main — under the kitchen sink, in a utility room, or in a garage.

What it does not do: Softened water has elevated sodium content and is not recommended as the primary source of drinking water, particularly for infants. A dedicated unsoftened drinking water tap is included in every installation by Prestige Engineers.

Cost: Supply and installation from £800 for a compact unit; £1,000 to £2,500 for a whole-house system depending on the unit.

Salt-Free Conditioner (TAC System)

Salt-free conditioners — sold under various trade names and sometimes described as physical water softeners, catalytic conditioners, or TAC (template-assisted crystallisation) systems — do not remove calcium and magnesium from the water. Instead, they claim to modify the crystal structure of calcium carbonate in the water so that it is less likely to adhere to surfaces as limescale. The calcium and magnesium remain in the water; they are carried through the plumbing in a form that is theoretically less likely to deposit as scale.

What the evidence says: Independent testing of salt-free conditioners has produced mixed results. Some studies have found modest reductions in scale deposition in controlled conditions. Others have found no significant difference compared to untreated water, particularly at the high hardness levels typical of London supply. The Water Research Foundation (WRF) and other independent bodies have not found TAC systems to be as effective as ion exchange softeners at preventing scale in high-hardness water.

What it does not do: It does not produce soft water. Soap lather is not improved. Skin and hair feel no different. The measured hardness of the water at the tap is unchanged.

Cost: Typically £200 to £600 installed, depending on flow rate and unit quality.

Magnetic Conditioner

Magnetic conditioners consist of a set of magnets that clip onto or wrap around the pipe and claim to alter the behaviour of calcium carbonate crystals in the water as they pass through the magnetic field. The theory is that the magnetic field causes calcium carbonate to crystallise in an aragonite rather than calcite form that is less adhesive and less likely to deposit as scale.

What the evidence says: The scientific evidence for magnetic water conditioners is very limited. Several independent laboratory studies have found no measurable difference in scale deposition in pipework treated with magnetic conditioners compared to untreated pipework. The claims made for magnetic conditioners by manufacturers are not supported by robust independent evidence, particularly for water with the high calcium content characteristic of London supply.

What it does not do: It does not remove calcium or magnesium. It does not produce soft water. It does not improve lather or reduce sodium. The measured hardness is unchanged.

Cost: £30 to £200 for the device; some are sold online for under £10.

Summary Comparison

• Salt-based ion exchange softener: Genuinely softens water, prevents limescale throughout the property, improves lather, requires salt and annual service — the recommended solution for London hard water
• Salt-free conditioner: Does not remove hardness, may reduce scale adhesion modestly in some conditions, no salt required — a possible supplement in lower-hardness areas but not a substitute for a softener in London
• Magnetic conditioner: No robust evidence of effectiveness at London hardness levels — not recommended as a primary hard water solution

Prestige Engineers installs salt-based ion exchange water softeners across all London boroughs. Contact us for a site assessment and fixed-price supply and installation quote.