Is a water softener worth it in a London home?
For most London homes a water softener is worth it if limescale is costing you time and money: furred-up showers and taps, kettles that need descaling every few weeks, or a hot water cylinder or combi boiler that keeps losing performance. London's water is mostly hard, and a salt-based softener is the only household option that actually removes the hardness rather than slowing the scale down. It is less worth it in a small flat with one bathroom, no space under the sink and no stored hot water, where a scale reducer on the boiler feed and regular descaling may do enough. The trade-offs are the space, a drain connection, salt refills and keeping one unsoftened tap for drinking.
Loyal Plumbers · Updated
Discuss your plumbing workWhat a water softener actually does
Hard water carries dissolved calcium and magnesium. When it is heated, those minerals come out of solution and form limescale on heating elements, heat exchangers, shower heads and glass. A conventional softener passes the incoming water through a bed of resin that swaps the calcium and magnesium for sodium. The water that comes out is soft, so new scale stops forming.
Every so often the resin is full and needs recharging. The softener flushes it with brine made from the salt you add, and sends that rinse water to a drain. Most units decide when to do this by metering the water you use, which is why they usually need a small electrical supply. Some twin-tank designs work without electricity.
A softener does not filter the water or improve its safety. Mains water in London is already treated to drinking standard. If your concern is taste, chlorine or sediment, that is a filter question, not a softener one.
Where the benefit shows up
The payoff is mostly in the hot water side of the house, because heat is what turns hardness into scale.
An unvented cylinder or Megaflo keeps its coil and immersion element clean. A combi's plate heat exchanger, which heats the tap water, is one of the parts most often damaged by scale in hard water areas, and a scaled plate heat exchanger shows up as hot water that fluctuates, runs lukewarm or takes longer to arrive. Electric showers, dishwashers, washing machines and coffee machines last longer and need less descaling. Around the house you use less soap and detergent, and glass shower screens and chrome stay clean for longer.
- Hot water cylinders: less scale on the coil and immersion heater
- Combi boilers: protects the plate heat exchanger that heats tap water
- Showers and taps: fewer blocked spray heads and stiff cartridges
- Appliances: less frequent descaling and fewer element failures
- Cleaning: less limescale on screens, tiles and sanitaryware
The downsides and running costs
A softener is not fit-and-forget. Budget for the running costs as well as the unit and installation, and be honest about whether you will keep the salt topped up.
| Item | What to expect |
|---|---|
| Salt | Block or tablet salt topped up regularly; how often depends on the unit, your water hardness and how much you use |
| Water and electricity | Some water is used to regenerate the resin; metered units use a small amount of power |
| Space | Usually under the kitchen sink or near where the main supply enters; it needs to stay reachable |
| Connections | A bypass valve, backflow protection and a drain for regeneration water |
| Servicing | Periodic checks and cleaning in line with the manufacturer's instructions |
| Drinking water | One tap, normally the kitchen cold, left unsoftened for drinking and cooking |
Drinking water, baby feeds and the heating system
Softened water contains more sodium than the water that went in. The usual advice is to keep at least one unsoftened cold tap, normally at the kitchen sink, for drinking and cooking, and not to use softened water for making up baby formula. Planning that drinking-water route is part of the installation, not an afterthought.
The heating circuit is a separate question. Some boiler manufacturers do not want a sealed central heating system filled or topped up with softened water, or only allow it with a compatible inhibitor. Your installer should check the boiler instructions and, where needed, keep the heating fill point on an unsoftened supply.
If you already have a softener and plan a new boiler or cylinder, tell the installer at the survey. It can change where the filling loop is connected and which inhibitor is used.
Softener or scale reducer?
Scale reducers are the cheaper alternative. Polyphosphate dosers, electrolytic and magnetic devices sit on the pipe and aim to stop scale sticking to surfaces, but they do not remove the hardness, and results vary between products and homes. In hard water areas, the Domestic Building Services Compliance Guide expects some form of scale protection on the cold feed to a combi boiler or water heater, and a scale reducer is the usual way that requirement is met.
A softener goes further: it treats the whole supply it serves, so you get the cleaning, appliance and shower benefits as well as protecting the boiler or cylinder. It also costs more to buy, install and run.
- Small flat, combi boiler, one bathroom: a scale reducer on the boiler feed is often enough
- House with a cylinder or Megaflo: a softener protects the biggest investment in the hot water system
- Several bathrooms, glass screens, heavy scale on taps: a softener usually pays off in time saved
- No drain or no space near the supply: a softener may not be practical without other work
What installation involves
A softener goes on the incoming cold main, after the stopcock and before the branches it is meant to treat. The installer fits a bypass so the house can be supplied if the softener is taken out of service, suitable backflow protection, and a waste connection for the regeneration water. The drinking tap branch is taken off before the softener. Most kitchens can take a unit in the sink cupboard, but older London houses often have the main entering under a floor or in a cellar, which can make the route longer.
A softener that discharges regeneration water to drain is often notifiable to the water supplier before it is installed, under the water fittings regulations. A competent installer will know whether your installation needs notifying and will handle it. Our guide to keeping the drinking-water route clear covers how treated and untreated outlets should be separated.
How to tell if your water is hard enough to bother
Your water supplier publishes the hardness for your postcode; in most of London it is hard or very hard. You will also see the signs: white crust on tap aerators and shower heads, scum on the bath, and a kettle that needs descaling often. If your cylinder or combi has needed descaling or a new heat exchanger, or an immersion element has failed early, hard water is the likely reason.
A simple hardness test strip gives you a figure to compare before and after, and many softener manufacturers supply one.
Get a softener fitted or plumbed in
Loyal Plumbers installs and plumbs in water softeners across London and everywhere inside the M25, including the bypass, drain, backflow protection and a separate drinking-water tap. We can fit a unit you have already chosen, or look at your supply, hot water system and space and tell you whether a softener or a scale reducer makes more sense.
Call us or send an enquiry with the type of boiler or cylinder you have, where the stopcock is and where you would like the unit to go.
Common questions
- Is softened water safe to drink?
- It is safe for most adults, but it contains more sodium. The usual advice is to keep an unsoftened cold tap for drinking and cooking, and not to use softened water for baby formula.
- Will a water softener remove existing limescale?
- Over time soft water can gradually loosen some existing scale, but do not rely on it to clear a badly scaled cylinder or heat exchanger. Those may still need descaling or replacing.
- Does a water softener lower water pressure?
- A correctly sized softener should cause only a small pressure drop. If pressure falls noticeably, the unit may be undersized for your flow or the resin or pre-filter may need attention.
- Do I need a softener if I have a combi boiler?
- Not necessarily. A combi in a hard water area should have scale protection on its cold feed, which is usually a scale reducer. A softener adds protection for showers, taps and appliances as well.
- Where does a water softener go?
- On the incoming cold main after the stopcock, usually in the kitchen sink cupboard, a utility room or a garage, with access to a drain and normally a socket.
Sources and further reading
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