How to buy the best water softener

If you're struggling with hard water that stains your appliances or ruins the taste of your drinking water, a water softener could be a savvy investment. But what does it do, and how much do you need to spend? Our expert guide answers your key questions.

A reliable water softener can remove damaging minerals effectively from your water supply. So you'll end up spending less to fix or clean the home appliances you use most often.

Below, we explain how water softeners work, how much they cost and where you can buy them. Plus, we have details on which features to look out for when picking a new model.

What is a water softener?

Water softeners are devices designed to tackle hard water, which has a high mineral content (mainly calcium and magnesium).

Hard water can cause problems in the home, as these minerals can form limescale deposits that build up in pipes and appliances over time. To tackle this, a water softener replaces these minerals with sodium or potassium through a process known as ion exchange.

The system also removes positively charged ions such as iron, which can cause staining.

Do I need a water softener?

You should consider investing in a water softener if you're dealing with the following:

• Your water has an unusual taste, smell or look – it might taste metallic or salty, have an unusual musty odour, or look cloudy due to the undissolved chalk.
• You're noticing more limescale build-up and staining – this can usually be tackled with acidic solutions like white vinegar, which breaks down the calcium in it (see also: How to remove limescale from your kettle).
• You're suffering from dry skin and eczema more frequently – some studies, such as one published in the National Library of Medicine, have concluded that hard water may also contribute to increased skin issues.
• There are water spots left on your glassware and dishes – dishwashers need soft water to clean properly and will occasionally need topping up with rinse aid and dishwasher salt to keep them running smoothly.
• Your pipes are constantly clogged or damaged – hard water can cause mineral deposits to accumulate inside your pipes, leading to clogging, low water pressure, and pipe corrosion if left untreated.

For further information, read our full story on signs you might need a water softener

How much does a water softener cost?

Prices vary depending on the size and type of system – expect to spend around £300 to £1,500. Popular brands include Aqua Cure, BWT, Harvey, Kinetico and Kube.

While the upfront cost can be high, a water softener may help reduce spending on maintenance, cleaning products and appliance repairs over time.

'Don't buy cheap as you'll often have to replace the machine within a handful of years,' says Michael Horsell, senior service/sales technician at Pure Choice Ltd, a Which? Trusted Trader. 'It might also require expensive annual servicing and have a much higher rate of salt usage.'

You’ll also need to factor in ongoing costs. Most systems require salt tablets, which typically cost £20 to £30 for a 25kg bag. 

If you’re mainly concerned about drinking water, a filter jug may be a cheaper alternative. Discover the best water filter jugs according to our tests.

Where to buy a water softener

If you're shopping for a new water softener, make sure you’re handing over your money to a reputable seller. Check the retailer's returns policy and also have a look at customer reviews.

'Speak to a water softener specialist before you buy,' says Michelle Manders, manager at Friendly Water Ltd, a Which? Trusted Trader. 'There is a vast array of models available, and not all of them will be suitable for your home or your plumbing and heating setup.'

Popular retailers that stock water softeners include:

• Amazon – stocks a range of water softeners from big-name brands, including BWT and Kinetico. Expect to spend anywhere between £300 and £600.
• B&Q – prices generally start from around £400, and the retailer also stocks salt tablets.
• Screwfix – sells water softeners made by BWT and Sentinel. Typical prices range from £500 up to £1,000
• Toolstation – stocks water softeners from brands such as Calmag, with prices typically ranging from £500 to £700.
• Wickes – the retailer offers water softeners from Aquadial and BWT, with prices ranging from around £540 to £700

Find out which retailers are rated highly by Which? members with our guide to the best furniture, homeware and DIY shops

Water softener features to look out for

• Size – before you buy a water softener, measure underneath your kitchen sink and then check the machine's dimensions on the manufacturer's website. Terry Cobby, director at Aqua Sensation, a Which? Trusted Trader, says, 'When determining the appropriate size of water softener, you also need to think about water usage, the number of people in your home, flow rates and how often you'll need to add salt.' 
• Salt type – once you've settled on a water softener, check what type of salt the manufacturer recommends. Some machines use salt tablets, while others use larger chunks of block salt. Michael of Pure Choice Ltd adds: 'Never buy cheap salt as it's often impure and leads to a very dirty salt cabinet. Plus, it can create a layer of sludge at the bottom that may then require callouts.'
• Digital display – take some time to familiarise yourself with the machine's built-in display. This usually has a clock, along with information on flow rate and salt level.
• Smartphone app – some water softeners partner with a mobile app where you can access additional information. For example, water softener brand Harvey has its own app called myHarvey, which guides you through the setup process.

Other ways to deal with hard water

Aside from investing in a water softener, there are several other ways to deal with the negative effects of hard water.

To help your appliances last longer, get into the habit of descaling them regularly. See our advice guide on how to remove limescale from your kettle and make sure your dishwasher salt is topped up. You can also use water-softening or anti-limescale products in your washing machine.

Alternatively, you can try fitting a water filter to your taps. These won’t soften water in the same way as a water softener, but they may improve taste and reduce some impurities. A showerhead filter (below) could also be beneficial, as some models are designed to reduce limescale build-up and improve water feel, although results can vary.

These showerhead filters are available to order, but note that we haven't tested them:

How does a water softener work?

Water softeners consist of a mineral tank and a brine tank. They attach to your mains water supply, which means water is softened before it reaches the tap. They’re typically installed at an accessible point in the home, such as under the kitchen sink or in a utility area.

The mineral tank contains resin beads, and this is where the ion exchange takes place. As hard water passes through, calcium and magnesium ions are swapped for sodium or potassium ions, softening the water.

When the system needs to regenerate, a concentrated brine solution is drawn from the brine tank and flushed through the resin to recharge it. The brine tank must be topped up regularly with salt.

Water softeners can be either time-controlled or metered:

• Timed models run on a fixed schedule based on estimated water usage, water hardness and system capacity. They are generally cheaper upfront but can be less efficient.
• Metered models regenerate after a set volume of water has been used, which helps reduce waste and ensures a consistent supply of softened water.

Installing a water softener

When installing a water softener, position it at the point where water enters your home so that all water is softened before it reaches your taps. In many homes, this means installing the unit under the kitchen sink, where it can be connected to the pipework. You might also have access to your water supply at another spot in the house – your garage, for example.

Installing a water softener yourself can prove complicated if you're not experienced with plumbing. 

Use Which? Trusted Traders to find a professional installer near you:

How often should I add salt to my water softener?

To keep your water softener working effectively, you’ll need to top up the salt when levels run low.

According to Michael of Pure Choice Ltd, how often you refill the tank very much depends on the model, water hardness and household usage: 'As a general rule, consider refilling your water softener every two to four weeks.'

Some water softeners have a built-in salt level indicator, which alerts you when it’s time to top up.

Water softener salt tablets are widely available from online retailers and DIY stores, but we haven’t tested specific products.

Problems caused by hard water

If your home has hard water, you might notice an unusual taste or smell, as well as visible signs such as limescale build-up on taps and appliances. Dark stains caused by iron can build up in toilets, and minerals in the water can make it harder to create a lather with soap or shampoo.

Using softened water can help reduce limescale and improve the performance and lifespan of appliances such as showers, washing machines and dishwashers. It may also mean spending less on cleaning products to remove scale and stains.

If limescale has wreaked havoc on your appliances and you're in the market for new ones, check our guide to the best kitchen appliances and the best kettles for hard water.

How hard is my water?

There are several websites you can use to check your local water supply. One such site is Aqua Cure. Simply enter your postcode and it will tell you if you live in a hard-water area.

Hard water is measured in parts per million (ppm) and defined by the Aqua Cure website into these categories:

• Soft water – 0-50ppm
• Moderately hard water – 100-200ppm
• Hard water – 201-275ppm

According to Aqua Cure, hard-water areas are generally found in the south east and parts of Ireland.

Discover the best cleaning sprays, including the best bathroom cleaners for shifting limescale