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Our Expert Opinion
Why Choose the TwinTec S4?
Is it Worth Buying?
Features & Benefits
Recommended Accessories
Warranty
Model Comparison
Price
Running Costs
Installation
Frequently Asked Questions

Our Expert Opinion on This Product

After selling and supporting thousands of water softeners from both Harvey & Kinetico Water Softeners, we've found the TwinTec S4 is the model most customers choose because it balances performance, efficiency and price - offering the same specification as the latest released Harvey models. It's suitable for the majority of UK homes with two to four bathrooms and rarely requires maintenance beyond topping up the block salt.

Why is the Harvey TwinTec S4 one of the best water softeners?

The Harvey Twintec S4 is a twin tank system designed and manufactured by the UK's leading brand - Harvey Water Softener. When deciding on a model - the TwinTec gives the best specification for the best price and is guaranteed to last 10-20 years.

Is the Harvey TwinTec S4 worth buying?

You Should Buy the TwinTec S4 if...

You have a property with 2, 3 or 4 bathrooms or have a family of 2-8 people.
You have limited space underneath your kitchen sink.
You are looking for a softener that will last 10-20 years.
You need to remove hard water & limescale from your home.

Harvey TwinTec S4 Features & Benefits

Click here to view the Harvey S4 Brochure PDF

Harvey TwinTec S4 Specification

Type of System: Twin tank, non-electric, block salt fed system.

Dimensions: 490mm high and 205mm wide with a depth of 440mm.

Efficiency: regeneration water volume of 17L with a time of 11 mins.

Warranty: 10 years parts and 2 years labour.

Max Flow Rate: 56L/min

Max Pressure: 10bar

Salt Usage: 300g per regeneration

Why We Choose The TwinTec Series 4 - Key Features:

Small & Compact Design

Harvey water softener models are generally compact and super easy to fit under the sink. This model in particular will fit neatly underneath most standard UK kitchen sinks, so it is ideal for homes where space is limited. Small and compact, yet efficient and high-performing with high softening capacity.

Twin Tank Design

Single and twin tank are two types of water softener. Unlike a single-cylinder water softener, the Harvey TwinTec S4 uses two resin tanks. This means, while one tank regenerates, the other continues supplying softened water, ensuring your home never runs out of soft water.

Non-Electric Automatic Operation

No electricity required, eliminating the need for plugs, timers or electronic controls. Why is this beneficial? Lower running cost and low maintenance! It automatically measures your water usage and regenerates only when required, helping to reduce running costs while removing the risk of electrical faults or programming issues.

10-Year Parts Warranty & 2-Year Labour Warranty

There’s nothing worse than investing in your home and having an appliance break after 12 months. But the TwinTec Series 4 is designed for long-term reliability and is backed by a comprehensive 10 year warranty. Purchasing through NE Water Softeners means you'll receive dedicated after-sales support, giving you confidence that any issues will be resolved quickly and professionally.

High Flow Rate

Flow rate is important to ensure water pressure can be maintained throughout your home. With a maximum flow rate of up to 56 litres per minute, the Harvey S4 comfortably supplies multiple outlets at once. Whether you're running a power shower, filling a bath or using several taps simultaneously.

Highly Efficient Regeneration

Efficiency is important in order to minimise running costs. Cheap electric or single tank systems tend to have much lower efficiency - meaning they use more water and salt per regeneration. The TwinTec is the most efficient model on the market and is what we recommend for anyone looking to save money in the long run. Each regeneration cycle uses just 300g of block salt and approximately 17 litres of water, completing the process in around 11 minutes.

Patented Metering System

No water wastage here! The patented metering system accurately measures every litre of water used—even down to just a few drips per second. Not only this, but unlike electric softeners, this intelligent technology ensures the system regenerates only when necessary, helping to minimise salt and water consumption while maintaining maximum performance.

Nano Technology Ultra-Fine Resin

This Harvey system also uses a patented ultra-fine resin, so the system softens water more efficiently - squashing running costs to a minimum.

Smart Shuttle Pressure Adaptation

No need to search “best water softener for my boiler type” - whether your home has a combination boiler, gravity-fed system, unvented cylinder or loft tank, the Smart Shuttle metering system automatically adapts to changing water pressures. We find this model the best system for all different plumbing systems.

Proven Reliability

The TwinTec platform has been refined over many years and is trusted by thousands of homeowners throughout the UK. It is actually one of the most reviewed and purchased Harvey Water Softeners! You won’t find a bad review of this model, making it a super safe bet.

Uses Block Salt

The Harvey TwinTec S4 is specifically designed to use block salt rather than tablet or granular salt. Block salt is clean, easy to handle and produces an effective brine solution for regeneration, helping maintain optimum performance while reducing mess during refilling.

Recommended Accessories for Your Harvey Water Softener

When purchasing this system we suggest checking you have the below accessories to make sure you have a seamless set up and easy installation:

Block Salt Packs: You'll need block salt to keep your water softener running and for the removal hard water ions. Each pack comes with 2 blocks of salt. An average use of salt is usually 1 block per person per month.
Installation Kits: It's important to match the correct installation kit to your plumbing. Installation kits typically come in 15mm or 22mm sizes. Including high-quality connectors and fittings, these kits ensure a simple, hassle-free setup. Click here to view in more detail.
Pressure Reducing Valve: In few cases, if the home's water pressure is too high, a pressure reducing valve may be necessary.

How long does the Harvey TwinTec S4 last?

With the TwinTec model you pay for quality - this system lasts anything from 10 - 20 years, and it comes with a 10 year parts warranty to ensure you’re covered.

Harvey TwinTec S4 Warranty

When you purchase your system through us, you benefit from comprehensive warranty coverage: 2 years of labour support (to find out more about our labour warranty get in touch) and a generous 10-year parts warranty.

How does the warranty work?

Here’s how it works:

In the first 6 months, if there is a clear fault with your system we will arrange a pick up of your old unit and send you a brand new one - without a home visit being necessary. In other cases where your water softener develops a fault during the first two years and this fault is harder to diagnose over the phone - we will arrange to diagnose the issue ourselves, and carry out the necessary repairs. There’s no hassle of being referred to an unfamiliar third-party or local tradesperson, ensuring reliable support and a quick resolution.

This applies to systems located across the UK. If you have any issues feel free to ring us at 02031486773 —we’re always happy to help clarify your coverage and point you in the right direction.

Harvey TwinTec Series 4 Water Softener Model Comparison

The Harvey MiniMax Vs TwinTec S4

When Comparing the TwinTec series 4 to other water softeners such as the MiniMax and the Harvey Arc - you'll find the same technical specifications such as flow rate, pressure and efficiency. Find out more in this Harvey Water Softener comparison.

The Harvey TwinTec Series 4 Vs Newest Models

Feature	Harvey TwinTec S4	Harvey Newest Models
Twin-cylinder design	✓	✓
Electricity required	No	No
Salt type	Block salt	Block salt
Maximum flow rate	56 L/min	56 L/min
Regeneration water usage	17 litres	17 litres
Regeneration time	11 minutes	11 minutes
Salt used per regeneration	300 g	300 g
Maximum operating pressure	10 bar	10 bar
Suitable for combi boilers	✓	✓
Suitable for gravity-fed systems	✓	✓
WRAS approved	✓	✓
Manufacturer's parts warranty	10 years	10 years
Typical installation location	Under kitchen sink	Under kitchen sink
Best for	2–4 bathroom homes	2–4 bathroom homes

Harvey Water Softener Price

A Harvey Water Softener price generally depends on the model you are purchasing and the condition of the system.

Our TwinTec S4 systems are on sale for £1174.00. We now also have a buy now pay later option available to help spread the Harvey water softener cost.

Harvey TwinTec S4 Running Costs

This Harvey model is non-electric - meaning it uses no energy or electricity to run 24/7. The machine itself is incredibly low maintenance and all that is required is to replace the block salt needed to soften the incoming hard water! The average block salt usage is one block per person per month.

Salt Usage: How much salt does the Harvey TwinTec S4 use?

The TwinTec S4 is the most efficient model available, using only 300g of salt per regeneration. The average monthly usage of physical salt blocks is 1 block per person per month, more or less depending on how much water your home is using.

Water Usage: How much water does regeneration use?

17L per regeneration cycle - however, it’s worth bearing in mind that this product only regenerates when it needs to. It automatically meters the water and regenerates when the internal resin is saturated - so unlike electric systems, no water is ever wasted.

Electricity Usage: How much Electricity does regeneration use?

None! This system is completely non-electric.

Approximate annual salt cost

We estimate for a family of four around £130 per year for salt. This may fluctuate depending on there being more than 4 people in the home, how hard your water is and your overall water usage.

Harvey TwinTec S4 Installation

For Installation Manual Click Here

Can I install it myself?

A water softener is installed next to the stop tap, which is usually underneath the kitchen sink. This can be easily carried out by a plumber and you will usually require an installation kit. If you have experience with plumbing systems you may be able to carry out the installation, however, we recommend using a qualified plumber to do the job and ensure your warranty is valid with no mistakes made.

Is installation included?

Our online prices exclude installation. We offer installations in select areas in the UK, we also have a list of plumber referrals that can help!

Need help finding an engineer for your installation?

Talk to us today on 02031486773 and may be able to help you.

TwinTec WRAS Approval

This water softener is fully approved by the UK Water Regulations Advisory Scheme WRAS, ensuring it meets the highest UK water safety standards. You can have confidence that it complies with all relevant regulations for installation and operation within your home.

Harvey TwinTec S4 Frequently Asked Questions

Does it actually remove limescale?

Yes! This Harvey water softener not only prevents new limescale but it also gradually removes any existing limescale built up in your pipes.

Does it improve skin?

Hard water causes mineral build up on the skin - resulting in dry skin. For those with sensitive skin it even can cause psoriasis, eczema and worsen acne. Soft water is gentle on skin and can greatly improve skin issues caused by hard water, we find many customers come to us looking for a water softener solely to help their sensitive skin.

Will it help eczema?

Yes! Studies have shown soft water can improve eczema and sensitive skin and living in hard water increases the risk of dermatitis.

Does it improve hair?

Again, due to hard mineral build up, frizzy, greasy and damaged hair with dandruff is one of the biggest hard water complaints. Soft water however, results in silky soft shiny hair and helps prevent dandruff.

Does it protect boilers?

Yes - because water is softened at the incoming source, the boiler is not exposed to hard water or hard mineral build up.

Does it work with combi boilers?

Yes! One of the reasons we love to recommend this system (aside from all the many benefits) is it can be suited for a range of different boilers and systems - including combi boilers.

Can it be installed outside?

It absolutely can be installed outside, however, you must have an outdoor water softener cabinet installed to protect the system from weather and temperature damage.

How often do I add salt?

Usually every month or every couple of weeks. The clear cabinet casing means you can easily see when salt is running low and needs replacing.

What salt does it use?

Standard block salt.

Is block salt expensive?

No! In fact we estimate a salt cost of around £120 per year based on a family of four and average consumption, when salt is purchased in bulk.

Can softened water be drunk?

This is one of the most common questions we get asked and the answer is yes! Soft water is safe to drink except in specific circumstances including: If you are feeding and bottle feeding a small infant, or you follow a medically prescribed extra low sodium diet. In these cases the fix is straightforward - you can isolate your drinking water tap, meaning you can have soft water throughout your home and drinking water from this isolated tap.

Does it reduce water pressure?

No! The high flow rate of the S4 means pressure should be maintained in the home for up to 3-4 bathrooms.

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