Hard water is notorious for causing unpleasant odours and flavours in drinking water, discolouration and staining on dishware, glasses, and even clothing during washing. Another notable problem with hard water is the buildup of limescale around piping and fixtures and this can be resolved by installing a scale inhibitor. The presence of hard water in households necessitates effective solutions to mitigate these effects so we are going to show you how to install a scale inhibitor.

15mm Scale Inhibitor

What is a Scale Inhibitor?

A scale inhibitor is an inline device installed within water systems to combat the formation of limescale in hard water areas. Typically compact in design, it is added directly to the water supply line, often before appliances or fixtures such as boilers or heaters, that are susceptible to limescale accumulation. This device operates by altering the chemical composition of limescale by incorporating specific chemical agents. These scale inhibitors prevent limescale from attaching to surfaces when water is heated. This mechanism is crucial for protecting household appliances and plumbing systems from the detrimental effects of limescale buildup.

It is important to understand that scale inhibitors do not eliminate the calcium and magnesium ions responsible for hard water. Instead, they focus on mitigating the adverse effects associated with these minerals.

How to Install a Scale Inhibitor?

When it comes to installing a scale inhibitor, having the right tools and materials can make all the difference. Here are the key items you’ll need to unblock an outside drain:

What You Need

  • Pipe cutter
  • Spanner
  • Hacksaw
  • Pipe deburrer
  • Scale inhibitor kit

Step 1 – Select the Installation Site

Choose the installation location for the scale inhibitor, ensuring it’s in the pipeline before the fixture or appliance it will protect. Although most units can be installed either vertically or horizontally, always refer to the manufacturer’s guidelines for specific orientation requirements.

Important! Ensure the installation site is easily accessible for future maintenance, testing, or replacement, which is crucial for the long-term management of the device.

Step 2 – Cutting and Preparing the Pipe

Cut the pipe at the chosen location using a pipe cutter to ensure a clean and square cut. Then, use a pipe deburrer to smooth out any sharp edges, preventing damage to the pipe or the scale inhibitor.

Step 3 – Connecting the Unit

Fit the scale inhibitor into the prepared section of the pipe. If using an electrolytic or magnetic scale inhibitor, position it correctly as per the provided instructions.

Step 4 – Securing the Connections

Tighten all the fittings firmly with a spanner to ensure a stable and leak-proof installation.

Step 5 – Testing the Installation

Turn on the water supply to check for any leaks at the connection points. This step is important to confirm everything is secure and functioning properly.

Step 6 – Final Checks

Review the entire installation to ensure the scale inhibitor is correctly set up and positioned for optimal performance.

Remember, if you’re not confident in performing this installation, it’s advisable to seek the help of a professional plumber. This guide is a general overview and may not cover all specific details for different types of scale inhibitors.

Types of Scale Inhibitors

Scale inhibitors come in various forms, each utilising different mechanisms to combat limescale formation in hard water areas:

Physical Scale Inhibitors

These devices physically alter the properties of water to reduce scale buildup. They often work by changing the crystalline structure of calcium and magnesium minerals, preventing them from sticking to surfaces.

Chemical Scale Inhibitors

Chemical inhibitors use specific compounds to interfere with the scale formation process. They typically introduce substances into the water that bond with calcium and magnesium, reducing their ability to form hardened scale deposits.

Magnetic Scale Inhibitors

These units use magnetic fields to change the electromagnetic properties of mineral ions in the water. This alteration reduces the tendency of these minerals to form scale on the surfaces of pipes and appliances.

Electric Scale Inhibitors

Similar to magnetic inhibitors, electric scale inhibitors use electrical charges to modify the behaviour of minerals in the water. They emit varying electrical frequencies that disrupt the normal formation of scale deposits.

It has been observed that hard water may influence mortality, particularly cardiovascular mortality, and several epidemiological investigations have demonstrated related risks.

Maintenance and Lifespan of Scale Inhibitors

The lifespan of scale inhibitors varies, typically ranging from 5 to 10 years. This duration can depend on various factors such as the type of inhibitor, the hardness of the water, and the frequency of use. Regular maintenance, such as checking connections and monitoring performance, can extend their effective life. Some units may require periodic cleaning or replacement of parts, depending on the manufacturer’s recommendations.

Is a Scale Inhibitor Better than a Water Softener?

Whether a scale inhibitor is better than a water softener depends on your specific needs. Scale inhibitors are designed to prevent limescale buildup without removing the minerals that cause hard water, making them ideal for protecting appliances and plumbing.

Water softeners, on the other hand, physically remove these minerals, providing a comprehensive solution to hard water problems but often at a higher cost and with more maintenance.


Scale inhibitors play a crucial role in managing hard water problems in both domestic and commercial settings. By reducing the formation of limescale, they protect appliances and plumbing systems, thereby improving their efficiency and longevity. Additionally, they contribute to better water quality, preventing issues like staining, discolouration, and unpleasant tastes or odours associated with hard water.

How to Install Scale Inhibitor Infographic
How to Install Scale Inhibitor Infographic

Plumbing Wizard Tips

“Install the scale inhibitor in a spot that’s easy to reach for maintenance or replacement, ideally in the water supply line before the protected fixture, considering both vertical and horizontal options as per the device’s design!”

“Use a pipe cutter for a precise cut and a deburrer to smooth edges, then securely tighten all connections and test for leaks to ensure a stable and efficient setup!”

“Always refer to the manufacturer’s instructions for specific installation details, including the correct orientation and any special requirements for your particular scale inhibitor model!”

Frequently Asked Questions

Where does a scale inhibitor go?

A scale inhibitor should be installed in the water supply line leading to the appliance or fixture you intend to protect from limescale buildup, such as boilers or heaters. It’s typically positioned before these appliances to effectively prevent scale accumulation.

Do you need to replace a scale inhibitor?

Yes, scale inhibitors do need to be replaced over time. Their lifespan varies, typically ranging from 5 to 10 years, depending on the type of inhibitor, water hardness, usage, and adherence to maintenance guidelines.

How long does a scale inhibitor last?

The lifespan of a scale inhibitor generally ranges from 5 to 10 years. This duration can depend on several factors, including the type of scale inhibitor, the hardness of the water in your area, and how frequently the inhibitor is used.

How often do you add scale inhibitors?

The frequency of adding or replacing scale inhibitors depends on the type and model of the inhibitor, as well as the quality of your water. Some models require periodic addition or replacement of chemical agents or parts, as per the manufacturer’s guidelines, while others may have longer-lasting components that don’t require frequent maintenance.


Lee Pearce is not just a master plumber; he’s a veritable Plumbing Wizard. With over 30 years of experience in the trenches of pipes and drains, Lee has become the go-to sage for DIY plumbing, saving homeowners thousands in potential call-out charges. As the founder of Plumbing Wizard, he’s dedicated to demystifying the complexities of home plumbing, offering easy-to-follow advice that stands the test of time and pressure. His online blog is a treasure trove of tips, tricks, and tutorials that empower everyday individuals to take charge of their home’s plumbing health. Lee’s practical wisdom is not just about fixing leaks; it’s about imparting confidence and self-reliance. When he’s not writing or elbow-deep in a plumbing project, Lee is passionate about educating the next generation of DIYers, ensuring that practical skills are passed down and preserved.

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