Published on 05/14/2020 | by Waterline Admin

As featured in waterline Spring 2020


Scale an introduction – what is scale?

In the water treatment industry scale is a term used to describe a build-up of mineral deposits on the system. The reasons for the formation of the scale can be complex. Scale can contain various chemical compounds sometimes as a mixture. These compounds are commonly formed from the dissolved inorganic impurities found in the water. A common form of scale is the deposit found in kettles in hard water areas.

Some other types of deposits are referred to as fouling which can be caused by microbiological growth or contamination from process (such as oils). If the fouling results in hard deposits it can be referred to as scale. The exact name used to describe the deposit is not important – what is important is to understand what caused the deposit so that action can be taken to remove it and avoid it reappearing.

Calcium carbonate scale (limescale) deposits can be caused by simply warming or evaporation of water containing high hardness and high alkalinity levels. However, there are several factors that can result in deposits, including:

  • • mineral impurities (also called dissolved solids) naturally found in water coming out of solution
  • • corrosion – most commonly rust deposits from the corrosion of iron
  • • incorrect water treatment (e.g. chemicals being incorrectly applied and used, insufficient bleed or blowdown)
  • • overheating, low flow or no flow
  • • contamination of the system water from any source

The appearance of a scale deposit is not a reliable way to find out what it contains. This requires chemical tests often in a specialist laboratory, although some simple site tests can give an idea of some of the components.

Why is this important?

Scale can cause problems in many types of water systems including domestic water, cooling towers, hot and cold closed water systems, steam boilers, cooling towers etc. Examples include:

  • • inefficient heating or cooling, as scale is a poor conductor of heat. This could mean a building is too hot or cold; a ruined product as it was not heated or cooled correctly; damage to equipment due to overheating or even an explosion. It also adds to running costs significantly
  • • blockages of pipe work, heat exchangers, lines to instruments and gauges etc.
  • • damage to valves and other parts of the system
  • • increase in corrosion even with the best treatment chemicals
  • • scale can provide protected conditions and surfaces on which microorganisms might grow. Some of these organisms could cause health problems (e.g. legionella) and also cause serious local corrosion

What can be done to control scale?

In order to minimise any scale in a system you need to understand the type of system, how the system operates, the source of water and its quality. The methods to control scale include:

  • • reduction in the levels of impurities in the incoming water (by pretreatment plant such as base exchange water softener, RO etc.)
  • • addition of acids – great care is needed with this method
  • • addition of chemicals known as scale inhibitors – these must be chosen with care
  • • limiting the concentration of dissolved solids by removing some system water to drain and topping up with fresh or treated water
  • • filtration to remove any deposits before they settle in the system

Usually a combination of methods will be used and expert advice should be sought.

Are there other concerns?

Whatever method of control is selected it is important that its performance is regularly checked. Some methods to control scale can cause other problems such as increased corrosion and some of the chemicals used can be toxic to people or the environment.

Product Spotlight

Single Syringe Test Kit

The world’s fastest Legionella test! Get results on site for the strain of legionella that causes practically all legionnaires’ disease cases and outbreaks in only 25 minutes. On site results removes the risks associated with transportation of samples. Simple to use, no specialist training required. Why would you wait days for test results? Contact us at Wycombe Water a Hydrosense distributor.

Neptune Water Safety

Neptune is an enterprise-grade, web-based water safety monitoring system which uses discrete, wireless multi-probe thermocouple devices that are easily attached to water assets in order to help maintain the safety of an organisation’s water system. By continually monitoring and analysing temperatures and flow events over time, Neptune helps identify conditions likely to create harmful bacteria such as Legionella or cause freeze or scald risk, improving safety for building users.

PrimeLab Photometer

The PrimeLab photometer hand-held Bluetooth® device is expandable and portable, developed for ultimate flexibility for use in a range of water systems. With only one light source and the JENCOLOR multi-spectral sensor used exclusively in the PrimeLab, it is possible to measure all water parameters where the water sample is visibly discoloured after addition of a reagent. Key Features of PrimeLab Photometer: The first and only PrimeLab photometer with just 1 LED / 1 JENCOLOR sensor, covering the 400 wavelength (380nm-780nm). More than a 100 different parameters available. Activation of add-on parameters is possible even after purchase. Powerful PC-software and app with free cloud service. Creating reports and dosage recommendations by just a click, using your individual water treatment chemicals.

Huwa-San TR-50 Silver Stabilised Hydrogen Peroxide

Huwa-San TR-50 is a commercial water disinfectant and biocide designed for shock disinfection or constant dosing. Huwa-San TR-50 kills legionella bacteria and in addition removes biofilm. It is safer to use than chlorine as the disinfection breakdown products are oxygen and water. Independent testing shows that Huwa-San TR-50 provides a very wide spectrum of biocidal activity against bacteria, viruses, spores, fungi, amoebae (such as amoeba acanthus which can act as a host to legionella bacteria) and algae. Use disinfectants safely. Always read the label and product information before use.

MC1+ Protector

Formulated to prevent wear and tear and the resulting debris, MC1+ stops magnetite and other deposits forming. As it does this, it protects the central heating, keeping the boiler working efficiently and helping to ensure the system lasts for longer.

MM2050 - PT100 Thermometer

Four/three/two wire measurement, Max/min functions, Hold function, Dual display, °C/°F/°A selectable, Simultaneous display of real time and max/min/hold measurement, Self calibrating.

MD610 Photometer

The MD610 gives you a mobile device in a modern design with the analytical features of a laboratory photometer. All important water analysis parameters from A(luminium) to Z(inc) are covered. Combined with the high precision of Lovibond® reagents, a reliable and quick analysis of water samples is guaranteed. Reagent tablets, powder reagents, liquid reagents, or cuvette tests are used depending on the method.

Armitage Shanks Markwik 21


(TB H2a) an integral thermostatic bib mixer tap, single long lever mixer. Single flow fixed horizontal nozzle, sequential operation. Sequential operation ensures both hot and cold supply are purged on each use, long lever gives precise control. Insulated technology keeps the ‘hot’ side of the mixer at a safe surface temperature.

AS Shower chrome

AS Shower chrome

Legionnaires‘ disease is usually spread by the breathing in of water vapour containing Legionella bacteria which is then deposited on the lungs. The bacteria thrives in water temperatures between 25 and 45°C and so showers by their very nature create an ideal environment for the bacteria to spread. The AS SHOWER chrome filter provides reliable and immediate protection against Legionella, removing bacteria at the point of use, allowing users to shower safely.