Water softener for the home - how it works and how the Aquarea team chooses a model
Limescale in a kettle is visible to the naked eye. At home, however, it also accumulates where cleaning is far more difficult - in the heat exchanger of a heating boiler, on the heating element of a boiler, and inside plumbing pipes. A water softener reduces the formation of new scale in these components. The Aquarea team will select a system for your home based on water hardness, consumption, and the layout of your pipes.
What is water hardness and why does it vary from place to place?
Water hardness is primarily determined by the calcium and magnesium dissolved in it. As water passes through soil and rocks, some of the minerals dissolve into it. This is why even water from two different wells can have different levels of hardness. You need more soap to create a lather in hard water, and when water is heated, limescale can form on heating surfaces. USGS - The Science of Water Hardness.
What does this mean for drinking water? The World Health Organization (WHO) does not set a health-based guideline for the hardness of drinking water. The practical reason for softening water at home is usually to reduce limescale and maintain appliances. Other chemical and microbiological indicators are also assessed to evaluate the potability of water. WHO official definition of water hardness (PDF).
What does "total hardness" mean in a water analysis?
In Georgia, the unit used to denote total hardness in water analysis is milligram-equivalents per liter (mEq/L). Below is the Alekin scale for the hardness of natural waters, which is described in the Georgian textbook "General Hydrology." These categories describe water hardness. Evaluating drinking water quality and protecting appliances requires its own specific criteria. "General Hydrology" - Classification of natural water hardness (PDF).
| Total hardness, mEq/L | Alekin scale |
|---|---|
| 0–1.5 | Very soft |
| Over 1.5, up to 3 | Soft |
| Over 3, up to 6 | Moderately hard |
| Over 6, up to 9 | Hard |
| Over 9 | Very hard |
For example, 4 mEq/L is moderately hard according to this scale. The USGS calls the same water "very hard," because the threshold for this category in their classification is 180 mg/L CaCO₃ (approximately 3.6 mEq/L). Therefore, when choosing a system for a boiler or heating unit, we rely on the measured figure and the requirements of the specific equipment. USGS - American water hardness classification.
The relationship between units is as follows - 1 mEq/L ≈ 2.8 °dH ≈ 50 mg/L CaCO₃. Comparison of hardness units (Table 3, PDF).
A TDS meter assesses the total content of substances dissolved in water. Total hardness is measured separately. If you already have an analysis, our specialist will explain the result to you.
How does limescale affect heating boilers, boilers, and pipes?
Softened water can extend the service life of household appliances. When softened water is supplied to a boiler or the hot water circuit of a heating unit, less limescale accumulates on the heating element and heat exchanger. This promotes efficient heat transfer and reduces the risk of damage caused by scale. USGS - Impact of limescale on heater efficiency and service life.
Heating boiler. In a dual-circuit boiler, water intended for the tap is heated in the heat exchanger. The layer of lime accumulated on its surface hinders heat transfer. When recommending softening for the domestic hot water line, we consider protecting this specific part. The water circulating in radiators moves in a separate, closed circuit. When filling this circuit, we are guided by the specific boiler manufacturer's requirements. Worcester Bosch - Water requirements for closed heating circuits.
Electric boiler. In a storage boiler, scale can accumulate on the heating element, and mineral sediment can settle at the bottom of the tank. If the softener is installed before the cold water inlet of the boiler, already softened water enters the tank for heating.
Plumbing pipes. Especially on the hot water line, over long periods of accumulation, scale can narrow the pipe's internal passage and reduce the flow of water reaching the tap. A softener reduces the formation of new scale in sections where the water from it flows. USGS - How limescale accumulates in water pipes.
What changes regarding skin and hair care? When washing with soft water, less irritating residue may remain on the skin. Researchers at the University of Sheffield observed this effect while studying a common cleansing ingredient (SLS). Minerals from the water also accumulate on hair strands. In a small laboratory study, hair samples washed with hard water contained more calcium and magnesium than samples washed with distilled water. University of Sheffield study - Water hardness and skin irritation · Microscopic hair study - Mineral accumulation on hair strands.
How does resin soften water and why does the system need salt?
Inside the softener is ion-exchange resin. As water passes through, the resin captures calcium and magnesium ions and releases sodium ions into the water in their place. After treating a certain volume of water, the resin needs to be regenerated. The system treats it with brine, then rinses it and discharges the used solution into the sewer. This cycle is called regeneration. In an automatic model, the device controls the cycle, and you periodically fill the salt tank. University of Nebraska guide to water softening (PDF).
How do we choose a softener for your home?
First, we determine where you are experiencing limescale issues and how you use water. For example, if two showers are running simultaneously in the morning, we consider the flow rate required for both when selecting a model. Based on water hardness and daily consumption, we evaluate what volume of resin is suitable and how often the system will need regeneration.
The table shows the characteristics of three models at the same hardness - approximately 3.57 mEq/L (10 °dH). The liters indicated with the model name refer to the resin volume.
| Model and resin volume | Flow capacity | Water between cycles |
|---|---|---|
| FITaqua LUNA-L - water softener, 20 L | 20 L/min | approx. 5,900 L |
| FITaqua LUNA-XL - water softener, 25 L | 25 L/min | approx. 7,400 L |
| FITaqua LUNA-XXL - water softener, 35 L | 25 L/min | approx. 10,300 L |
How much salt does the softener consume per month?
For example, the LUNA-XL consumes an average of 3.8 kg of salt and 130 liters of water per regeneration. In the case of 3.57 mEq/L hardness and 500 liters of consumption per day, this model will undergo regeneration approximately every 15 days. In this example, about 7.6 kg of salt is used for two cycles per month. We will estimate the expected cost for your home during the consultation. The actual cost depends on water hardness, consumption, and system settings. SAFIR - Tabletized salt for water softeners, 25 kg.
Where should the softener be installed?
If the goal is to protect kitchen and bathroom pipes along with the boiler, we look for a place for installation on the main incoming pipe, before the relevant branches. If you only have access to the cold water inlet of the water heater in your apartment, the flow intended for hot water will be treated. During showering, it will mix with regular cold water. When recommending an installation location, our team will check if there is an available power source, a connection to the sewer, and free space above the tank for adding salt.
Consultation with Aquarea
Write to us about where you notice limescale and what you want to protect - the heating boiler, the boiler, or the entire home's pipes. If you already have a water analysis, you can share it with us. We will figure out the rest and explain which model we recommend, where it is best to install it, and what maintenance it will require.
Contact Aquarea for a water softener consultation
Aquarea water softener systems catalog
Read also What is water hardness and how to solve the limescale problem?