Hard water - what is it? How does it affect devices used at home?

What Does It Mean for Water to Be Hard?

The term hard water means that the water contains an excess of magnesium and calcium, additionally iron and manganese. These "healthy-sounding" elemental names, if present in excessive concentration in water, constitute hard water. Going into details - there are 2 types of water hardness - carbonate (i.e., non-permanent - the one that is relatively easy to remove) and non-carbonate (i.e., permanent, which is more difficult to deal with), but for the purposes of our superficial analysis, let's stop there.
In essence, hard water is a natural phenomenon in nature, as it comes from the interior of the earth and can be saturated with various minerals.

Of course, the degree of water hardness can be determined, meaning that it is a characteristic that can occur to varying degrees.

Water Hardness and Standards (Country-dependent)

Standards assume that water in the water supply should maintain a hardness level between 60 and 500 mg CaCO3 per liter. This means that this is the recommendation for water used, but it does not mean that these standards are not exceeded. They are often exceeded both in water from our own source and in water from the mains. Moreover, according to many, even much lower hardness than the critical 500 mg CaCO3/l adversely affects household appliances or elements of the domestic water installation. We are talking here more about the economic significance of hard water, in terms of its impact on the aging of appliances - because in terms of health, hard water is most likely not harmful, although it causes dryness of the skin and hair in some sensitive individuals (although it is generally considered not ideal for hygiene, it is not considered harmful).

In the commercial trade, you can buy water hardness testers, they are quite easily available online and not very expensive. A more expensive but more reliable option is water testing in a specialized laboratory.

What Problems Arise from the Presence of Hard Water?

Our analysis will be subjective and will focus on the problem of central heating or domestic hot water installations, as well as its impact on water-related household appliances. The biggest problem here is the precipitation of boiler scale. This phenomenon is known to everyone, not just plumbers. Chemically speaking, it is calcium and magnesium carbonate, which cause the deposition of a specific sediment. We've all encountered it before.

We all remember the old advertisements for laundry detergents that were supposed to protect the washing machine from scale, in which the specialist showed what washing machine parts with scale deposited on them look like, suggesting the purchase of Calgon. Unfortunately, the advertisement is partly true because scale can indeed deposit to a large extent on the washing machine drum and ultimately damage it. The same applies to other devices.
Similarly, hard water has a very bad effect on the lifespan of a dishwasher, iron, coffee maker, or any other device that has regular or constant contact with water. In particular, scale is often found at the bottom of an electric kettle.

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Which Elements of the Plumbing Installation Are Vulnerable to Scale Resulting from Hard Water?

Virtually every element of the installation wears out over time, and the rate of scale deposition often determines the rate at which components of central heating and domestic hot water age. The most important device that should be protected against boiler scale is the heating boiler. Scale can deposit on its walls, which most of us are unaware of. The problem only becomes apparent after some time, usually when there is a failure of the heat source. It's half okay - if it happens in the summer, the biggest problem occurs when it happens in the middle of severe winter. It would actually be reasonable in our country (considering water hardness) to recommend, which many boiler manufacturers already provide to their customers - to soften the water to increase the boiler's lifespan.

It is worth adding that installations in which boilers operate at higher temperatures are more exposed to scale deposition. Hard water has a tendency to precipitate more scale when heated. It is assumed that the phenomenon of scaling of installations increases significantly when the water in them reaches a temperature of 35 or 40 degrees Celsius - which means that virtually every heating installation is exposed to this (except for underfloor heating installations operating below 30-35°C). However, the higher the operating temperature of the heat source, the faster the problem progresses.

The problem of hard water and scale may also affect heat pumps in the same way. They are theoretically as susceptible to scaling as boilers, with the difference that they often operate with underfloor heating systems and operate at lower temperatures, which matters in the context of what we wrote above.

Scale deposition on pipes, reducing their diameter and throughput, is also a problem. Such scaled installations are characterized by higher consumption of thermal energy - which directly translates into heating costs. It is estimated that heating costs can be higher even by 30-40% compared to a fully healthy installation, although in reality, it will take a few seasons for such an effect to occur.

Particularly dangerous is the scaling of underfloor heating installations. Due to the fact that underfloor heating relies on PEX pipes with a narrow cross-section, it significantly loses its efficiency when scaled. It may happen that parts of the house will be underheated or the floor in some places will not be warm. This is another reason to design underfloor heating to operate with a medium temperature of 28-35°C (according to the widely accepted school of thought) - as this reduces the formation of scale. Using temperatures of 40-45°C on underfloor heating, as some still prefer, may not only be inappropriate for human health but also for the health of the installation itself.

Another quite expensive device that definitely loses a considerable portion of its efficiency, and we would probably want it to be the opposite, is increasingly appearing in Polish homes - UV sterilizer for disinfecting drinking water. The device often appears among people using their own water source (due to a higher risk of E-Coli contamination), but also among those using mains water. Scale over the years is able to even damage the steel reaction chamber of the sterilizer in extreme cases (although let's be honest - we are rather talking about critical points such as welds, welded protrusions, valves, or places where the layer of steel is thinner). However, such a problem may only manifest itself after years (unless we are talking about a device made of low-quality steel) - it is more important to note that scale also settles on the quartz tube, which directly contains the UV-C lamp emitting ultraviolet rays. In this way, we cannot count on 100% efficiency of the device, and we invested in it for a specific reason.

Hard Water and Heat Exchanger / Storage Tank / Boiler

Heat exchangers - both boilers, storage tanks, and plate devices are products that are highly vulnerable. This applies most to boilers and storage tanks - but especially to flow plate heat exchangers (if such a device is present in the system). They are built with extremely thin plates (even 0.25mm thickness), so it is easy to imagine what can happen to such material when it starts to be corroded by scale. The effectiveness of heat exchangers in heat transfer depends on the specific heat exchange surface area (created by the plates). The efficiency of the device depends directly on how large it is. It should be remembered that even if there is no leakage in the heat exchanger - the part of the plate surface covered with scale does not participate in heat transfer. It's as if the surface of the heat exchanger decreases over time, so its efficiency decreases due to scaling. In the final phase - leakage may of course occur inside the device or from the external part. It is worth installing filters before the heat exchanger and cleaning them from time to time - but of course, this does not fully protect the heat exchanger. A scaled heat exchanger often operates very inefficiently, which can result in underheated apartments and/or increased heating costs in the season (because the heat source, e.g., boiler or heat pump, has to work harder). Heat exchanger manufacturers, on the other hand, practically always exclude from the warranty damages caused by scaling, considering them as operational faults not subject to complaint.

To extend the life of a plate heat exchanger in a central heating installation, sometimes cleaning of the exchanger is used - i.e., descaling. Most often with the help of preparations called descalers. Their effectiveness is not always satisfactory - if the scale deposit is already quite large.

How to Fight Hard Water in the Installation

If you live in a region with hard water (the vast majority of our country is located in areas with hard or very hard water), this may concern you. Only less than 10% of our area has water soft enough that it does not have a real impact on the aging of our installation or our water-using household appliances.

A device called a water softener can be installed on the water supply line. It works on the principle of a bed that replaces calcium and magnesium ions - causing scale. These devices are basically maintenance-free. By installing them at the entrance to the house, you can treat the water and protect the entire installation - but there are also smaller versions that can be installed in front of a specific device, e.g., a coffee maker.

Is it Worth Fighting Hard Water?

Naturally, buying a water softener is a cost, for many still a significant expense - around 2500-4500 PLN. The question then arises whether it is worth it since hard water is not a direct health hazard. Of course, it is impossible to determine how quickly our devices age naturally and how many seasons longer they could function if we had soft water. However, it seems rational that in areas with hard and very hard water, this is reasonable. In areas with neutral water - we leave the question open, although it is not excluded. In summary, what do we gain:

- definitely lower heating bills or lower fuel consumption, over the years, the savings in the heating season can amount to between 20-40%. Although if we are talking about a new house, such spectacular losses will certainly not appear in the first or second season. 

- savings on the longer lifespan of devices such as a washing machine, coffee maker, or water kettle, but also fixtures such as showerheads or rain showerheads

- savings on the longer lifespan of a heating boiler or heat pump - in this case, if our heating device avoids failures after years and serves several seasons longer, it can actually be encouraging

- savings on the longer lifespan of a boiler / tank or coils for it

- avoiding the risk of failure of the heat source at an inconvenient time for us or heating elements that prevent the installation from working (e.g., plate heat exchanger). 

This is our subjective assessment, we emphasize that we do not sell any water softening devices. We leave the opinion to you.