Laundry Water Treatment: Limescale and Efficiency in Textiles

The chemical bill climbs a little every month, heating elements fail more often than expected, there is build-up in the steam boiler and unplanned stoppages disrupt production. The technical manager usually takes these items separately: talks to the chemical supplier, calls a service, plans boiler maintenance. Yet behind that picture there is often one common variable, and laundry water treatment comes up at exactly this point.

In this guide we take up three effects of water quality in an industrial laundry: limescale build-up on equipment, chemical and energy consumption, and repeatability of process. The aim is not to make claims about washing results but to show in measured terms how water affects running costs and the continuity of equipment.

Why Is Water Quality Decisive in a Laundry?

Water plays two roles in a laundry: it is the main component of the washing process and a working condition for the equipment. Hard water deposits limescale on heated surfaces, can raise consumption by lowering the performance of cleaning chemicals, and can lead to variability in washing results.

That dual role sets the subject apart from other business costs. In a laundry, chemicals are chosen carefully, the machine park is set up with care and programme times are optimised. Water, the most heavily used input of all, is meanwhile treated in most plants as something that is simply there.

Yet the minerals in the water leave a trace on every surface they touch. They build up in heated areas, interact with chemicals and can leave residue on the fabric after rinsing. All of these are measurable results with a calculable cost.

In a laundry water treatment assessment is therefore not a matter of comfort but a business decision. How often the equipment fails, how predictable chemical consumption is and how often there are stoppages all depend on this heading.

The relationship between water use in commercial sites and operating performance is taken up in official sources too; the US Environmental Protection Agency’s water use by facility type resource offers a general framework on water management in different types of site.

How Does Hard Water Affect the Washing Process?

The hardness ions in water interact with the active ingredients of detergents and cleaning chemicals. That interaction can reduce foaming and call for more chemical to be used to get the same result. Minerals left in the rinse water can also leave residue on the fabric.

This can be explained by basic water chemistry, and at industrial scale the effect is clearly felt. An increase in dose that goes unnoticed in a domestic machine shows in the annual budget of a laundry running all day.

The mechanism works like this: the calcium and magnesium ions in the water bind part of the active ingredients of the cleaning product. The part that is bound no longer performs its cleaning function; the amount left may not give the performance expected.

On the operator’s side the answer to that is a higher dose. When the expected result is not obtained the amount of chemical is raised, it becomes a habit, and consumption rises quietly. The problem is usually blamed on the product; the source, though, is the water.

The second effect is on the rinsing side. Minerals left in the rinse water can leave residue in the fabric fibres; that can lead to a need for extra rinsing and a rise in water consumption. The first aim of a laundry water treatment build is to remove those two effects.

Limescale in Industrial Washing Machines

The calcium and magnesium in water precipitate on heated surfaces and form a layer of limescale. Because that layer lowers heat transfer, the machine reaches its target temperature later; the programme takes longer, energy consumption rises and the load on the heating element increases.

Industrial washing machines run all day and at high temperatures. Those two conditions create the most favourable environment for build-up; the process is markedly faster than in domestic use.

The second and more critical consequence of lost heat transfer is that the temperature of the heating element itself rises. When the heat cannot be transferred to the water, the element is strained; that accelerates material fatigue and raises the frequency of failures.

The points affected are these:

We took up the mechanism of limescale on heat transfer and how it advances in equipment in a separate article; the technical background is what hard water does to equipment article. The focus here is industrial scale.

Figure 1: The points affected by limescale build-up in an industrial laundry

Limescale in the Steam Boiler, Irons and Press Lines

In steam generation the quality of the feed water is directly decisive. Because the water evaporates completely, the minerals in it stay inside the boiler and form scale. On iron and press lines the minerals carried can leave marks on the fabric and create build-up in the equipment channels.

The steam side is the part of a laundry most sensitive to water quality. In other equipment the water passes through and some of it leaves the system; in a boiler the water evaporates and the minerals stay behind. The rate of build-up is therefore markedly higher.

We took up in a separate article the criteria on which boiler feed water is assessed and the idea of process water; for the framework see our process water article .

The chemical control of scaling is a separate heading and comes up on membrane systems in particular. We took up the mechanism and the conditions of application in our scale inhibitor chemicals article .

In plants with a steam line, a laundry water treatment build is planned to cover not only the washing machines but the boiler feed line. The needs of the two lines can differ; that distinction is clarified at the engineering stage.

The Variability Seen in Fabric and Washing Results

In hard water, mineral residue can form on the fabric after rinsing; operators may report a stiff feel and dulling. When the water quality changes seasonally or by region, variability can be seen in washing results. Water quality that is under control supports repeatability of process.

Measured language is needed in this section. We make no firm claims about washing results; those are matters that require proof. What can be said is this: a variable input makes standardising a process harder.

Consistency matters in an industrial laundry. A wash carried out with the same programme, the same chemical and the same timing is expected to run under similar conditions. If one of the inputs varies through the day or with the season, that variability can carry through to the process.

One of the inputs that can be fixed is water. When hardness is reduced at source, the water the plant uses becomes largely independent of seasonal fluctuation in the mains.

Operator feedback should be assessed in that framework too. In plants with high hardness, reports of a stiff feel to the fabric and residue after rinsing are commonly met; but these are observations requiring measurement, not a guarantee of result.

Chemical and Energy Costs

Because the performance of cleaning chemicals can fall in hard water, consumption can rise. At the same time, build-up on heated surfaces can raise the energy bill by reducing heat transfer. When water quality is brought under control, those two items become more predictable.

For the business those are two constantly repeating costs. The investment in equipment is a one-off; chemicals and energy are consumed every day, every shift.

The headings affecting the cost are these:

The last row of that table is often left out of the calculation. A longer programme time means less work done with the same machine park; that is lost capacity directly.

The size of those items varies from plant to plant; the hardness of the water, the number of machines and the daily washing volume are what decide it. It would not be right to promise a percentage here. A laundry water treatment investment should be calculated from the site’s own data.

Which Stages Are Used in a Laundry Water Treatment System?

A typical build contains these stages: sediment or sand filtration, activated carbon, water softening and, where needed, reverse osmosis. Each stage targets a different problem and protects the next. Which stages are needed is established from the water analysis result.

The table below matches the problem met in the plant with the right stage:

The first link in the chain is pre-filtration; it protects the stages behind it from particle load. Where the particle load is limited, industrial-type pre-filter sets may be enough, while at a high load sand units with automatic backwashing come into play.

Where chlorine and organic load are involved, high-capacity carbon units both reduce the sensory effect and protect the stages behind them.

The decisive stage, though, is softening, because most of the problems in a laundry come from hardness. For needs at this scale, industrial softening systems are used, and the capacity is established from how heavily the plant works.

Figure 2: A staged water treatment installation on a laundry line

Why Is Uninterrupted Soft Water Critical?

Softening systems regenerate regularly to renew the saturated resin. In a single-tank build, hard water can pass down the line for that period. In laundries running continuously that risk is unacceptable; twin-tank tandem builds are therefore preferred.

This is the design detail most often skipped in an industrial laundry. The system is installed and the capacity chosen correctly; but the regeneration window is not taken into account.

The problem appears like this: regeneration is generally programmed for the night hours. But in a plant running three shifts there is no “quiet hour”. Either hard water passes during regeneration, or the cycle is put off and the resin stays saturated.

A tandem build removes that dilemma. There are two tanks; when one goes into regeneration the other stays in service. Softened water is thereby delivered to the line without interruption.

We took up how the cycle works — backwash, brine draw and rinse steps included — in a separate article; for the details see regeneration cycle .

Built for plants running continuously, twin-tank tandem softening systems are, in a laundry water treatment project, usually considered an essential component.

How Is the System Sized?

In sizing, the number and capacity of the machines, the daily washing volume, simultaneous use at peak hours, the steam line requirement and the inlet water quality are assessed together. The system should be chosen not for the daily average but for demand at the busiest hour.

Demand in a laundry is not spread evenly. In a hotel laundry the morning hours, in a hospital laundry the shift changes, and in dry cleaning the weekend peak stand out. A system chosen on the average falls short at exactly those hours.

The headings to assess are these:

1. Set Out the Machine Park

   The number and capacity of the machines define the total load the system has to meet.

2. Establish the Daily Volume

   The daily washing volume is the basic input for total water consumption and resin capacity.

3. Calculate the Peak Hour

   How many machines run at the same time? That is the real load the system has to meet.

4. Assess the Steam Line

   Where there is a boiler feed line its requirement is calculated separately; the quality expected can be different.

5. Define the Working Pattern

   The shift arrangement and the need for uninterrupted running determine the decision on a tandem build.

6. Confirm the Infrastructure

   The equipment layout, access to the salt tank, the drain connection and the power supply should be settled in advance.

We took up the general logic of a capacity calculation and what to watch for at business scale in a separate article; you can read the approach in our industrial-type system selection guide . The final capacity is always established from the water analysis and how busy the business is.

The starting point of the process is measurement. Without knowing the hardness of the water and its other parameters, which stages are needed and which capacity suits cannot be established. How a sample is taken water analysis guide .

Maintenance and Continuity of Operation

Once the system is installed, continuity depends on maintenance. The salt in the softening stage has to be watched, the pre-filters renewed on time, periodic checks made and the water analysis repeated. Because a stoppage in a laundry means lost work directly, maintenance should be tied to a service plan.

The most common reason maintenance slips in a business is not technical but organisational: who checks what, and when, has not been settled. When that question goes unanswered, the salt runs out, the filter change is put off and the system does not perform as expected.

The headings to follow regularly are these:

• The salt level: When the salt in the softening stage runs out, the system cannot renew itself and hard water passes down the line.
• Renewing the pre-filters: The stages are renewed when saturated; the interval varies with the inlet water quality.
• Monitoring pressure and flow: The pressure difference between stages is an early indicator of blockage.
• Checking the outlet quality: Following the hardness is the most practical way of confirming the system is working properly.
• Periodic service: Valve settings and the state of the stages are checked regularly by a specialist.
• Repeating the analysis: The character of the inlet water can change seasonally; the dosage and capacity are reviewed.

The choice of product matters on the salt side too. A treatment salt made for this application and of suitable purity protects both the tank and the valve from residue and reduces how often maintenance is needed.

Water Point Su Arıtma Teknolojileri operates from Esenyurt, İstanbul under its founder Ali Genç, with more than 20 years of experience in the sector.

Broad spare parts cover means continuity for plants running continuously. When maintenance is due, being able to obtain the part keeps the system running without interruption.

Frequently Asked Questions