Understanding water before correcting the wash process
By Ali Abdul Azeez
Founder and Editor in Chief
A lifelong student of professional textile care since 1983
EDITORIAL INTRODUCTION
Water is the largest working material used in most professional laundry processes. It carries heat, wets the textile, transports chemicals, loosens and suspends soil, supports rinsing, and removes dissolved and particulate contamination from the load.
Yet water is often treated as though it were a fixed and neutral ingredient. It is neither.
Two laundries may use the same machine, detergent, programme, temperature, and textile classification and still obtain different results because their incoming water is different. Even one laundry may experience changing results when the water source, season, storage condition, treatment system, or operating demand changes.
For this reason, water should not be considered only as a utility purchased by the cubic metre. It should be managed as a process material whose quality, quantity, temperature, pressure, treatment, and discharge influence the complete textile-care result.
The Founding Edition establishes the publication’s mission and editorial principles. This issue applies them to one technical subject: understanding and controlling water in professional textile care.
Before increasing chemicals, extending wash time, raising temperature, or blaming the machine, understand the water.
1. What Water Must Do in a Wash Process
In a controlled professional wash process, water performs several connected functions:
Wetting – Water must reach the fibre and the soil. Surface tension, textile construction, finishes, oils, and trapped air can delay wetting.
Transporting chemistry – Builders, surfactants, alkalis, bleaches, neutralisers, disinfecting agents, and finishing products must be distributed uniformly.
Transferring heat – Water carries thermal energy into the load and helps maintain the programmed temperature.
Removing soil – Dissolved soil and suspended particles must move away from the textile and remain controlled until drainage.
Rinsing – Residual alkalinity, detergent, loosened soil, and treatment chemicals must be diluted and removed.
Protecting textiles and equipment – Suitable water quality helps limit redeposition, mineral scale, staining, corrosion, and avoidable chemical consumption.
Water therefore influences cleaning quality from the first flush to the final rinse.
2. Water Quality Is More Than Hardness
Hardness is one of the most important water measurements in laundering, but it is not the complete water profile. A professional evaluation may include:
Total hardness
pH
Alkalinity
Iron and manganese
Total dissolved solids
Conductivity
Turbidity or suspended matter
Colour and odour
Chloride and sulfate where corrosion or source-water concerns exist
Microbiological quality where hygiene risk requires control
Temperature, pressure, and flow at the point of use
No single number can describe the complete suitability of water for a laundry process.
3. Hardness: Calcium and Magnesium
Water hardness is primarily caused by dissolved calcium and magnesium. It is commonly expressed as milligrams per litre of calcium carbonate, written as mg/L as CaCO3. Parts per million and mg/L are approximately equivalent for dilute water solutions.
The United States Geological Survey uses the following general descriptive classification:
| Hardness as CaCO3 | General description |
|---|---|
| 0-60 mg/L | Soft |
| 61-120 mg/L | Moderately hard |
| 121-180 mg/L | Hard |
| More than 180 mg/L | Very hard |
These categories describe source water; they are not automatic laundry-process specifications.
The acceptable hardness at the washer must be established in consultation with the detergent supplier, equipment manufacturer, textile requirements, operating temperature, and required finish quality.
Why Hardness Matters
Calcium and magnesium can react with some cleaning ingredients, reduce detergency, form insoluble deposits, promote greying or harshness, and contribute to scale in pipes, valves, heating surfaces, boilers, and heat exchangers.
The practical consequences may include:
Higher chemical demand
Reduced soil removal
Mineral deposition on textiles
Loss of whiteness or brightness
Harsh handle
Increased risk of redeposition
Scale formation and reduced heat-transfer efficiency
Restricted water flow
More frequent maintenance
Inconsistent results between batches
Adding more detergent without measuring hardness may hide the symptom temporarily while increasing cost, rinsing demand, dissolved load, and wastewater burden.
4. pH and Alkalinity Are Related, but Not Identical
pH describes how acidic or alkaline the water is at the moment of measurement.
Alkalinity describes the water’s capacity to resist a fall in pH, commonly due to bicarbonate, carbonate, and hydroxide species. In practical terms, alkalinity influences how the water responds when process chemicals are added.
Two water samples can have a similar pH but behave differently during washing because their alkalinity is different.
Incoming water pH should therefore not be used as a substitute for measuring wash-bath pH or final-rinse condition. Process control should be based on measurements taken at the correct point in the cycle and interpreted alongside chemical dosage, load classification, water ratio, temperature, and time.
The U.S. Environmental Protection Agency lists pH 6.5-8.5 as a secondary guideline for drinking water. This is an aesthetic and technical water-supply reference, not a universal laundry-process target. Professional wash stages may intentionally operate outside this range under controlled chemical programs.
5. Iron and Manganese: Small Quantities, Visible Damage
Iron and manganese can enter water naturally or through corrosion in wells, tanks, pipes, and distribution systems.
Iron may contribute to yellow, orange, or reddish staining. Manganese may produce grey, brown, or black staining. Oxidising chemicals can make dissolved metals more visible by converting them into coloured or insoluble forms.
The EPA secondary drinking-water guidelines list:
Iron: 0.3 mg/L
Manganese: 0.05 mg/L
These values are not textile guarantees. Sensitive white goods and high-value textiles may reveal quality problems at conditions that require site-specific investigation.
When unexplained staining appears, the response should not begin with stronger bleach. The source should be investigated systematically:
Test the incoming water.
Compare raw and treated water.
Inspect storage tanks and distribution lines.
Check corrosion, stagnant branches, and recent plumbing work.
Examine steam and condensate where they contact textiles or process water.
Review chemical compatibility before applying oxidising agents.
6. Total Dissolved Solids and Conductivity
Total dissolved solids (TDS) is the combined concentration of dissolved substances in water. It does not identify which substances are present.
Conductivity measures the water’s ability to conduct electricity and is often used as a rapid indicator of ionic content. Conductivity can be useful for trending water consistency, softener performance, rinse progress, or changes in source water, but it is not a direct substitute for a complete chemical analysis.
The EPA secondary guideline for TDS in drinking water is 500 mg/L. Again, this is not a universal process limit for laundering. The effect of dissolved solids depends on their composition, the textile, the wash chemistry, the reuse system, and the required quality.
A rising conductivity trend can be valuable even before the operator knows the exact cause. Trend changes should trigger investigation rather than automatic chemical adjustment.
7. Turbidity, Colour, and Suspended Matter
Water may appear clear while still containing dissolved minerals. It may also carry suspended particles from the source, storage tank, pipework, treatment media, or maintenance activity.
Turbidity and visible matter can contribute to:
Textile discolouration
Specks or deposits
Filter blockage
Valve and nozzle problems
Unstable chemical dosing
Increased microbial risk in poorly controlled storage systems
Incoming-water filters, tanks, and distribution lines require inspection and planned maintenance. A water-treatment plant cannot deliver stable quality if downstream storage and pipework recontaminate the treated water.
8. Water Treatment Must Match the Problem
Water treatment should be selected only after the raw water has been analysed and the process requirement has been defined.
Possible treatment stages include:
Screening and sediment filtration
Activated carbon
Water softening by ion exchange
Iron or manganese removal
Cartridge or bag filtration
Membrane filtration
Reverse osmosis
Dealkalisation or demineralisation
Ultraviolet or chemical disinfection where justified
Storage, circulation, and pressure control
Each technology solves particular problems and introduces its own operating requirements. For example:
A softener reduces calcium and magnesium hardness but does not necessarily reduce total dissolved solids.
Activated carbon can reduce chlorine and some organic contaminants but requires hygienic maintenance.
Reverse osmosis can reduce many dissolved substances but produces reject water and requires pretreatment, membrane care, pressure, monitoring, and a plan for storage and distribution.
Filtration can remove particles but does not automatically remove dissolved minerals.
The correct question is not, “Which treatment system is best?” It is:
Which combination of treatment stages will reliably convert our actual source water into the quality required by our actual process?
9. Softener Control: Do Not Wait for Poor Washing
A water softener must be monitored as process equipment. It should not be treated as a silent tank that receives salt occasionally.
Good control includes
Testing hardness before and after the softener
Confirming regeneration frequency and capacity
Checking salt level and salt quality
Preventing salt bridging
Inspecting the brine system, injector, valves, and drain
Reviewing flow demand and peak loading
Checking for hardness breakthrough
Recording maintenance and test results
Providing a response plan when treated-water hardness rises
Testing only the raw water does not prove that the washer receives softened water. Sampling should occur at defined points, including the point of use where practical.
10. Water Quantity, Level, Flow, and Pressure
Water quality alone cannot correct an unsuitable water quantity.
Too little water may cause:
Poor dilution
Restricted mechanical action
Inadequate chemical distribution
Soil redeposition
Poor rinsing
Excessive textile-to-textile friction
Too much water may cause:
Unnecessary chemical dilution
Reduced mechanical action in some washer designs
Longer filling and heating time
Higher water, energy, and wastewater cost
Low supply pressure, undersized pipes, blocked strainers, slow valves, or simultaneous peak demand can change the real cycle even when the programmed water level appears correct.
Operators should compare programmed conditions with actual fill time, level, temperature, drainage, and load behavior.
11. Temperature Is Part of Water Management
Hot water carries a significant energy cost. Temperature should be selected for the textile, soil, chemistry, hygiene objective, equipment, and validated process-not by habit.
Lower-temperature processes can reduce energy demand when supported by suitable chemistry, time, mechanical action, and verification. Higher temperature may still be required for particular soils, textiles, or validated hygiene programs.
The professional objective is not always the lowest temperature or the highest temperature. It is the lowest responsible total resource use that consistently achieves the required quality and hygiene outcome without damaging the textile.
12. Rinsing Is Controlled Dilution
Rinsing removes what the wash process has released. Its effectiveness depends on:
Water quality
Water quantity
Number and sequence of rinses
Drainage efficiency
Extraction between stages
Load size and textile absorbency
Residual chemistry and soil
Final pH or alkalinity requirement
A final rinse that looks clear is not necessarily chemically complete.
Where appropriate, the laundry may monitor final-rinse pH, conductivity, alkalinity, or another validated indicator. The chosen control must relate to the textile’s intended use and the chemical programme.
13. Water Reuse and Recycling
Water reuse can reduce consumption, energy demand, and discharge, but reuse must be engineered rather than improvised.
Questions include:
Which streams are suitable for recovery?
What soil, colour, chemical, dissolved-solid, and microbiological load do they contain?
What treatment is required before reuse?
In which wash stage can the recovered water be used safely?
How will cross-contamination be prevented?
How will concentration of salts and chemicals be controlled?
What happens during system failure or maintenance?
How will recovered-water quality be monitored?
Reused water should have a defined specification for its intended stage. It should not be described simply as “clean water.”
14. Build a Water Quality Control Plan
A practical water-control plan should identify:
| Control point | What to monitor | Typical reason |
|---|---|---|
| Raw incoming water | Hardness, pH, conductivity/TDS, iron/manganese where relevant, turbidity | Understand the source and detect change |
| After treatment | Parameter the system is designed to control | Confirm treatment performance |
| Storage tank | Cleanliness, turnover, cover, sediment, microbial risk where applicable | Prevent recontamination |
| Point of use | Hardness, pressure, temperature, flow or other critical parameters | Confirm what the washer actually receives |
| Selected wash stages | pH, temperature, conductivity or chemical concentration where validated | Control the process |
| Final rinse | pH, conductivity, alkalinity or other validated acceptance indicator | Confirm removal and finishing condition |
| Recovered water | Stage-specific quality parameters | Protect textiles and prevent concentration or contamination |
The plan should state
Sampling location
Test method
Frequency
Acceptable operating range
Person responsible
Recording method
Corrective action
Escalation requirement
The limit should come before the test result. A number without an agreed response is observation, not control.
15. A Disciplined Troubleshooting Sequence
When wash quality changes, avoid changing several variables at once.
Use a controlled sequence:
Define the defect clearly.
Confirm load classification and loading ratio.
Verify the programme actually delivered.
Check water source, pressure, fill, level, temperature, and drainage.
Test raw water, treated water, and point-of-use water.
Confirm chemical identity, concentration, dosage, and injection timing.
Review mechanical action and machine condition.
Inspect rinsing and extraction.
Compare the result with historical records.
Change one controlled variable at a time where safe and practical.
Record the result and retain the learning.
This method protects the laundry from “solution by guesswork.”
16. Ten Questions Every Laundry Manager Should Be Able to Answer
What is the source of our water?
What is its hardness, and how stable is it?
Which other water parameters are critical for our textiles and chemistry?
What treatment do we use, and what exactly is it designed to remove?
How do we prove the treatment system is working?
Does water quality change between treatment and the washer?
Are pressure, flow, temperature, fill time, and drainage consistent?
What are our final-rinse acceptance criteria?
Which water streams are measured, reused, discharged, or lost?
Who acts when a result moves outside the agreed operating range?
If these questions cannot be answered, water is not yet under professional control.
Conclusion
Water is not simply the background of laundering. It is an active part of chemistry, mechanics, heat transfer, rinsing, textile protection, equipment reliability, energy use, cost, and environmental responsibility.
The purpose of water management is not to chase one “perfect” number. It is to understand the complete water system, define the quality required at each stage, measure consistently, and act before variation becomes textile damage or customer dissatisfaction.
Professional textile care begins with listening-to the customer, to the textile, to the process, and to the evidence.
It also begins with water.
EDITORIAL & PROFESSIONAL PRACTICE DISCLAIMER
Commitment to knowledge, professional integrity, and best practice
The Science of Professional Textile Care is an independent educational and professional knowledge initiative published by Laundry-Master.com. It has been established to advance textile-care standards through the responsible sharing of practical experience, technical knowledge, research, innovation, and recognised industry best practices.
The information in this publication is intended for education and professional reference. Every reasonable effort is made to present content accurately and responsibly. However, textile care is a continuously evolving discipline. Machinery, chemicals, textiles, care instructions, standards, environmental requirements, safety obligations, and manufacturers’ recommendations may change.
Readers must exercise professional judgement and verify the suitability of information for their own equipment, textiles, water, chemicals, workforce, customer requirements, operating conditions, and local laws.
This publication does not replace:
Equipment or chemical manufacturers’ instructions
Textile manufacturers’ care requirements
Validated healthcare or infection-control procedures
Workplace safety requirements
Environmental permits or discharge conditions
Applicable laws, codes, and regulatory standards
Site-specific risk assessments and operating procedures
Independent legal, engineering, chemical, or safety advice
Any numerical value included for explanation must be interpreted in its stated context. Drinking-water classifications or guidelines are not automatically laundry-process limits. Operating targets should be agreed using appropriate testing, supplier guidance, process validation, textile requirements, and applicable regulations.
Laundry-Master.com, the Publisher, Editor, contributors, and advisors accept no liability for direct, indirect, incidental, or consequential loss, damage, injury, or non-compliance arising from the interpretation or application of information in this publication.
Constructive corrections, additional evidence, and responsible professional discussion are welcomed. Where an error or significant new development is identified, the publication may issue a correction or update.
COMING IN VOLUME 1 | ISSUE 2
Applied Water Treatment and Quality Control
The next issue will build on these fundamentals with detailed guidance on treatment-system selection, monitoring, maintenance, and corrective control.
Planned topics include
How to read a professional water analysis report
Selecting sampling points and test frequency
Softener sizing, regeneration, salt use, and hardness breakthrough
Filtration, activated carbon, iron removal, and membrane systems
Reverse osmosis: benefits, limitations, reject water, and maintenance
Storage tanks, circulation, hygiene, and point-of-use quality
Water reuse: risk assessment and stage specific specifications
Building a water treatment logbook and corrective action system
Connecting water quality with chemical dosage, boilers, steam, and finishing
Future scope may be adjusted as evidence, professional contributions, and industry priorities develop.
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