What’s In Your Water? Part 3 of Keeping Linens White


By Rich Fitzmorris

What’s In Your Water is part three of my series – How Do I Keep My Linens Looking White? In my previous article, I discussed that water is the most significant factor in cleaning textiles. So let’s explore what constitutes ‘good’ water.

There are six ways to know if the water in your laundry is ‘good’ water. What needs to be considered are – water clarity, water hardness, total dissolved solids, iron, pH and bicarbonates.

Let’s see how each of these qualities help or hinder the water you launder with.

Water Clarity

Clarity or purity of color in water that is used to wash textiles is important. This may seem elementary since most water used in metropolitan areas are ‘cleaned’ by the city. However, we must consider where that water originates. Some municipalities receive water from rivers, others from sewer recycling, and still others from underground aquifers.

The clarity of water is easily tested. It requires taking a sample of water that enters the building or laundry and filling a clean clear glass container. Secure the container with a top to keep debris out – and wait. Allow the water to sit in the glass container away from direct sunlight for 24-48 hours. Then, if there are suspended particles or if the water clouds, it is an indication that the water needs to be filtered and / or treated.

Water Hardness

The simple definition of water hardness is the amount of dissolved calcium and magnesium in the water. Hard water is high in dissolved minerals, both calcium and magnesium. In hard water, alkaline detergents react with the calcium (which is relatively high in hard water) to form scale. When using hard water, more detergent is needed to clean goods, and those goods will suffer in the areas of whiteness and brightness.

Long-term movement of hard water through a pipe can result in what is called scale buildup. Water pipes gradually close up resulting in less water pressure and volume through the pipe. This results in slower fill times and chunks of scale breaking loose causing plugged line screens and damaged water valves on washing equipment.

The hardness of water should be considered for both hot and cold water. Water hardness scales, such as the chart I created below, will give you an indication of the ‘hardness’ of the water you’re using. Although others may feel that soft water can be considered water with less than 1 grain of hardness – I disagree. I feel that soft water has 0 grains of hardness – there is no such thing as ‘almost soft’ or ‘nearly soft’.

 

Water Hardness Scale
Grains Per Gallon Milligrams Per Liter (mg/L) or Parts Per Million (ppm) Classification
0 0 Soft
1 – 1.5 17.1 – 26 Mildly Soft
1.5 – 3.0 26 – 51 Slight Hard
3.5 – 7.0 120 – 180 Moderately Hard
7.5 – 10.0 128 – 171 Hard Water
Over 10.0 171 + Very Hard

 

Occasionally you will find a laundry softening water before it reaches the hot water heater to keep scale from building up in the heater coils or hot water tank. But many people make the mistake of not softening their cold water. Cold water that is un-softened will redeposit soil and hard water salts back onto the textiles making them dull and lack brightness.

Chemical companies can use specific chemicals to help control this issue and acid sour will help strip hardness from textiles, but this a cost that is not necessary and has a costlier effect on the textile’s life expectancy, or linen replacement cost.

I feel that institutional, commercial or cooperative laundries should soften all water with a system that is sufficiently sized to handle the water needs of the laundry.

Total Dissolved Solids

Total Dissolved Solids (TDS) also affect water quality and the washing process. TDS are the total amount of mobile charged ions, including minerals, salts or metals dissolved in a given volume of water, expressed in units referred to as parts per million (ppm). TDS are basically the total content of inorganic and organic substances that are present and suspended in water.

Dissolved solids are too small to be filtered from water. This poses a difficult problem for laundries. High TDS effect the cleaning process during the chemical rinse process – especially when considering alkali based detergents or when alkali is used as a builder in the chemical mixture used for cleaning.

When you have very high TDS, you will need to use a large amount of acid/sour to adjust the pH of the textiles back to neutral or slightly acidity. Although there are different opinions as to the number of TDS that are acceptable, I feel that TDS over 500 ppm can and will create problems in textile cleaning, build-up on equipment, and textile life span.

Correcting TDS prior to the wash process is less expensive than waiting until problems occur.  Sediment filtration and Carbon filtration do not remove TDS. Reverse Osmosis (RO) purification, Purification by Distillation and Deionization will remove TDS.

If water is stored in a very large stainless steel tank, acid can be used to ‘eat’ or dissolve the suspended materials in the water. The need to be accurate in the adjustment of pH is critical to not overshoot the acid used. There are acids that are safer and can more easily be adjusted to achieve a pH around 7.2 to 7.5.

Iron Content

In a previous article I commented on iron and iron staining. With concentrations higher than 0.3 ppm, iron water can cause dulling of white textiles when a neutralizer is not used in the last rinse cycle.

Generally .5 ppm of iron will stain and discolor white textiles. Chlorine is not a good choice for washing textiles when there is a significant amount of iron present in the water. The best way to wash under the conditions where iron is present is to use oxygen bleaches.

When using commercial laundry equipment, an iron removing sour can strip iron or control its presence depending upon the concentration of the bath, and lower pH value of the water in the bath. When iron is causing significant textile cleaning and whiteness problems in a laundry, I recommend installing a water softening system that utilizes de-iron salt pellets.

A water softener can remove up to .2-.3 ppm of iron. This approach has great benefits for cleaning, whitening, and maintaining tensile strength of the textile fabric over more costly chemical alternatives.

Water Supply pH

How does pH affect washing quality? It is essentially a measure of the relative acidity or alkalinity in water. pH is measured on a scale of 0 to 14. A pH of 0 is extremely acidic and pH of 14 is extremely alkaline. The pH scale is logarithmic which means that each point on the scale equals a ten-fold difference.

For example, a solution with a pH of eight is 10 times more alkaline than a pH of seven. However the pH of incoming laundry water is only important if the pH is buffered by bicarbonate at levels high enough that chemistry is impeded in the washing and rinsing of textiles.

So what is a good pH level for incoming water? The answer is any number between 7.0 and 9.0 with a low bicarbonate level.

Bicarbonate in Water

What is Bicarbonate in water? It is a natural occurrence. In nearly all circumstances, bicarbonate water, which is alkaline water, is the result of soil compositions through which water leaches. Soil and rocks contain carbonate, bicarbonate, silicates and phosphates that are natural to the earth’s soils. When washing textiles bicarb is alkalinity in water that resists or is less effected by rinsing and acid treatments. This resistance to change pH in the wash/rinsing cycles makes for reducing the pH difficult in the wash formula process. This capacity is commonly known by technicians as buffering capacity.

Water that has near 0 bicarbonate allows for less rinse water to be used and most often fewer rinse cycles. Ranges of bicarb in water can vary greatly, but for this purpose I will describe what I consider to be very good to high bicarb conditions for laundering. Very good water would be less than 50 ppm. High bicarb would be considered greater than 300 ppm.

In conclusion, below you’ll find what I consider to be the components of good laundering water.

  1. Clarity             Crystal Clear water with no sediments.
  2. Hardness       Very Good – Softened – 0 hardness; Good – <1.5 grains of hardness
  3. TDS                Very Good – <50 ppm; Good – <150 ppm
  4. Iron                 Very Good – 0 ppm; Good – .3ppm
  5. pH                   Very Good 7.0-7.5; Good 7.6-8.0
  6. Bicarbonate  Very Good <20ppm; Good <100 ppm

 

*  Next month we will discuss how to maintain linen brightness, water reuse and how water reuse affects the quality of textile washing.

Image credit: White towels: (C) Can Stock Photo Inc. / irabel8

 

ABOUT THE AUTHOR:

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Rich Fitzmorris is a veteran of the laundry industry. Rich retired after 42 years at Sunburst Chemicals. Although he headed up various Sunburst business sectors throughout his career, prior to retiring, Rich was Senior Vice President Professional Textile Chemistry, where he oversaw the company’s Large Laundry Division, laundry product development and chemical technology. Presently, he is putting his experience to work consulting in the areas of industrial and commercial laundry wash processes, chemistry, production, utilities, formulas and cost reductions.