FURTHER INFORMATION

water hardness, scale and its effects...

Water described as "hard" is high in dissolved minerals, specifically calcium and magnesium. Hard water is not a health risk, but a nuisance because of mineral build-up on fixtures and poor soap and/or detergent performance.

Sources of Hardness Minerals in Drinking Water
Water is a good solvent and picks up impurities easily. Pure water - tasteless, colourless and odourless - is often called the universal solvent. When water is combined with carbon dioxide to form very weak carbonic acid, an even better solvent results. As water moves through soil and rock, it dissolves very small amounts of minerals and holds them in solution. Calcium and magnesium dissolved in water are the two most common minerals that make water "hard". The degree of hardness becomes greater as the calcium and magnesium content increases and is related to the concentration of multivalent cations dissolved in the water.

Indications of Hard Water
Hard water interferes with almost every cleaning task from laundering and dishwashing to bathing and personal grooming. Clothes laundered in hard water may look dingy and feel harsh and scratchy. Dishes and glasses may be spotted when dry. Hard water may cause a film on glass shower doors, shower walls, bath tubs, sinks, taps, etc. Hair washed in hard water may feel sticky and look dull. Deposits in pipes may reduce water flow.

Dealing with hard water problems within the home can be a nuisance. The amount of hardness minerals affects the amount of soap and detergent necessary for cleaning. Soap used in hard water combines with the minerals to form a sticky soap curd. Some synthetic detergents are less effective in hard water because the active ingredient is partially inactivated by hardness, even though it stays dissolved. Bathing in soap with hard water leaves a film of sticky soap curd on the skin. The film may prevent removal of soil or bacteria. Soap curd interferes with the return of skin to its normal, slightly acid condition, and may lead to irritation. Soap curd on hair may make it dull, lifeless and difficult to manage.

When doing laundry in hard water, soap curds lodge in fabric during washing to make fabric stiff and rough. Incomplete soil removal from laundry causes graying of white fabric and the loss of brightness in colours. A sour odour can develop in clothes. Continuous laundering in hard water can shorten the life of clothes.

In addition, soap curds can deposit on dishes, bathtubs and showers, and all water fixtures.
Hard water also contributes to inefficient and costly operation of water-using appliances. Heated hard water forms a scale of calcium and magnesium minerals that can contribute to the inefficient operation or failure of water-using appliances. Pipes can become clogged with scale that reduces water flow and ultimately requires pipe replacement.

Potential Health Effects
Hard water is not a health hazard. In fact, the National Research Council (National Academy of Sciences) states that hard drinking water generally contributes a small amount toward total calcium and magnesium human dietary needs. They further state that in some instances, where dissolved calcium and magnesium are very high, water could be a major contributor of calcium and magnesium to the diet.

Researchers have studied water hardness and cardiovascular disease mortality. Such studies have been "epidemiological studies", which are statistical relationship studies.

While some studies suggest a correlation between hard water and lower cardiovascular disease mortality, other studies do not suggest a correlation. The National Research Council states that results at this time are inconclusive and recommends that further studies should be conducted.

Testing
If you are on a municipal water system, the water supplier can tell you the hardness level of the water they deliver. If you have a private water supply, you can have the water tested for hardness. Most water testing laboratories offer hardness tests for a fee, including the Environmental Quality Center. Also many companies that sell water treatment equipment offer hardness tests. When using these water tests, be certain you understand the nature of the test, the water condition being measured, and the significance of the text results. An approximate estimate of water hardness can be obtained without the aid of outside testing facilities. Water hardness testing kits are available for purchase through water testing supply companies. If more accurate measurements are needed, contact a testing laboratory.

Interpreting test results
The hardness of your water will be reported in grains per gallon, milligrams per litre (mg/1) or parts per million (ppm). One grain of hardness equals 17.1mg/1 or ppm of hardness.

The Environmental Protection Agency (EPA) establishes standards for drinking water which fall into two categories - Primary Standards and Secondary Standards.

Primary Standards are based on health considerations and Secondary Standards are based on taste, odour, colour, corrosivity, foaming and staining properties of water. There is no Primary or Secondary standard for water hardness. The U.S Department of Interior and the Water Quality Association classify water hardness as follows

Options
There are two ways to help control water hardness: use a packaged water softener or use a mechanical water-softening unit.

Packaged water softeners are chemicals that help control water hardness. They fall into two categories: precipitating and non-precipitating.

Precipitating water softeners include washing soda and borax. The products form an insoluble precipitate with calcium and magnesium ions. The mineral ions then cannot interfere with cleaning efficiency, but the precipitate makes water cloudy and can build up on surfaces. Precipitating water softeners increase alkalinity of the cleaning solution and this may damage skin and other materials being cleaned.

Non-precipitating water softeners use complex phosphates to sequester calcium and magnesium ions. There is no precipitate to form deposits and alkalinity is not increased. If used in enough quantity, non precipitating water softeners will help dissolve soap curd for a period of time.

Mechanical water softening units can be permanently installed into the plumbing system to continually remove calcium and magnesium. Water softeners operate on the ion exchange process. In this process, water passes through a media bed, usually sulfonated polystyrene beads. The beads are supersaturated with sodium. The ion exchange process takes place as hard water passes through the softening material. The hard minerals attach themselves to the resin beads while sodium on the resin beads is released simultaneously into the water. When the resin becomes saturated with calcium and magnesium, it must be recharged. The recharging is done by passing a salt (brine) solution through the resin. The sodium replaces the calcium and magnesium which are discharged in the waste water. Hard water treated with an ion exchange water softener has sodium added. According to the Water Quality Association (WQA), the ion exchange softening process adds sodium at the rate of about 8mg/litre for each grain of hardness removed per gallon of water. For example, if the water has a hardness of about 10 grains per gallon, it will contain about 80mg/litre of sodium after being softened in an ion exchange water softener if all hardness minerals are removed. Because of the sodium content of softened water, their physician may advise some individuals, not to install water softeners, to soften only hot water or to bypass the water softener with a cold water line to provide unsoftened water for drinking and cooking; usually to a separate tap at the kitchen sink.

Softened water is not recommended for watering plants, lawns and gardens due to its sodium content.

Although not commonly used, potassium chloride can be used to create the salt brine. In that case potassium rather than sodium is exchanged with calcium and magnesium.

Before selecting a mechanical water softener, test water for hardness and ion content. When selecting a water softener, the regeneration control system, the hardness removal capacity and the ion limitations are three important elements to consider. There are three common regeneration control systems. These include a time-clock control (you programme the clock to regenerate on a fixed schedule); water meter control (regenerates after a fixed amount of water has passed through the softener); and hardness sensor control (sensor detects hardness of the water leaving the unit, and signals softener when regeneration is needed).

Hardness removal capacity, between regenerations, will vary with units. Softeners with small capacities must regenerate more often. Your daily softening needs depends on the amount of water used daily in your household and the hardness of your water. To determine your daily hardness removal need, multiply daily household water use (measured in gallons) by the hardness of the water (measured in grains per gallon).

Example: 400 gallons used per day x 15 grains per gallon hardness = 6,000 grains of hardness must be removed daily.

Iron removal limitations will vary with water softener units. If the iron level in your water exceeds the maximum iron removal capacity recommended by the manufacturer of the unit you are considering, iron may foul the softener, eventually causing it to become plugged.

Summary
Hard water is not a health hazard, but dealing with hard water within the home can be a nuisance. The hardness (calcium and magnesium concentration) of water can be approximated with a home-use water testing kit, or can be measured more accurately with a laboratory water test. Water hardness can be managed with packaged water softeners or with an mechanical ion exchange softening unit.

Note: If you are looking for Sodium Free Softeners - you may want to check out the Potassium Based Softeners (K Life).

limescale and its effects on materials...

The build-up of limescale in domestic hot water supplies and primary systems is a major problem that all heating engineers should be aware of. Problems are caused when the scale builds on surfaces such as the inside of the copper tube or the pump, to a point where flow rates drop, valves and pumps jam, or system efficiency decreases.

The following information on available scale inhibiting devices has been complied after talking to a number of manufacturers. The science behind the devices is still under research and the complexity of the physics and chemistry involved mean it is very difficult to ascertain the true effectiveness of such devices without carrying out extensive laboratory testing. Installation conditions and water quality vary so much that it becomes very difficult to draw conclusions from on-site experience. At present, no official standards or methods of testing have been established, so customers often have to rely on supplier guidance.

The build up of scale may also cause corrosion. It is often believed that a lining of scale on the inside of a pipe will protect the pipe. This is not true. The blue colour of the scale is a sure sign of copper corrosion. Scale is a metal salt and is a good conductor of electricity. When it builds up on a metal surface, such as inside the cast iron casing of a pump, it will act as an anode, with the metal becoming a cathode. This anode-cathode set up allows electrons to flow freely between the scale and the metal, allowing corrosion to take place. Also, as the scale is not uniform, the corrosion becomes localised rather than spread evenly over the surface of the metal. In such circumstances, testing the material on the inside of the pump will show the presence of both scale and rust.

The quantity of scale that water can dissolve depends upon temperature, pressure and the pH level. As the temperature of water increases, the volume of scale in solution it holds drops, resulting in the precipitation of scale modules into the water. These molecules join into crystals either on rough surfaces or on other crystals. Likewise, as the ph increases or as pressure decreases (as it does when water is flowing along a pipe or through a control), the volume of scale held in solution drops resulting in scale formation.

It is also worth noting that scale may form in areas where water is turbulent. This is because turbulence causes a drop in pressure, which in turn leads to scale forming.

To prevent scale from being deposited on surfaces, the aim is to create small ’seed’ crystals of scale within the water upon which any remaining scale will grow, forming larger particles of scale suspended in the water. These suspended particles pass along pipework, through any controls, and out through the hot water outlets, without causing problems. Scale particles in suspension will typically grow to 50 microns in size. Particles of 25 microns may be visible to the naked eye. The way to create crystals in the water is to apply an electric field. Individual molecules of scale align themselves with the electric field, and move towards each other (a similar mechanism to the way electrons move along a wire). Once in contact the scale bonds together, forming crystals with the scale atoms in the crystal aligned to the electric field. Crystals will continue to grow in this fashion. In-line magnetic devices rely on a flow of water through a magnetic field to generate the required electrical field. The electric field strength will vary with the flow rate of the water, and will disappear when the water stops flowing. The electric field is only present within the vicinity of the magnets, and once scale crystals have moved past the magnets, they will break down and may build up on surfaces.

Non-intrusive electronic devices produce an electric field (sometimes referred to as a radio signal) along the pipe and within the water. The devices are connected to an electrical supply and do not require a flow of water to set up the electric field. Instead, applying electrical a.c. signal to signal wires or a nonferrous core, creates the electric field. The critical factor that determines the effectiveness of the device is the type of signal applied. Research has shown that a randomly varying ’sinusoidal’ signal gives the best results, although the mechanism is not completely understood. As yet square-wave signal has little effect. The electrical field that is created will travel along pipework and through water, however, the distance will be determined by the position where pipework is earthed. The position where pipework is earthed is important, because electricity runs towards earth, and if such a device is to be fitted to protect specific system components, then preferably, there should be no earth between the device and the components to be protected. One should also avoid fitting these devices on a conducting loop, such as on a loop of copper pipework, as the loop may ’short-circuit’ the electric field, reducing its effectiveness. It is important when buying these devices that the electronics are protected against spikes and other variations in the electrical supply. If not properly protected then the electronics may soon fail. It is also worth checking that the device does not need to be reset if the electrical supply is cut off temporarily.

In-line electrolytic devices are basically self-contained batteries, producing an electric field and current through the water. The electric field creates grains of scale within the water. Again, the electric field is only present within the device, and once scale crystals have moved on they may break down and may build up on surfaces. Like a battery, the device will have a set life span; the longer the life... the lower the effect on scale.