Hard Water

What is hard water?

When water falls as rain, it is "soft" and free of minerals. It picks up minerals as it passes through rock, sand and soil, so most water drawn from an aquifer will be ‘hard’. Hard water is high in mineral salts, especially calcium and magnesium. Hard water, generally, is not harmful to our health and may indeed be beneficial.
Hard water isn't bad water, any more than soft water is 'good' water. For example, many tea and coffee drinkers do not like their drink made with soft water, preferring a degree of hardness. Generally, people used to soft water will find hard water difficult and vice versa.

How hard is Amberley's water?

The New Zealand drinking water standards give a maximum hardness guideline of 200 mg/Litre (The World Health Organisation's maximum is 350 mg/Litre). Amberley's water has reduced in hardness over the past few years from around 150mg/l to just above 100mg/l, which is classified as "moderately hard".

The following chart is an indication of how hardness can be measured.  


Total Hardness



Slightly Hard


Moderately Hard




Very Hard

Above 180

What are the main effects of hard water?

When heated, the minerals in hard water encrust themselves onto items as "scale", affecting the performance of appliances. In hot water cylinders and kettles the scale can, over time, consume more power to heat the water and eventually cause the element to ‘burn out’. Scale deposits are unsightly in bathrooms and kitchens, and they're challenging to remove.

Another effect is that soaps and detergents lather poorly in hard water, so we tend to use more, resulting in a soapy film or scum residue in the bathroom. For some people, this soapy residue can cause skin problems (arising from blocked pores) and hair and scalp issues because shampoo is not washed away completely.

Drinking hard water can reduce your risk of osteoporosis because of the calcium carbonate in the water. For this to be true, however, a good level of vitamin D in the diet is also necessary since it helps the body to absorb calcium. A number of studies have suggested that the minerals in hard water can help prevent heart disease and high blood pressure, as well.

What can I do?

Scale and water stains - the cheapest solution is vinegar.
• Soak the inside of your kettle in vinegar and then rinse well before use. If the build-up is thick, you may need to repeat this several times. Same for your steam iron.
• For taps and shower heads, soak an old cloth in vinegar and then wrap it around the tap/shower head and leave it for two or three hours, then remove and rinse. Repeat if necessary.
• Stains on glassware, tiles, showers: wipe with a vinegar soaked cloth, then rinse.
• Brown staining (caused by Iron) can be removed by using Epsom salts or other readily available products

Soaps and shampoos - if your existing soap or shampoo is not lathering properly, then look for one specially formulated for hard water or use a soap substitute. If you have skin or scalp problems, consult your doctor and let them know that you suspect that it may be related to hard water.

Scale is affecting my hot water element

Research has shown that cylinders are required to be constructed specifically for the type of water they dealing with. In areas of hardness over 100mg/l professional manufacturers recommend [ultra] low watt density elements should be used with a sacrificial anode. The sacrificial anode is designed to sit in the cylinder, attract the minerals and be corroded rather than the element. It is important that how water cylinders are regularly serviced [suggest annually] to check the anode hasn’t corroded away.
Other items that can contribute to element corrosions are;

Water temperature

The higher the temperature the quicker the corrosion. In general, the chemical reactions, double their speed with every 20-degree rise in temperature

Air pockets

Water heater elements must never operate unless immersed in water. An element generates enough heat that it can burn through its copper core in under a minute if the heat does not transfer to water. Air pockets can develop should the hot water system not be bled when filling a tank. 

Power Surge

A sudden voltage increase to the element caused by a power surge can be enough to burn out an element. All heating elements have a voltage rating. Voltages above this rating will burn out the element. Ensure the circuit breaker(s) (fuses) are correctly rated and functioning correctly


Heavy gauge wires feed electricity to the elements. A poor connection or a wire that has slipped off a terminal can cause an element to stop working. These conditions also pose a safety problem because they could lead to arcing or grounding through metal on the tank.


These devices have a high limit switch that shuts off power to the elements when temperatures exceed normal. If they are not working properly they can increase water temperature expediting the corrosion process

Dip tube

The role of the dip tube is to direct incoming cold replacement water to the bottom of the tank for heating. If the dip tube is faulty, the cold incoming water mixes with the hot water at the top of the tank and could overwork the element