Detergent is split between two categories, with two options within each. Fist the form it comes in,

1. Tablet form

2. Powder form

Then there is the chemical composition of the detergent, which, due to environmental concerns within the wider society, is split between two camps,

1. Biodegradable

2. Non-Biodegradable

Obviously the first category is self explanatory, but the second category is less clear. What separates biodegradable and non-biodegradable detergent is most usually phosphates. Phosphates are used by detergents to combat hard water. Hard water can be found in most midland and southern areas of England.

Hard water contains Magnesium and Calcium ions which produce scaling. Phosphates aim to soften the water by lowering the mineral content of it. But, the problem with phosphates is they do not naturally biodegrade and therefore are a problem for the environment.

The actual cleaning composites of the detergents is a mix of either chlorine or oxygen bleaching agents, enzymes, starch, anti cake and foam agents and gels. These composites help to break down the food deposits and then to bleach them.

Soft and Hard Water: It’s Implications for a Dishwasher

So you may be asking yourself what is soft and hard water, and how does this effect me and my dishwasher? Well, hard water is rich is minerals, primarily two minerals,

1. Calcium Ca2+

2. Magnesium Mg2+

To a lesser extent some hard water locations may have a small to medium amount of Aluminium, Iron and Manganese.

Now, these minerals have their advantages for practices such as brewing beer. But, when it comes to the internal parts of a dishwasher they prove problematic. The minerals attach themselves to heating elements within the dishwasher, which is known as scaling or limescale. Over time this will negatively effect the performance of a dishwasher and may destroy some elements.

Most dishwashers have a solution to this problem. They have a salt dispenser, which adds a small amount of salt to the water, which in turn helps to soften the water and lowers the risk of scaling.

A survery of England and Wales has concluded that the majority of England is a hard water location. Wales on the other hand is mostly a soft to medium location. There are some exceptions in England, such as the North West and North East and Cornwall, which is soft to medium. But, virtually the whole of the Midlands and South of England is hard water.

Tips: How Best to Use a Dishwasher

Below is a list of things to do and avoid when operating a dishwasher.

1. Do not wash crystal, gold plated china, pans made from cast iron, silver plated china, copper, kitchen utensils without a steel handle such as wood or plastic. Any of these products may be faded or break from continual dishwasher washes.

2. When unloading a dishwasher it is advisable to unload the bottom draw first. Most dishwashers do not dry out all of the water. So, when cups are removed from the top draw first, they may drop water onto the bottom plates and utensils.

3. Some dishwashers contain a filter which needs maintenance. You should periodically check to clear any residual waste or limescale from the filter.

4. Some dishwashers require salt and rinse aid alongside the detergent to perform at their maximum. The salt helps to soften the water and the rinse aid contains surfactants to stop droplets of water forming and smearing glassware and plates. Dishwasher salt is not the same as culinary salt, and is purged of impurities, manganese and iron. Inserting salt which is not designed for a dishwasher will more than likely damage the softening system.

5. Over or under filling a dishwasher has it’s disadvantages. When too many items are placed inside, then the dishwasher will have difficulty cleaning to it’s peak performance. Cups and plates may also knock against each other and become chipped. While under filling a dishwasher does not have any disadvantage to the cleaning performance, there will be a waste of detergent, water and electricity.

6. Check that the dishwasher sprayer and sprayer arm have a free motion to clean the whole of the load

Features of Dishwashers

When it comes to features, wash programmes are a primary consideration. The more the better. Some of the key programmes are as follows,

1. Fast cycle, plates with little dirt on them.

2. Economic, low temp, saves on electricity.

3. Performance, high temp, intensive wash for caked on dishes.

4. Half load, for fewer dishes, less litres of water are used.

5.Glass wash, calmer water pressure to protect delicate and expensive glass.

Hardware features are few and far between. An LCD display is standard on virtually all dishwashers. And a clear and easily understood panel is desirable. Apart from this, internal adjustable racks and baskets are another option to look for.

When it comes to cosmetics, dishwashers are usually rather bland in design and coloured in white, gray or silver. For the style conscious, built in dishwashers are either hidden behind a kitchen cabinet, or the door of the dishwasher is attached with a cabinet facade. However, it has to be said, Smeg have recently produced a range of 1950’s styled dishwashers in a selection of extravagant colours.

Sound dampening has recently improved for high end dishwashers. While an entry level machine will produce a decibel level of around seventy, a high end machine will only produce a decibel level of forty. Which is similar to the sound a kettle makes.

The internal basin of dishwashers is either made from plastic of stainless steal. Stainless steal basins last longer and are to be found in all high end machines. A filter is installed in most basins, which will need to be cleaned manually on low level machines, but, automatically cleaning filters are available. A basin will typically include two draws for inserting plates, utensils and cups. The more you pay for a dishwasher, the more likely the draw can be collapsed, removed, and folded, to increase greater flexibility.

On expensive dishwashers, features such as a delayed start time are included. Microprocessors and sensors have enabled dishwashers to alter the length of wash cycles by sensoring water temperatures. This is useful for people who do not wash on full loads, due to the resources saved.

For medium level machines, an LCD display to operate the wash programmes and to show the status of the current wash cycle comes as a standard. The dishwasher door should also self balance when attempting to load and unload pots and pans. A cutlery basket and adjustable internal baskets are to be found in virtually all dishwashers.

So to conclude, an LCD display, a self balancing door, baskets and plenty of wash programmes are about the pinnacle of features to be found on an average dishwasher.

Performance of Dishwashers: Cleaning, Drying, Energy

When it comes to performance, dishwashers are graded on three important performance criteria. The grading system goes from A down to G. With grade A being the best. The three performance categories are as follows,

  1. Cleaning performance. Indicates how well the machine can remove dirt and grease.
  2. Drying performance. Measures the amount of excess water at the end of a wash cycle.
  3. Energy efficiency. A high performer can save a substantial amount of water and electricity.

The cleaning performance of a dishwasher is not only a visible indicator. There is also hygiene to consider. Manufacturers claim that dishwashers kill more germs than washing at a kitchen sink.

A dishwasher will operate at temperatures of around seventy celcius. Which is higher than hand washing. This means that dishwashers wash close to or exactly at sterile levels.

A dishwasher can also save time. Research has shown that a dishwasher can save a couple of days in saved time, in comparison to washing dishes by hand, over a year long period

The green credentials of dishwashers are clear cut. An average wash cycle at a kitchen sink (for a family) uses around fifty litres of water. Whereas a full dishwasher wash cycle uses around twenty five litres of water on average. This can add up to a considerable amount of water per year.

Sound damping is a final performance consideration. Manufacturers have done a good job of developing superior sound absorbing machines. You should expect a decibel level of around 42. Older machines are around 55-70 decibels. A difference in 10 decibels, which is three to five times quieter.

Capacity of Dishwashers

The capacity of a dishwasher corresponds to the amount of plates and utensils which can fit into it per wash cycle. The exact terminology used by the industry is ‘place settings’.

And it’s an international standard followed by most countries. One ‘place setting’ refers to the number of items used in one meal by one person.

a look inside what it can hold

One place setting

  1. One plate.
  2. One soup bowl
  3. One desert bowl.
  4. One tea cup.
  5. One tea cup saucer.
  6. One fork.
  7. One Knife.
  8. One desert spoon.
  9. One tea cup spoon.

The size of the above items is not specified in the ‘place setting’ standard. Only, that one of the above, of an average size, can be held by the dishwasher.

Therefore, the ‘place setting’ standard is not an exact science, but a general guideline. Dishwashers typically have between four and fourteen place settings.

The average is around eight, but it’s recommended (space permitting) to have in the region of twelve place settings for your new dishwasher.

A History of the Dishwasher

A dishwasher is an appliance/person used for washing plates, dishes, forks, spoons and other utensils. A dishwasher generally refers to two things, a person washing pots and pans by hand, or a mechanical appliance which does part or all of the washing by itself.

old dishwasher

The modern day mechanical appliance runs on electricity, and apart from needing to be loaded, does all the washing by itself. The use of mechanical dishwashers in developed countries is widespread, with the vast majority of residential homes and commercial eateries using them.

Mechanical dishwashing machines were invented much earlier than their electrical counterparts. Reports suggest the first patent for a mechanical dishwasher was issued around one hundred and sixty years ago. But the current dishwasher owes it’s genesis to an invention of Josephine Cochrane.

Her hand operated dishwasher was unveiled in 1886 at the World’s Fair, which happened to be hosted in the USA, in the city of Chicago. Josephine was a wealthy lady with plenty of servants, and it’s claimed that her motive for inventing her machine was to stop her servants damaging her fine china.

The first dishwasher which incorporated plumbing was developed in the roaring twenties. Invented by W H Livens, it was a front loading machine, commercially a success and continued to evolve until electrical components and elements were installed. The 1970’s was the decade when dishwasher became a common appliance in most western households.

The modern day dishwasher works with a simple to complex timing mechanism, which can be operated through either mechanical or electronic buttons. A dishwasher takes water from the home’s water supply through an intake valve. A pump connected to an electric motor then forces the water to a spray arm. The spray arm is located at the top of the internal basin, and sprays water and detergent onto the plates etc.

Electricity Consumption of Dishwashers

An energy efficient dishwasher has a two fold approach, not only is water saved but also electricity. On average, a grade A dishwasher will use 1.06 kWh per wash cycle.

electricity outlet

The cycle used for testing is usually the ‘economic’ programme, even though this is suitable for most normal loads, it should not be used in every case.

Per year a grade A dishwasher (EU class) should consume 312 kWh of electricity per year. That is the projected figure for 2010. In 2008 the figure was 318 kWh per year.

Therefore, dishwashers have become 6 kWh of electricity more efficient over a two year period.

Below, electricity consumed (per wash) by grade,

Grade A – 1.06 kWh
Grade B – 1.25 kWh
Grade C – 1.45 kWh
Grade D – 1.65 kWh
Grade E – 1.85 kWh

One factor which is not highlighted by most manufacturers, and not noted by the energy labels, is the amount of electricity consumed when a dishwasher is on standby.

Water Consumption of Dishwashers

Water consumption is especially important if you’re on a water meter. The first modern day dishwashers consumed around fifty to seventy litres of water per wash programme.

This was similar to hand washing. However, a modern day dishwasher should now use less water than washing in the sink. Below, a current water consumption level by graded dishwashers.

Grade A – 15 litres
Hand wash – between 40 and 150 litres

Comparing an average dishwasher from five years ago, to one in 2009, an annual saving of 1500 litres is possible. This could be even higher against hand washing. Whilst hand washing can be very efficient if your careful, reports tend to suggest, on average, around fifty litres will be used per wash.

Choosing the correct wash programme is important for saving water. For plates which are only slightly dirty, a low temperature setting is required. Wiping off any excess residue (from plates, pans etc.) can also help.

But ,most modern dishwashers can handle scraps of food. Only using your dishwasher when it is full is another way of helping to save water.