Dishwashers


Dishwashers are perhaps one of the most important labour saving devices in the kitchen.

Most people would give up many other things in their home before they'd give up their dishwasher -- some days, they say, they'd offer up their kids first, and then throw the dog in for free.

Many people, though, are still anti-dishwasher. Some people say there's really not much labour being saved, given the time needed to load and unload the dishwasher. They say they can whip through dishes for two for breakfast or lunch in 5 minutes, 10 minutes for dinner dishes. What they omit from their calculations, though, is the time required to load the dishpan or sink, let many things soak (while the water in the sink is getting cold,) and the times they need to empty the dishpan and start the next batch with clean water.

Some people say they don't need a dishwasher because they clean up as they go along, though not many really actually do. They may not realize that washing by hand as you go along actually uses more water than running a dishwasher. The US Department of Energy says that if you run a dishwasher when full, it uses 6 gallons (23 litres) less of water than if you do the same dishes by hand -- and that's 6 gallons less of water that you have pay to heat, to boot. Dishwashers made after 1994 are likely to be even far more energy efficient than their predecessors.

A few people use paper plates to avoid saving on dishwashing, though even they would agree that washing a plate is more environmentally friendly. Finally, you have some who say that dishwashers release too much steam into the house, especially during already-humid summer days.

It appears to be true, though, that if you have a dishwasher, you are more likely to actually cook more often. Some say that dishwashers are the best kitchen tool for those who prefer cooking to cleaning -- and who doesn't? Still, even dishwasher fans will admit that while chucking dirty dishes in is the fun part, emptying the machine afterward can be a drag.

Market

Dishwashers are really only common in Canada, the United States and in Western Europe, particularly northern countries with the exception of the UK. Even in high tech countries like Japan and South Korea, dishwashers have not been adapted. Kitchen space may be a consideration. In other countries, if a household is rich enough to afford a dishwasher, it means they can afford household help and the householders then have the help do the dishes. Immigrants from these countries to the west are slow to adapt to using dishwashers, even if they have bought into all the other kitchen appliances. Some immigrants feel guilty about turning it on, because of the myth of it costing more to run it than by doing dishes by hand. If they buy a house that has a dishwasher in it, they may use it to store food or dishes in instead.

In Europe, the four major manufacturers are in order of importance: Bosch-Siemens-Hausgeräte (BSH), Electrolux, Whirlpool and Miele. Dishwasher production in Europe is centred in Germany and Italy. Bosch's sold in North America may be European design, but they are made in North Carolina.

Up until about the 1980s in America, most dishwashers sold went into new homes. Since then, in America, most have been sold to replace existing dishwashers (the US Department of Energy says to expect a dishwasher to last for an average of 10 years.) In Europe, most sales are still homes acquiring a dishwasher for the first time. Some more expensive new homes in America are now having two dishwashers installed. A second or third one might be a drawer unit (such as that made by Fischer and Paykel of New Zealand) for small loads. Many Orthodox Jewish households may also have two dishwashers -- one for dairy, one for meat.


Country197919811986199119931997199820032005
America43%54 to 60%
Austria37%48%48%
Canada26%38%54%59%55% (sic)
France34%40%40%
Germany36%47%49%60%
Italy22%28%27% (sic)
Netherlands17%24%30%
Spain19%20%
Sweden41%50%51%
UK4%14%16%20%21 to 24%%28%
Switzerland48%54%60%
Turkey8%

The above table was compiled from various sources. Thus, estimates for some years vary by source. Sources are indicated in Acknowledgements below.

In Canada in 2003, 62% of households in British Columbia had dishwashers, 57% of households in the Prairie provinces, and 55% of households in Ontario. The overall average penetration rate in Canada was 55%.

Models

Freestanding (aka portable) dishwashers used to be the cheapest, but now are more expensive than built-ins. They have casters on them so that they can be moved about in the kitchen easily. Most of them have cutting boards on top and can be a handy source of extra work surface in the kitchen.

A built-in dishwasher requires an electrical line, a hot water line, and a drainage pipe that taps into the kitchen water drain. The control panel for a built-in one can be on the front of the door at the top, or right inside the very top of the door, so that you can't see it when the door is closed.

Half-sized, compact thin dishwashers will be about 18 inches (45 cm) wide. They really won't any handle anything but table dishes -- you'll need to do pots by hand. They can cost as much as the full-sized ones do.

Stainless steel interiors are very expensive. Some say the stainless steel tubs hold the heat better, helping the dishes to dry better afterwards. Others say that what's more important is the insulation surrounding the tub, and that the gauge of the stainless steel used for the tubs won't be thick enough anyway to really have any impact on its heat retention. Plastic ones are cheaper, but over time the plastic can absorb grease and soap. Some prefer plastic insides, though, saying they are less likely to develop leaks over time, as the stainless steel ones which are welded together can. Almost all European dishwashers have stainless-steel interiors, Plastic interiors appeared in the mid 1970s.

You can also get counter-top dishwashers that will do a few place settings at a time.

A few models, such as Electrolux's VISI, have windows in the front door now.

New dishwashers come with motherboards in them -- so you can be sure they're not going to last anywhere near as long as the previous generation of dishwashers did.

Drawer Dishwashers

These will be built into kitchen cabinetry. They come in single units. You can buy one, or as many as you like. If you buy two, you can mount them on top each other, or at completely different places in the kitchen. You can get an integrated two-drawer model. If you do both drawers are the same height. In any of these scenarios, each drawer is independent of the other.

Some people get one or two of the drawer dishwashers to use for small loads, and then a full-sized dishwasher as well. The drawers use less water and energy than full-sized dishwashers, so you can run a load right away without waiting for a full-size dishwasher to fill up. Each drawer uses only about 2 1/2 gallons (10 litres) of water for its entire cycle.

Drawer Dishwashers seem to be able to hold things up to 11 1/2 inches tall. You load them through the top. They have a drying fan, but no heater for a hot air dry cycle. When a wash cycle is done, you pull the drawer open and leave it open for the dishes to air dry.

They are being made (as of 2007) by manufacturers such as Fisher & Paykel of New Zealand, and KitchenAid.

In-Sink Dishwashers

Picture a standard kitchen double-sink made of metal. An in-sink dishwasher is one-half of that double-sink. Picture that half as having a ridged steel lid on it. If you lift up that lid, in it you see the dishwashing basket and the spraying arm. If you lift out the basket and the spray arm, you can use the sink as a sink. The dishwasher can only do about 5 plates plus a few other items at the same time. It does it, however, in half the time of a full-size dishwasher, and is very, very quiet. It is right at counter level, so no bending is required to access it. There is no built in heater to dry the dishes, but the lid pops open at the end of cycle to allow the dishes to air dry.

Commercial Dishwashers

Some professional level dishwashers (such as Champion) can do a load in 5 minutes. But they cost around $3,000 US (2001 prices.) Hobart commercial ones will do a rinse around 200 F (93 C), and a whole load in 90 seconds.

Some models are designed to work off commercial water tanks that store the water around 200 F (93 C.) Many, though, have booster heaters, that require a 220 volt electricity line to power them.

Most commercial ones, despite their rinse cycle, require a pre-rinsing of dishes. And they won't do well with dried-on food, as a cycle time of 3 to 5 minutes or less isn't enough softening time. Basically, the dishes have to go in pretty "clean" in order to come out clean. Consequently, some say they are really more dish sanitizers than dish cleaners.

They have no drying cycle. You just remove the rack of dishes and let them air dry, or leave the door open. The dishes will air dry very quickly because they come out so hot.

Most commercial dishwashers have removable racks -- you stack the dishes in a rack, and then place it in the dishwater. Most commercial kitchens have several racks, as only one can go in at a time, and generally you want to be able to put one through while a previous load that has just been taken out is set somewhere in its rack to air dry. These racks require storage space, as they can be quite bulky.

In these commercial ones, often the rinse water from the last cycle is used as the wash water for the next cycle. They will either have a pump that automatically feeds detergent in, or have you toss some detergent in manually as you would with a home-use one. They have filters that need cleaning.

You can also get undercounter commercial dishwashers that are like home market dishwashers, but with the sanitizing power of commercial ones. Commercially, they're aimed at low-volume places such as churches, community centres, day-care centres, etc. They will still have the heat-boosters in them. Though small, they can still process up to 30 racks of dishes an hour with 2 minute cycles. You have to put the racks in: generally they are about 19 to 20 inches (48 to 50 cm) square. The machine inside is just an "empty box", making height spacing very flexible. Inside the machine, you get to use 1 rack, 2 racks at once, stack them, etc. You still need somewhere to put the racks of dishes to dry as they come out, and, as for the full-size commercial dishwashers, the dishes still basically have to go in very well rinsed to start. They are quite loud and generally have no timers on them.

Features



Dishwasher Racks

If you have very large dinner plates, china chargers or tall pots that you would like to put through your dishwasher, having the option to adjust the shelf height can be useful. Not all models have this: on those that do, it's the top rack that adjusts up and down. On others, you have to remove the top rack entirely to fit tall items into the bottom rack.

Some have some clips on their racks, to hold lightweight items in place so that they don't flip over and fill up with water, or end up at the very bottom of the dishwasher. The clips also hold crystal stemware safely in place, so that it doesn't rock and chip. Some racks have rows of prongs that can fold down when needed to accommodate larger items.

The top rack is usually for glasses, the bottom for plates.

If the top rack has a sprayer of its own, you don't need to worry about things in the bottom rack blocking water from reaching the top rack. Only very few machines just have the water coming from the bottom. Some have a spout column that rises from the bottom to do mid-level spraying as well. Some higher end dishwasher models have cycle choices that only do the top rack.

Some cutlery baskets have slotted lids in them, to keep cutlery items apart so they will clean better; this also keeps small items in the baskets.

Sound

The noise that a dishwasher makes during operation varies greatly by model.

It is hard to know what a machine is going to sound like until you've paid for it, got it home, installed it and run a load through it, at which point it's too late to do anything about it -- it is well and truly yours. Basically, you have to go for those that advertise themselves as "quiet operation", and hope for the best. Price is an indicator, though: the quieter the machine, the more expensive it will be. And in general, newer model machines are far quieter than the older model ones were.

Having a quiet dishwasher is important if you live in a small space, an open-floor plan house or loft, or just want to run it at night. A few models are so quiet that you literally have to put your ear against the door to hear if they are running.

On quieter machines, the motors and pump are mounted to the base-pan. On nosier ones, they are mounted to the tub, which amplifies the sound. How quiet a machine is will also depend on the insulation material used. The food grinders present in many North American models can add to the noise level as well.


Other Miscellaneous Features
    • Child Lock: prevents anyone, not just children, from monkeying with the settings on a dishwasher and changing them from the way you like them;
    • Delayed Start: a timer lets you load the dishwasher and then have it come on in the night, if you wish, when water or electricity rates may be lower in your area;
    • Plate warming: some machines have a feature whereby without running water they will warm plates. This is handy, provided that your dishwasher isn't already filled with all the prep dishes;
    • Pots & Pans cycle: this is good for really dirty dishes, or caked on or baked on food. Some people feel though that many of the European design dishwashers aren't built with the flexibility to handle the kinds of big, honking cooking pots and dishes that North Americans often use;
    • Rinse & Hold Cycle: Meant to be useful for those who fill a large dishwasher over a period of a few days. This just runs a rinse on dishes that you have put in there, in order to prevent food drying on them, or to prevent smell, then empties the water out and leaves the dishes there without cleaning them. The US Department of Energy advises against using this option; they consider it wasteful.

How dishwashers work

Dishwashers don't pump in water to fill themselves. They open a valve that lets in water, driven by the pressure in the household pipes. The pump in a dishwasher is just used for draining.

A normal wash cycle is "wash, wash, rinse." The first wash is actually a "pre-wash", meant to rinse away debris, and soften the rest up. This is why you just don't need to rinse dishes anymore before putting them in the dishwasher. It's a waste of time and water to do so. It's only with older dishwashers that you had to rinse stuff before you put it in, but many people still do out of superstition or habit. It's this manual rinsing habit that causes the dishwasher-phobic crowd to say to them, if you're going to use all that water and time rinsing them, why not just finish washing them while you're at it -- and who can say they're wrong?

Most dishwashers fill up with water based on a timer, i.e. how long they allow for filling, rather than actually measuring how much water they have taken in. This can be a problem in areas of low water pressure. Consequently, most dishwasher manuals will give an acceptable hi and low water pressure range for that model.

When buying a dishwasher, you'll want to check how many gallons / litres of water are required per wash.

A dishwasher will have either have an internal food grinder to grind up food particles before flushing them away, or a food screen (aka filter.) North American ones tend to have the grinders (some even have built-in garbage disposals!) European ones tend to have the filters instead, which have to be cleared from time to time. Some of these filters are self-cleaning, but not all, and some of them can be a lot of work to get at, and then a real pain to remove. If you are considering a model with a food filter, check to see how easy it will be to clean it.

Dishwashers turn themselves off when they are done. Some have a built-in indicator in the door to tell you the load inside is cleaned.

Hot Water

Water needs to be very hot to avoid greasy films and soapy residues -- at least 130 F (54 C.)

North American units rely on the water from the tap being hot enough -- because North Americans keep huge tanks of simmering hot water in their houses at all times. For drying, they have a heating element at the bottom. European dishwashers heat their own water; some newer North American ones have a water heating option as well.

Even machines that heat their own water, though, come with advice to run the hot water at your sink for a minute or so to bring the water in the pipes up to temperature, whether you are running a built-in dishwasher or a free-standing one that hooks directly up to the sink. This is particularly important if your dishwasher doesn't have a heating cycle to prevent part of the water that it fills up with being colder.

It is usually recommended to have the water in a dishwasher between 140 and 160 F (60 to 71 C.) Dishwashers with their own water heater and temperature control may offer a "sani-cycle" that usually gets the water to 180F (82 C.) This is the minimum recommended temperature for sanitizing items. The sanitizing aspect is especially nice to have for things that have touched raw meat. Many North American dishwashers that have the bottom heat-dry coil have it come on during the final rinse, to super-boost the temperature of the water for that rinse.

Hard Water

Hard water will cause clouding on glass put through a dishwasher. Some people with hard water find that every once in a while, they need to do their glasses by hand to get them clean. Many European dishwashers use salt as a water softener. Dishwashers in the UK have a salt cup too that you fill for each load to soften the water.

What Can Go In

For many people, their philosophy is "if it isn't dishwasher-safe, they don't want it."

Many things you'll buy are "upper rack washable," meaning they have to be kept away from the heating element at the bottom in North American dishwashers.

If your heating element is concealed, then anything that is "top rack only" can in theory go on the bottom rack. It's during the heating cycle when the exposed element in the bottom comes on that plastic things are damaged. Dishwashers with enclosed heating elements are considered better.

Whenever the topic of knives comes up, someone will always add "don't put them in dishwashers." Often they can't say why. This probably dates back to earlier times, when knives were carbon steel and were being washed in restaurant dishwashers at much higher temperatures. Now that knives are stainless, this concern for the metal itself is outdated. Some point to wooden handles on knives as a reason not to put them through -- but some say if you don't mind getting the handles bleached, then not to worry. Others say that you shouldn't put knives in because their banging against other things can dull their edges, and that repeated trips through a dishwasher may mean that you have to sharpen your knives more frequently. But most people do whack their knives through, placing them off to the side out of the way of other moving objects, and they seem to survive just fine.

Wooden cutting boards will fall apart over time if put in a dishwasher, but overtime means about five years. If you buy your wooden boards cheaply enough, it may be worth it to know that you are using sanitized boards.

You can put sterling silver and silver-plate cutlery in, as long as no other metal touches it. The reaction that occurs when stainless steel touches silver in the right environment is called a "galvanic couple." It causes a corrosive cell, which blackens the silver.

Silver put through a dishwasher can come out with a dull coppery or yellowish colour to it. It's caused by a film left by the detergent that is then baked on during a heat drying cycle. Remove the silver right after the wash cycle, and dry it by hand before the heat-dry cycle -- that will remove the film, and stop it from building up. The yellowing can also be a sign that you are using too much dishwasher soap, and often just cutting back on that can solve the problem.

Brand new sterling silver is prone to get coppery-coloured spots on it. Even sterling silver has a small amount of copper in its mix. A reaction can occur between drops of water, and copper that happens to be in the surface of the sterling cutlery. After a few washings and reactions, the copper in the surface will be mostly gone. Or, you can avoid it entirely by removing the silver before the heat cycle and drying by hand.

Silver items with bone, ivory or mother-of-pearl pieces in them continue to be hand-wash items.

Living with a Dishwasher

A dishwasher is a great place in which to stack dirty dishes. It frees up counter space right away, especially important when you are cooking.

Single people can stack it over the course of several days, and then run it only when full. To do this, though, you need to have enough of various kitchen utensils (pots, bowls, cutlery, plates, glasses) to get you through.

A dishwasher can clean many things other than just kitchen items: detached glass chandelier baubles, light fixture globes, plastic blinds, various plastic items from around the house. You can try many things around the house going through; every once in a while, you'll guess wrong (hint: while it might seem like a flash of inspiration to clean metal blinds by putting them through the dishwasher, most will come out with the metal blotched.) But you can put pet bowls, kitchen dish brushes, sponges and your dishcloths through to sanitize them. A run through really takes the smell out of vinyl and plastic cutting boards.

Put no cast iron or aluminum through.

Generally, most people advise to use the air dry (aka "condensation drying") instead of the heat cycle for drying. The heat dry cycle uses up the lion's share of the energy required to run a dishwasher, so air drying is far cheaper. Air drying is also safest for plastic items. For air dry, as soon as the dishwasher has finished, open the door for a few seconds to let the steam moisture out, then close the door again, and letting the dishes dry from the residual heat. Letting the steam out helps dishes dry better because it prevents a lot of condensation.

No matter which cycle you choose to dry the dishes on, sometimes there will still be some water in the rims on the bottoms of cups or bowls; just have a tea-towel at the ready.

A dishwasher can take 1 to 2 hours to do a load of dishes, depending on the model and cycle you choose. It seems to take 10 hours when you're in a rush, desperate for it to finish so you can force-feed the next load through. At times like this, you may wish to consider using the heat cycle to speed up the drying.

Running a dishwasher overnight can be useful if yours is quiet enough, because then you have clean dishes when you wake up in the morning (and you may save money on the electricity rates in your area.) It's particularly good if you use the air dry cycle -- it gives the dishes lots of additional time to drip dry overnight.

It can be a bit of a puzzle about what to do when the top rack is full, and the bottom is empty, but you want to run the machine. Look for things in the house that can use freshening up -- odds & ends in the kitchen that are dishwasher safe, stuff on shelves that hasn't been used in quite some time.

When putting knives in a cutlery basket, put them pointy side down always for safety reasons.

A build-up of iron, lime scale, grease and soap scum can affect performance of the machine. Some people advise to run the machine every two months completely empty, with a quart of plain white vinegar in it, and no detergent.

Always make sure to run the dishwasher, and empty it, before a dinner party -- never let a dinner party start with your dishwasher full of your dirty prep dishes -- you'll need the space!

Cleaning Challenges with Dishwashers

Most cleaning problems come from bad judgement calls when loading the dishwasher. Loading it is an art. Oftentimes, if a load doesn't come out clean, it's because of how you packed the dishwasher -- you may have blocked the streams of water that do the work. (Othertimes it's because the soap dispenser didn't open, or you just plain forgot to put soap in.)

Stuff that sticks well to dishes can be hard to get off in a dishwasher -- stuff like peanut butter, cream cheese or stuck-on egg yolk. The "simmer lines" in pots, marking the surface edge of a liquid that you've simmered in a pot for a long time, can also be a challenge for a dishwasher. Seeds (such as those from breakfast cereals) and grains such as rice left in / on dishes can be problematic.

Soaking dishes before putting them in the dishwasher is only necessary if you have baked-on or dried-on food. If something is burned on a pot, you will definitely have to soak and scrub it first before putting it through -- at which point, you might as well finish the job in the sink.

Detergents for Dishwashers

Hard water reduces the ability of the soap to do its work. Most North American dishwashers have two detergent cups, one for pre-wash and one for wash. To compensate for hard water, fill both detergent cups, plus use a rinse aid. With detergent tablets, though, you only have the detergent in the main wash.

Most people use too much detergent in their dishwashers. If you are using powder, you may not need to fill up the cup entirely. Some people find that 1 to 2 tablespoons of powder, depending on how soiled the load is, often does the job fine. Some people say that if you use too much powder, and don't use hot enough water, that it won't all dissolve, and will build-up in your household pipes.

Some repair people recommend gel, some recommend powder, some tablets. There's no firm consensus. Some older dishwashers can have a problem dissolving powder and tablets well.

Some people break the powder tablets in half for lighter loads. 1 crushed tablet = approx 2 tablespoons of powder.

Dishwasher powder is good for ever. If it does clump, because it's picked up moisture from the air, put it in an air-tight container, store it away from the sink, and just crumble up the clumps with your hand as needed.

Many detergents give off a strong "chlorine" smell which some people find disagreeable. You can now buy chlorine-free ones. On the other hand, many people recommend not using lemon-scented detergents owing to the "acids" in them (unspecified acids, and perhaps this is too widely quoted, too easily, for one not to be suspicious of this "fact.")

Never use regular dish soap in your dishwasher. You will end up with an "I Love Lucy" scene in your kitchen. Dishwasher soap is designed not to produce bubbles.

Many people swear by dishwasher soap for soaking things in to lift off burnt-on bits of food.

Gels often have a chlorine bleach in them, which some say can shorten the life span of rubber seals in the dishwasher. Some find that gels can leave a cloudy film on glassware, and don't always work well in hard water. Gel also comes in tablets.

Rinse aid makes the water "wetter", letting it drip more easily off dishes, and thus help avoid spotting. Spotting can also be caused by hard water deposits. Rinse aids can be liquid or solid.

History Notes

The first successful design for a dishwasher was patented in America in 1886 by Josephine Garis Cochrane. See the full biographical entry on her.


The company she founded, making dishwashers for restaurants and institutions, was sold to the Hobart company in 1926. Hobart at the time made a few home electrical goods such as stand mixers under the brand name of "KitchenAid". By 1940, Hobart had been acquired by Whirlpool. Its dishwashers by this time had acquired built-in heaters for drying the dishes.

In 1949, Hobart began selling dishwashers for home use under its KitchenAid name. They really only started to crack the home market as the 1950s went on. Post-war prosperity in America put them within reach of the better-off middle classes, just as leisure time for these women started to become more important. They wanted time out of the kitchen for other activities. Dishwashers could also be pitched to husbands on the basis of hygiene. They could "sterilize" things (at least in marketers' terms), because they could use water much hotter than you would be able to manage doing dishes by hand.

Built-in dishwashers appeared on the market in 1969. Quiet dishwashers came on the market in 1985.

Dishwashers used to be top loading.

Acknowlegements