You can’t save water using only your dishwasher. To do that you would need to adjust the washing-cycle settings, and then check how much water you’re using. But if you don’t know what settings to change, or how to monitor your water usage, it’s difficult to find out.

This is where a simple tip comes in. All it requires is a little arithmetic: knowing how much water makes one cup of dishes and how many cups there are in an average dishwasher load. You can use this information to calculate the overall savings you can expect from adjusting your dishwashing cycle.

There are some caveats: the ratio of glasses to plates isn’t quite right; and you’d have to make sure that no dishes were rinsed twice, which is possible with the uppermost load setting. But together these factors make up less than 1% of the total energy cost for making one cup of dishes.

You probably think that your dishwasher uses a lot of water. It’s true that it uses a lot of water to wash dishes. But it doesn’t use very much water overall, especially if you put in the right kind of plates and glasses, and run it with the “short” cycle (allowing for an extra rinse cycle after the dishes have been put away).

If you have a dishwasher, you might want to do this: start with the dishes still soaking in the sink. Put them into the dishwasher as soon as they are dry, and run the short cycle. Then take them out again, put them back into the sink, and run a normal cycle; that takes care of any last bits of soap.

On average this saves about eight gallons of water for every load.

If you want to be slim and green, you have to give up one of those. It’s not enough to just be interested in the environment; you also have to adjust your lifestyle. A dishwasher is one of the biggest consumers of water in an average home, so it can’t be that hard to make it more efficient.

The standard advice for making a dishwasher more efficient is to run it with a half-load. This cuts water use by 2/3 and energy use by 1/3, which is good, but not all that much better. The reason is that washing plates, glasses and silverware keeps the current wash active for several minutes, even after the dishes are done; despite the half-load recommendation, people still tend to wash as much as they did before.

In theory a half-load would be perfect. But in practice there is no way to keep dishes from being rinsed during the “dry” cycle, because they fall on the floor anyway. So if you want real efficiency, you have to tell your dishwasher to clean its own dishes at the end of every cycle instead of waiting for them to be dropped on the floor. Fortunately this is very easy: when you put a plate in your dishwasher it should

If you take the time to check your dishwasher load-settings, you will notice that a nominal setting of 1/3 full would lead to the same amount of washing as a setting of 3/4 full. That’s because, at the end of the cycle, each dishwasher has an “air gap” between dirty and clean dishes.

A standard setting is 1/3 full: that way, there will always be enough water to wash the dishes, but not so much that it overflows into the air gap. But if you have a model with an air gap and you want it more efficient, here’s how you make it so:

1. First, check out your model’s manual: some dishwashers have settings in which 2/3 or 3/4 of the dishes are removed before they go into the final rinse. In those models, use those settings instead.

2. Make sure that your dishwasher uses hot water only! At temperatures below 120°F (49°C), dishwashers do not get nearly as much done with cold water; that’s why many dishwashers have special dispensers for hot water.

3. If your dishwasher has a special dispenser for hot water only, install exactly one half cup

The dishwasher is one of the biggest energy hogs in the kitchen.

The limit of a dishwasher’s efficiency is when it reaches a certain level of water saturation. The same principle applies to clothes washers and showers, too. The higher the water pressure, the more efficiently they work. But there is a point where getting more efficient doesn’t help.

The average household has two dishwashers: one that has a five-minute cycle, which may be three minutes short of saturation; and an identical one with a ten-minute cycle, which may be seven minutes short of saturation. The difference between them is somewhere between one and two gallons of water for every wash load.

Why does this matter? Essentially because the other dishwasher uses a lot less water than the first one. If you can cut your five-minute cycle use from five gallons down to two or three, you will save nearly two or three gallons every time you do your dishes.

Think about it: you are trying to wash a large amount of water-intensive crockery and cutlery in a small amount of water. The challenge is to keep the water heating up. Your dishwasher has a powerful heater, which is the source of the heat, but the only way to get that heater to work is to run a full cycle in order to pump out all the water. So how can you reduce your energy use?

The answer is that you should set your dishwasher on an “eco” mode. The great thing about these settings is that they are simple: no pre-rinsing, no rinsing, no drying at all. Eco modes use far less water than normal cycles, but more than half their weight comes from electricity; so the dishwasher pumps out less water and uses less power than normal.

It’s not quite so simple with pots and pans (and knives and spoons), which often need re-washing after each use. But it’s much easier with glasses because glasses don’t break or scratch as easily as crockery does.

A good dishwasher has a perfectly reasonable cycle. But it doesn’t use all the water, because the soil in your pots, pans, or other dishes is mostly water. The best dishwashers let you adjust the time the water stays in contact with each item on the dishwasher rack, so you can choose from short, medium, or long drying times.

You might think that this is just a clever trick to get more use out of an already efficient machine, but it’s not entirely that simple. For example, choosing short drying times doesn’t make much difference to a small load in which every item can dry quickly by itself. But if you’re doing a full load with a lot of items that aren’t completely dry after their own drying cycle, using short drying times helps avoid damage to delicate items like china and crystal. It also makes your dishes less likely to get smudged while they wait for the rest of the load to finish.