Photo: …love Maegan/Flickr

Americans, on average, do about two and a half loads of laundry per person per week, according to water conservation analysts. That can eat up about 22 percent of your household’s water use, and if you’re not using the right type of detergent, you could be wasting even more water in the form of overly diluted liquids or extra rinse cycles to remove powder residues from your clothes. There are plenty of detergent brands to choose from, but a good start is to think about what form your detergent comes in — powder or liquid.

Pros: Ingredients like bleaching agents and surfactants (the substances that get your clothes clean) are more stable in powders, and therefore, they have a longer shelf life than liquids. You can buy powders in bulk — and cut down on excess packaging — without worrying about the detergents becoming ineffective over time.

Cons: Use too much, and you’re left with cakey white gunk all over your clothes—which requires extra rinse cycles, and thus more water. Also, in order for some powders to dissolve completely, it’s better to use warm water, and that can waste more energy than washing in cold water — something that is easy to do with liquids.

Pros: Liquids dissolve better in both cold and warm water, so you don’t have to worry about residues left on your clothes.

Cons: It takes water to make liquids … liquid. In fact, standard, nonconcentrated detergents contain as much as 80 percent water. It’s a waste of both water and energy to truck diluted detergents around the country when your washing machine does an efficient job of turning powders into liquids with the water that comes from your local supply. Also, according to a recent analysis by Consumer Reports, those liquid laundry caps can lead to serious overdosing, costing you money and gunking up your machine. The measurement lines are rarely marked clearly, they found, and it’s hard to figure out how much is the appropriate amount for a small, medium, or large load of clothes.

The verdict?

Go with powders. You can dilute them yourself, and with careful dosing, you won’t wind up with powdery residues on your clothes. The key is to use less than you think you need, and to buy a brand formulated for use with cold water, such as greener products made by Planet, Ecover, and Seventh Generation. Fortunately, the scoops you get with powders are easier to read, so you’re less likely to OD on detergent.

And throw a half-cup of white vinegar in the rinse cycle. Sometimes powdery deposits come from minerals in hard water that combine with detergents and redeposit on your clothes, not from the powders themselves. White vinegar helps remove hard-water residues, as does letting the powder fully dissolve before putting your clothes in the wash (for people with top-loading machines).

If, however, you’re a liquid lover and can’t bear to part ways with that plastic bottle, buy a brand that comes triple concentrated, like the laundry liquids made by Method, or a double-concentrated product, rather than one sold full-strength. They use the least water and packaging.