Our previous column showed that choosing one’s soaps and detergents can be complicated. Deciding whether to wash by hand or to use a dishwasher is similarly fraught because one’s usage of water and energy can render either method sustainable — or not.

Washing up manually can involve lots of water. According to New York City’s Department of Environmental Protection, leaving the water running while doing the dishes uses about 15 gallons of water every five minutes! One can save water by scraping away excess food before washing; filling a dirty pot with soapy water rather than an entire sink basin; and rinsing with the tap only after scrubbing everything. Recently, a friend who hand washes dishes this way used 1.5 gallons when washing up after one dinner and 2 gallons on another occasion (pots and pans included).

Perhaps counterintuitively, running a dishwasher need not waste water. These days an Energy Star-certified, standard-size machine requires less than 4 gallons for a full cycle. Be sure to scrape off the leftover food, avoid rinsing beforehand, and run the machine only when full enough to justify the water usage. If the contents of your standard dishwasher (35 inches tall by 24 inches wide by 24 inches deep) begin to smell before you can fill it, consider investing in a smaller countertop, compact, in-sink or slimline machine. Note, however, that these alternatives may not accommodate pots and pans and can require modification of your kitchen’s plumbing.

A second sustainability issue in one’s dishwashing process is energy use because heating water uses energy, as does running a dishwasher. For a limited number of lightly soiled dishes, hand-washing in cold water is an effective, energy-free solution. However, whether washing by hand or by machine, you may often prefer hot water because higher water temperatures help soaps and detergents cut grease and lift sticky foods. One can justify using hot water by doing so sparingly when washing up manually or running a machine only when full. Note that eliminating every last germ, though not necessary for people with healthy immune systems, requires water temperatures of 150 degrees or more. This is almost certainly too hot for gloved hands, but a dishwasher’s high setting should do the trick.

As for the tools needed for washing up, we will cover those soon enough!

David Conwell is a former history teacher who belongs to Brunswick’s Sustainability Committee and the nationwide advocacy organization Citizens’ Climate Lobby.