A lot of people are surprised when they come to Costa Rica and find that the only hot water is in the shower. This can require some mental adjustments, especially if you are used to washing clothes and dishes in hot water. Most people's first thought is "gross!" how do you get anything clean!?
For me, washing clothes in cold water is nothing new - we did it this way my entire life. It saves energy, and doesn't make much difference in the cleanliness.
Dishwashing was an entirely different story though. It took me a while to get over that icky feeling of washing dirty dishes in cold water. True, the soap in Costa Rica is specially formulated for cold water, and the dishes *look* clean, but what about germs? Could 4 million Costa Ricans be wrong? Well, guess what I just found - a study :D.
The FDA recommends washing dishes in 110 degree F soapy water, rinsing, then soaking in sanitizer. Ohio State University researchers added bacteria to dishes with dried-on food, and found that these dishes washed in soapy room-temperature water, rinsed, and then weakly sanitized with ammonium-based chemicals achieved FDA-acceptable results.
However, dishes that were especially difficult to get clean were forks, because food stuck to the tines. Also, milk-coated glasses hung onto the bacteria more than any other food.
Recommendations from the study were to
1) spend extra cleaning time on forks
2) wash dishes right away before food dries - this saves washing time and gets rid of problematic places where bacteria might be able to survive washing and drying
My added recommendation is to rinse and/or soak dishes if you can't wash right away - this keeps the food from drying on the dishes.
Of course, some people go whole hog and get a hot-water heater connected to a dishwasher...