Yes, it's generally a good idea to add salt to the water when boiling potatoes for mashed potatoes. Adding salt to the water enhances the flavor of the potatoes as they absorb some of the salt during the cooking process. This step can help ensure that your mashed potatoes have a well-rounded and delicious taste.
To do this, simply fill a pot with enough water to cover the potatoes, add a generous amount of salt (about 1-2 tablespoons of salt per gallon/liter of water), and then bring the water to a boil. Once the water is boiling, add the peeled and diced potatoes and cook until they are tender enough to mash easily with a fork or potato masher. Be sure not to overcook the potatoes, as this can result in a gummy or watery texture for your mashed potatoes.
After the potatoes are cooked, drain them well and proceed with your preferred mashed potato recipe, adding butter, milk or cream, and any other desired seasonings to achieve the perfect consistency and taste.