Complex sentence: In every palace had wells, so especially drawing water and delivering it to needed places were regarded important in their duty, so "musuri" were also called "susa" (水賜, literally "giving water").
Split into simpler sentences: In every palace had wells, so especially drawing water and delivering it to needed places were regarded important in their duty. For the reason, "musuri" were also called "susa" (水賜, literally "giving water").