shower pan       
noun [ C ] US uk/ˈʃaʊə ˌpæn/ us/ˈʃaʊ.ɚ ˌpæn/ (also shower base); (UK shower tray)
 淋浴盆(淋浴室中侧边高于地板的金属盆,盆中安有地漏)
the flat part of a shower, that you stand on
  Leaking pipes and shower pans are common sources of water damage in homes. 破裂的水管和漏水的淋浴盆是家庭中常见的水损坏来源。 
 The shower base forms the foundation of your shower enclosure. 
 - More examples
 - The plumber recommended that the shower pan be replaced.
 - Kits that separate the wall and shower pan and doors are expensive.
 - The caulk seal was not forming a good seal between the shower wall and the shower pan.