Handheld garment steamer and water tank thereof

A handheld garment steamer, comprising:

• a housing comprising a base housing portion and a head housing portion transversely connected to said base housing portion;
• a water tank detachably mounted to said base housing portion in a manner that said water tank and said base housing portion form a handle part for a user to hold thereon, wherein said water tank comprises a tank body comprising a lower portion, and a seat tank portion extended from said lower portion of said tank body, wherein said water tank is detachably mounted to said base housing portion in a manner that said base housing portion is supported above said seat tank portion at a side of said tank body, wherein said tank body has a first receiving cavity, said seat tank portion has a second receiving cavity, wherein a height of said second receiving cavity is smaller than a height of said first receiving cavity, wherein said second receiving cavity is communicated to said first receiving cavity to define a water storing cavity of said water tank;
• an evaporation assembly installed in said head housing portion;
• and
• a water pump assembly for pumping water in said water tank to said evaporation assembly, wherein said water pump assembly comprises a delivery pipe, a water valve, a coupling pipe, and a pump element, wherein said delivery pipe is disposed in said water storing cavity of said water tank, said water valve is connected to said delivery pipe and is installed to said seat tank portion of said water tank at a position under said base housing portion, said coupling pipe is detachably connected to said water valve when said water tank is assembled with said base housing portion, said pump element is operatively coupled to said coupling pipe and is disposed in said base housing portion at the side of said tank body.