水だめ is read as みずだめ (mizudame) and means sump.
みずだめ
mizudame
みずがめ
water jug
みず
break granted to wrestlers engaged in a prolonged bout
すいしゃ
violent wielding of weapons
すいちゅう
underwater
すいき
water vapor (vapour)
みずいらず
(being) by oneself
みずき
dogwood (Cornus controversa)
すいじょう
aquatic
みずたまり
puddle
すいせい
aquatic (life)
みずいり
みずかさ
volume of water (in a river, pond, flood, etc.)