I know this is very specific, but I was looking for a translation for standing/stagnant water (context: mosquitoes), but found out it `死水｀(if that's incorrect though, someone please kindly notify me). However, a new question popped up. What is the verb used for handing 死水？ In English, I would say something such as "get rid of".
死水 usually refers to the water size of a pond or lake. You probably want to use
积水 instead. Then you can say
清除积水, for example
扔掉 - an action of
throwing away. You can't grab water and throw it, so it's not suitable
倒掉 - to
pour out / away. It make sense to use 倒掉, but a common way will be what most other answer suggested - 清除 - to clean up
Also stagnant water = 积水
I think 清除 is a good choice as answered by Wang Dingwei. By the way, since 死水 can also mean water or even liquid that is not fluid. And it's often used to reference the dirty water.