Green stuff growing in water butt

[noviceveggrower]

Hi everyone,
Am getting a second plot that has a shed with water butts with it. The water butts don't have lids on and it looks as if they have pond weed growing in them.
So was wondering is it still on to use this water, how can I get rid of it and how can I make sure it doesn't come back as in do I need to scrub the butts out with something to kill the weed off?
Will be getting lids for the butts when the plot becomes mine but want to be ready to sort the butts out as well.
Thanks

[Veggielot]

You could probably use the water, but the from the sound of it you will want to give them a clean. Given the current weather I would just empty them and clean them now you will soon fill them again.

[rustylady]

It's probably duckweed - I have it in a couple of mine. The water is fine to use, but the weed will clog up the rose of the watering can

[noviceveggrower]

Is it best to use just plain old water and elbow grease to scrub the butt out or is there something I can use or put in it?

[chris]

Just scoop it off the top - compost it. I do -it's all over my open barrels on my plot.