Recycled water feature?

I have been wanting to add some water for increased biodiversity to our garden for a while but have been wary of open water due to small children concerns. 
I have recently had a thought due to some recycling opertunities coming along. 
I have a broken recycling box which is split down one corner and not useful as a recycling box any more. Also due to some recent house refurbishment and some hard landscaping I have some thick black plastic to use and a large quantity of rocks and stones of differing sizes. 
My thoughts are could I effectively make a submerged sump with the box and plastic, fill it with stones then fill with water? 
Could it be useful as a source of drinking water for birds, insects etc? Would it be useful at all and if so how?