>>64623I've seen it done with a heated pan sealed apart from a downwards-sloping tube which drips into a bowl. No need for the sheeting in that case. You can also buy self-contained solar stills deisgned for emergency use at sea.
But to be honest I sort of agree with
>>64621in a less vitriolic way: you really only have to worry about this stuff if you know, for certain, that large volumes of high-end industrial waste is being dumped directly into the river. A shopping trolley or two will not do it, or even unscrupulous individuals dumping household waste. We're talking entire steel mills, tech plants, papermills, all without any semblance of regulation. That just doesn't occur in the UK. Same story for pesticides.