Thanks for this thread, it's reminded me to dig my black shower bag out, and I've also ordered a new one for £4.64 from ebay (I shop online mainly as I live rural)
eBay - The UK's Online Marketplace
And the cheapest I've found the 12v shower for is £14.99 on ebay
eBay - The UK's Online Marketplace
Maplins (or napkins

? ) is out of stock online so I guess all their old stock is gone now.
I thought about getting one of these last year before I got my Transit but wasn't convinced that they would be much good. If anyone can recommend them, I may get one. It would be really handy for muddy boots and paws, although it's probably too late now for my Peugeot Partner which has endured 10 years of muddy dog walks, but it would help keep the new carpet (which I'm hopefully laying this weekend

) clean in the Tranny. And with the back doors of the Transit open and a curtain up across them, I've got my own spacious shower cubicle
I'm hoping to replicate a similar solar water heating system in my back yard for my hot water in the house during the summer - my hot water comes from a back boiler on my woodburner, which is great during winter as I have constant hot water. But in the summer when the stove is only lit for a couple of hours at night, or not at all, I have to boil the elec kettle for the water to be hot enough to wash up in. At under a fiver each, the cheapest solution may simply be 4 or 5 black solar shower bags hanging from the yard wall, strategically placed to catch maximum sunshine at different times of the day as the sun passes overhead. Plus maybe a tenner for tubing and tap, and silver foil behind them, it shouldn't cost more than about £35 for (potentially) up to 100L of warm / hot water. That would probably pay for itself in wood and coal saved, and elec used, by the end of the year :banana: (so long as I have got my maths right....

)