A small simple solar water heater

This is a very tiny solar water heater that will give enough water for a quick wash. You'll need a 1 litre bottle, a 2 liter bottle, some black poster paint or something to make the 1 liter bottle black, I used a bin/garbage bag.

Cut open the 2 liter bottle at the about 2/3 of the way up. Cut 4 small slits around the top of the bottom 2/3 bottle.
Paint or cover the one liter bottle so it is black. Fill the 1 liter bottle with water, place inside the 2 liter bottle and place the top 1/3 on. Leave out in the sun and after about 3 hours the water will be nice and warm. Becareful if leaving the bottle out for longer as the water does get pretty hot.

I used a 1l lucozade bottle and a normal 2 l lemonade bottle for the above.
After experimenting with a 2l and 3l bottle I found that same size bottles don't fit. To get around this you could cut a band out of another 3l bottle and tape it to the main 3l bottle or try and find 3l and 2l bottles of different heights, give me a shout if you do.

With some wood and a bit of glass or Plexiglas you could make a bigger solar water batch heater that could heat 3 to 6 or more 2l bottles of water, enough to do the dishes and get a wash. I think I'd use glass bottles if making this as the water does get hot, very hot. Make a box with the wood and cover the front with the glass, have a way to angle it towards the sun. Simple, even if my explanations aren't.

Please leave any comments if you have any problems or suggestions, thanks.