A hot hose is probably the simplest form of solar water heating possible. A good length of standard (ideally black) hosepipe is left in direct sunshine to heat up and the water it contains, when heated by the sun, can be used for an hot shower, to pre-heat water before it goes into a washing machine, and for many other uses.

Solar Hot Hose

Pictured above is a schematic diagram of a typical hot hose solar water heating system. Here 50+ metres of 1/2 inch diameter black hosepipe is connected at one end to a tap (or gravity fed from a rainwater collection tank ), with a shower attachment fitted to the other end.

When left in direct sun for as little as half an hour, the water can easily reach 40+ degrees Celcius. When the shower is turned on, the hot water flows out of one end and cold water enters from the other end ready to be heated. With 1/2 inch diameter pipe, every 10 metre length of pipe holds over 1 litre of water, so a 50 metre length will give a 5-6 litre shower.

As a 5-6 litre shower of very hot water is a lot less pleasant than a 10+ litre shower of pleasantly hot water, ideally a mixer tap should be used to enable cold water to be mixed with the hot water for the perfect shower temperature.

A much larger amount of hot water can be produced by increasing the length of hosepipe used. Good quality 500m and 1000m lengths of suitable hosepipe are sold by companies which supply commercial greenhouses and garden centres.