Skippy, I think you mean Carbon Monoxide...
It's way more toxic than Carbon Dioxide.
Gregg
Hi Greg yes you are correct Monooxide is for more deadly.
Just as an add on to the debate. The people who have mentioned that the hot water does not last for more than one showere with an electric heater and a tank.....this can be because the tank is too small and or the problem I mentioned about cold water pressure. If you have a higher pressure in the cold system then the hot when you mix the two together like in a mixer shower sometimes the back pressure of the cold water defeats the hot and you get cold water entering the storage tank making all your hot water cold very quickly. You may need to insall non return valves or check valves
You must also check that the tank is not full of calcuim build up which is common after a year or so of use.
Solar power can be very good if you use it to generate electricity just for the heater. I am not sure of the available options here but I know in the states or Europe you can get some great deals on these kits.
Advice on cold water storage tanks on the roof. It always amazes me to see how some people use these. Water stored on the roof in black polytanks can be dangerous.....legionalla is a danger where you get warm water that does not circulate. Only a problem in spray form, like showers. I am surprised there are not more problems here with this. Do not put your cold water tank in full sunlight if possible cover it and do not use a tank that is too big for your daily consumption...remember you must keep the water turning over and not let it get stagnant.
Propane Hot water on demand heaters are ok just install correctly and maintain them they are deadly if left to themselves and poorly maintained.
The small electric add on heaters for the shower are not a good idea even if you install correctly the electrical systems in some houses and apartments are sub standard with little or no Earthing (grounding) in the bathroom areas of the rest of the house for that matter. The use of plastic pipes makes it difficult to bond the water supplies so you risk a shock from a faulty device. And believe me the show is the worse place to experiment with your bodies ability to pass current.
Check your electrical systems to see if you have a residual current device and if not fit one or if yes check that it works........ regularly.
Skippy1
Just for information I am a Counsultant Engineer Qualified and Chartered, Masters degree from University of London and BSc in Electrical Engineering, with 36 years experience should anyone want or need specific advice I would be more than happy to help if I can.