You should be very careful when choosing a water heater. There are two types of water heater one which used electricity and the other one using gas. I personally, will confide anyone who wanna buy a water heater to buy the one which makes use of gas.
It is safer than the other one as a dilemma had already happened at home one or two years ago. My mum was having her bath at around 9.00 pm when suddenly I heard her screaming. Since she liked joking, my dad and my sis and even me were stunned, and still watching the tv. We then hurried to the bathroom, where by chance mom had not locked the door. I grabbed the shower handler which was in her hand and I felt that high electric voltage in my hand too.
We removed her from the bathroom as she was about to faint. After a few minutes, I felt an electric shock in my electric oven too and told my dad to switch off the central. Since that moment, the same night, I took a knife and cut all connections to that water heater which we had since 5 years and the day after, dad went to the shop and bought a gas water heater. So, please beware and listen to me as many people have lost their life coz of electric shock. By God grace, my mom is ok.