For those who have phobia using water heaters due to safety issue, can avoid water heaters. Just buy a medium-sized pail to store water. Whenever you want to take a warm shower, just boil some hot water using a kettle and pour the hot water into the pail of water. Just use a small bucket for scooping up the water from the pail to take a shower.

Some people can have this phobia of electrocuted by these water heaters as there are cases.

Solar heater is only practical to be installed at landed property, double storey homes or something similar. Not feasible for condominiums or apartments.

Okay. Don't know what is RCD though. Although the water heater comes with built-in RCD, there is a need to install an additional RCD so that the risk of being electrocuted by the water heater will be minimized to zero? Looks like additional cost to get the electrician to work on this apart from the additional cost in the RCD and the hacking of walls and stuff. So troublesome.