There was a time when hefty large water storage and heating systems were the only option people had. It was a sorry option too, at that. Because the overly large storage tanks inevitably lead to wastage of both water and electricity that was used to heat that water up. Because it was simply not possible to use that amount of hot water in a given time. Thus the water would go cold and would be wasted. So families would lose electricity and water would be wasted, which is very bad in a world where water is not freely available to everyone.
But today people have a better option of choosing the tankless water heater which is also a water heather but with a smaller and more functional storage tank. The storage stank is not gigantic and thus only the amount of water needed at any given time could be heated and thus neither excess water nor extra electricity would go to waste thus serving both the people and Nature.
These units are used for other purposes too apart from in homes and offices. They are used as marine tankless water heater too as they are very functional, convenient and efficient. Hence, they are also widely replacing old storage tank water heaters as industrial water heaters too. These water heathers are a great option and much, much better than the old large storage tank heathers as they are smaller in size and also never give rise to any water springs and leaks unlike the storage tank water heaters. They save electricity and water and hence people save money as well as help people save Nature by not wasting her precious resources thanks to cumbersome faulty old machinery. So it is best to switch from old water heather to new tankless heaters.