As a rule of thumb, if your water supply is normal water also known as fresh/ soft water, you can pretty much use any model of instant shower that pleases you; without worrying about damaging the heating element.
-8%
Original price was: KShs 6,000.KShs 5,500Current price is: KShs 5,500.
-20%
Original price was: KShs 6,000.KShs 4,799Current price is: KShs 4,799.
-12%
Original price was: KShs 8,500.KShs 7,500Current price is: KShs 7,500.
With normal/ fresh/ soft water, you can use any instant shower/ heater without worrying about the element. With proper installation/ use, a good quality instant shower will serve you for a very long time.