Bad Elements

For more then 30 years we had no problems with elements in our area (Kathu,Northern Cape) now all of a sudden the elements last max 3 months, the only reaction we get from kwikot is that our water is to hard for the elements , no refunds . I don't know how can it be that in 1 years time the water can be so different that the element can not last. Me personally think that the manufacture a bad element and don't want to be responsible for it and give every possible reason not to replace or refund any.