Descaled water - really necessary for plants?

Again and again there is evidence that you should boil water for watering plants, let stand or soften, so it does not harm the plants. Whether that's true, what each method does, and what can hurt plants the most is explained here.

Lime and plant damage

Lime in tap water is not fundamentally harmful to plants. In nature, they are supplied exclusively with rain, which is basically distilled water, but that does not mean that they would not tolerate the minerals contained in tap water.

On the contrary - plants, like most living organisms, need a variety of minerals in order to maintain their metabolism. Normally, these minerals are extracted from the soil or substrate. When poured with tap water, the minerals in the water accumulate in the soil and the risk of deficiency symptoms is lower.

Lime harms most plants only in excess - approximately from a water hardness of about 20° dH upwards. Only a few sensitive plant species (such as orchids) tolerate significantly less lime in the water. Even in case of damage, the lime causes only a poorer nutrient absorption.

Allegedly effective methods for decalcification

Grandma's sewing box knows a variety of methods to make irrigation water "lime-free". Not all work as planned.

Let stand

The leaving of irrigation water removes only the volatile compounds, including chlorine, which many plants can not tolerate. So much chlorine is used today in drinking water but hardly that would be necessary.


The boil off actually reduces the water hardness. However, only the carbonate hardness. For very hard water that is too little, for other water superfluous.


The correct pH of the water is very important for plants. Therefore, sometimes the water is acidified, such as with vinegar, if the pH is too high. Rain has a pH of about 5.5-6.5 because it contains no minerals. The method is controversial.

Tips & Tricks

The easiest way to treat very hard water for pouring is to mix one-third of distilled water with tap water.

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