What effect does chlorinated water have on plants?

Written by marynia kolak | 13/05/2017
What effect does chlorinated water have on plants?
Plants do best with water that's free from chlorine. (pots & plants image by FotoWorx from Fotolia.com)

Chlorine, which is commonly found in municipally treated tap water, can hinder the healthy growth of plants. While its effects may appear slight, many seasoned gardeners and vegetation enthusiasts seek to avoid the use of chlorinated water when irrigating plants.


Chlorine is commonly added to drinking water at municipal water treatment plants to prevent harmful bacterial growth. It takes less than two units of chlorine to disinfect one million units of water.


The environment in which plants grow is rich with microorganisms and bacteria. Chlorinated water may disturb healthy bacterial growth and harm beneficial microorganisms. It can also prevent nutrient uptake essential to the growth of the plant, as well as alter pH levels.


While chlorine is necessary for plant processes like osmomis, ionic balance and photosynthesis, too much or the wrong form of chlorine can impede plant growth. Negative effects include slow or uneven growth, and a generally unhealthy appearance. Excessive chlorine causes root injury.

Prevention and Solution

Methods of reducing chlorine's impact include using water softeners or reverse osmosis filters, or allowing the chlorinated tap water to stand in an open, aerated container for two days.

Expert Insight

Gardeners working with sensitive species of flora can circumvent the problems of chlorinated tap water by using rainwater to irrigate their plants. Rainwater can be collected in rain barrels and mixed with a compost tea, the residual liquid of a compost bin, to harness the most nutrient-rich water source.


In the food processing industry, produce may be treated with chlorinated water to reduce pathogens and other microorganisms that can be harmful to humans when consumed.

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