Chlorine in Hydroponics

Many people worry about chlorine in tap water. They think it will hurt their plants. In most cases, this is not true.

Chlorine is added to city water to make it safe to drink. It kills harmful bacteria. The amount used in tap water is small.

If your water is safe for you to drink, it is usually safe for your plants.

In basic hydroponics, small amounts of chlorine do not harm plants. Most growers use tap water without problems.

Chlorine can matter in special cases. For example, if you are using helpful bacteria or running a “living” system, chlorine may reduce those microbes. But in simple systems with bottled nutrients, this is usually not a concern.

Some cities use chloramine instead of chlorine. Chloramine stays in water longer. Even then, the levels are normally low and safe for plant growth.

Some people let their water sit out for 24 hours before using it. This can remove chlorine, but it does not remove chloramine. Others use filters or reverse osmosis water. These steps are optional for most beginners and can cause new problems.

The biggest water problems in hydroponics are usually high mineral levels, high sodium, or wrong pH — not chlorine.