How Does Pool Water Affect Plant Growth?

Utilization

• Swimming pool water remains substantially water, with only minute additives to maintain sanitary conditions. The water retains its mineral qualities from its source, such as the municipal tap or irrigation supply or from a private groundwater well. As long as any additives, such as chlorine, are applied and maintained at the recommended levels, swimming pool water hydrates and fertilizes the soil and plant roots just like water from a hose.

Acid Formation

• The addition of chlorine to pool water isn't harmful to plants. Chlorine, in the form of chloride ions, is abundant in most soils already. It takes tremendously high amounts of chloride to manifest as any negative effect on plants — conditions that don't exist with chlorinated swimming pools in the United States. However, when chlorine gas is added to water, some chemical reactions occur to create hypochlorous acid. The small amounts of acid that exist in pool water, as well as any salts that form with the fusion of chloride ions with dissolved minerals, can be problematic for plants.

Plant Sensitivity

• Improperly maintained pools, such as when too much chlorine is added to the water, can lead to damage to plants. Higher concentrations of acids and salts in pool water may cause brown leaf edges, yellow or brown splash marks or stunted growth. If chlorine gas levels are so high that they create a smelly air around the pool, they may slightly diminish metabolism in plants, as there are fewer carbon dioxide molecules in the air to absorb, and more chlorine gas instead. Sensitivity to pool water varies widely among plants. One species may quickly develop scalded leaves or burned root systems from the acids and salts, while others may be inundated and show no sign of stress.

Effects

• Occasional watering from a swimming pool shouldn't hurt nearby plants, including lawns. Depending on the plant's species-specific tolerances to acid and salts, the first signs of trouble are usually seen as wilting. When the plant roots are damaged, they cannot absorb water in large enough amounts to sustain the foliage. Too much splashing by swimming pool water can suffocate plant roots as well. Some plants need a well-drained soil. If the soil is wet all the time, some plants will decline because their roots cannot exchange gas in the normally porous soil. The effect also starts off as plant wilting and progresses to leaf drop, leaf yellowing or stem dieback.