Pool water can damage or kill plants, depending on the chemical concentration and frequency of exposure. Pool water contains sanitizers like chlorine, stabilizing agents, and pH-balancing chemicals, which are designed to be hostile to biological life forms. When this water contacts landscape plants, these chemicals interfere with normal plant processes and cause tissue death. The severity of the damage depends on whether the pool uses traditional chlorine or a saltwater system.
Understanding Chlorine’s Effect on Plant Cells
The primary concern with a traditional chlorinated pool is the free chlorine, which exists in water as hypochlorous acid and hypochlorite ions. Chlorine is a powerful oxidizing agent that burns plant tissue on contact. This reaction leads to necrosis, appearing as scorched or bleached spots on leaves and needles that are frequently splashed. When chlorine-laden water soaks into the soil, it attacks delicate root cells. Root damage reduces the plant’s ability to absorb water and nutrients, leading to stunted growth and wilted foliage.
The concentration of chlorine is the main factor determining the level of damage. Pool water is typically maintained at 1 to 4 parts per million (ppm). For most plants, chlorine concentrations above 100 ppm can be toxic, and professionals recommend that pool water used for irrigation be below 0.5 ppm. Sunlight quickly dissipates chlorine, meaning an occasional splash is less harmful than a large, sustained runoff event.
The Added Danger of Saltwater Systems
While saltwater pools utilize chlorine generated from dissolved salt, the most significant long-term threat comes from the salt itself (sodium chloride). Saltwater pools maintain a salinity level far below that of the ocean, but the concentration is high enough to be detrimental to most landscape plants. This salt accumulates in the soil over time, creating a chronic problem distinct from acute chlorine exposure.
High sodium levels cause osmotic stress, where the salt draws water out of the plant’s roots rather than allowing water absorption. This reverses the natural movement of water, leading to physiological drought, even when the soil appears moist. Foliage often shows signs of “salt burn,” developing dry, brown edges or tips as the plant dehydrates.
Sodium ions compete with essential nutrients like potassium and calcium at the root uptake sites, leading to nutrient imbalance and ion toxicity within the plant tissue. This cumulative salt buildup makes it difficult for future plants to grow. For safe irrigation, pool water should ideally have a salinity level less than 1,200 ppm, and levels higher than this require specialized salt-tolerant plants.
Safeguarding Landscape and Garden Plants
Protecting plants from pool water requires both preventative measures and quick remedial action. Physical separation is the most effective prevention, involving planting sensitive species farther from the pool edge to avoid frequent splashing and runoff. Installing a low border or splash guard can also redirect water away from planting beds.
If a plant is splashed with pool water, immediate dilution with fresh, clean water is the best remedial step. Hosing down the affected foliage and soil quickly rinses away concentrated chlorine or salt residue before it can be absorbed or cause chemical burns. This minimizes contact time and reduces the chemical concentration.
For areas affected by saltwater runoff and sodium accumulation, the soil needs flushing. This involves applying large volumes of fresh water to the soil to dissolve the accumulated salt and leach it deeper below the root zone. Monitor pool chemistry, ensuring the water’s pH is within a neutral range of 6.5 to 7.5 before using drained water for irrigation, as highly acidic or alkaline water can also harm plant roots.