Residential pool salt water uses a salt chlorine generator for sanitation, maintaining a low salt concentration, typically around 3,000 to 4,000 parts per million (ppm). This is significantly lower than the high salinity of ocean water. However, even at this reduced level, the answer to whether pool salt water can kill grass is definitively yes. While small, occasional splashes are unlikely to cause significant harm, concentrated exposure from backwashing or consistent overspray is detrimental to both the grass and the underlying soil structure.
How Salt Water Damages Grass and Soil
The primary mechanism by which salt water harms grass is osmosis. When the concentration of salt ions outside the grass roots becomes higher than the concentration inside the plant cells, the salt pulls the water out of the cells to achieve equilibrium. This outward movement of water leads to severe dehydration, causing the grass to wilt and die as if in a drought. This condition is often termed “physiological drought,” occurring even when the soil is visibly moist.
The high sodium content also impacts the physical and chemical properties of the soil itself. Sodium ions displace beneficial elements, such as calcium and magnesium, from the soil particles. This displacement results in the breakdown of soil aggregates, causing clay particles to disperse and leading to soil compaction. Compacted soil severely reduces aeration and water infiltration, further inhibiting the grass’s ability to absorb water and nutrients.
Preventing Pool Water Exposure
Homeowners should manage pool maintenance discharge properly to ensure saline water never reaches the lawn. The most significant source of concentrated salt water exposure is the backwash from the filter, which should never be routed directly onto the lawn or garden beds. Instead, discharge the backwash line to a designated sanitary sewer cleanout or a containment area far from vegetation, following all local regulations.
For minimizing everyday splashing and overspray, installing physical barriers is highly effective. Landscaping elements like raised garden beds, hardscaping materials, or splash guards around the pool’s edge can intercept water. Any area that receives regular splashing should be immediately rinsed with a deep application of fresh, clean water. This action dilutes the salt concentration on the grass blades and flushes the sodium deeper into the soil profile before it can be absorbed by the root zone.
Remediation for Salt-Damaged Lawns
Once salt damage has occurred, the immediate and most effective step is to flush the affected area with copious amounts of fresh water. This process, known as leaching, works to dilute the accumulated salts and wash them downward, past the grass’s root zone. Apply several inches of water over a period of a few days to deeply saturate the soil and maximize the removal of sodium ions.
Following the initial flushing, applying a soil amendment like gypsum (calcium sulfate) is highly recommended. Gypsum introduces calcium ions into the soil, which are effective at chemically displacing the harmful sodium ions that are bound to the soil particles. Once the sodium is displaced, it becomes mobile and can be more readily leached out of the root zone with subsequent watering or rainfall. A typical application rate for gypsum is between 20 to 40 pounds per 100 square feet of damaged turf.