The Effect of Sodium Salt on Septic Systems
Common knowledge supports that higher levels of sodium salt can have a direct impact on bacterial life forms. For instance, most bacteria usually found in fresh water ecosystems would be unable to live in a high salinity environment like an ocean. For this reason, concern was generated that septic systems that rely so heavily on bacterial action may be effected by high concentrations of sodium.
These concerns seem to be unwarranted. First, a typical residential sized water softener discharges between 40 and 70 gallons of water per regeneration. Through much of the regeneration process, fresh water is discharged, containing no salt at all, so the total concentration of salt is very dilute. However, during some stages of regeneration, the sodium concentration can reach as high a 5,000 to 10,000 ppm for brief periods of time.
To see if this level of sodium effected microorganisms typically found in aerobic on-site septic systems, a study was performed that exposed these microbes to a worst case scenario of 10,000 ppm brine solution. The study concluded that “there were no statistically significant differences in the metabolic activity of the microbial communityâ€, and that it was “unlikely that failures in domestic water treatment system are the result of exposure to the brine from home water softeners.†(1)
Other studies indicate that the effect of putting softened water into septic system can actually be beneficial. There is a very low amount of sodium contained in softened water. For every grain of hardness removed, approximately 8 ppm (parts per million) of sodium is added. Although some naturally occurring water sources have very high sodium levels, softened water normally has a slightly elevated sodium level vs. untreated hard water. While this concentration is normally insignificant at typical hardness levels, these higher sodium levels are more in the optimal range for septic system bacterial growth, and can promote bacterial development.(2,7)
