Water softening

Water softeners are essential to homes, schools, businesses and industry where the hardness ions, calcium and magnesium, would otherwise build up in pipes and impede the energy efficiency of hot water appliances (boilers, water heaters, etc.). Water softeners must be regenerated periodically and the resulting discharge stream returns the minerals calcium, magnesium, sodium and choride to the environment. These require proper management to avoid impairing drinking water quality, potential for water re-use and the efficient functioning of home onsite wastewater recycling (septic) systems.

Thus, there are three issues involving the use of salt to regenerate water softeners:

• Protecting drinking water quality both in the home and environmental sources of drinking water
• Preserving water quality for re-use by minimizing degradation due to softener discharges when the receiving waters are used downstream for irrigation, industry or drinking water
• Maintaining the efficiency of septic systems by ensuring that discharge of water softeners into onsite wastewater recycling systems does not cause an hydraulic overload, degrade either the septic tank or the soil structure of the septic drain field or destroy the active bacteria whose job it is to break down the wastes into harmless nutrients.

New developments in toxicity testing are giving us a better understanding of the impact of chlorides on the environment. The current US Environmental Protection Agency chloride toxicity criteria were established using a limited number of species in a distilled water-based medium. This resulted in conditions that did not reflect the real environment under consideration. When the water quality criteria were established, the EPA was unaware of the extent and the role of water chemistry on chloride toxicity. As a result, except where challenged, current standards do not reflect the mitigating impact of water hardness on chloride toxicity. In addition, when a broader number of species are tested, particularly those that are present in the location under investigation, more meaningful toxicity data are derived. Read more... (pdf 945.23 kB)