Water Softeners

The wastewater created by water softeners is often times released into your septic tank. This discharge creates an additional load on your septic system as your tank must accept and process the additional waste.

Studies have been conducted regarding the effect of softener waste on septic systems. Generally, provided that your system was designed to accommodate the extra 5-10% of water generated by a water softener, your system should not be adversely affected. The findings are described in detail in this report by the Ontario Rural Wastewater Centre at the University of Guelph.  

Some homes contain a grey water system in addition to a septic system. Ideally, a grey water system would accept any waste from the water softener in order to completely eliminate the risk of any adverse affects to the septic system.

The Ontario Rural Wastewater Centre provides the following tips for the usage of a water softener in conjunction with your septic system:

1. A more efficient water softener will reduce the amount of sodium chloride used. In general, new water softeners are more efficient than older models.
2. The softener should be set to regenerate depending on the water flow instead of being set to regenerate at regular time intervals. This ensures that regeneration occurs only when required.
3. Water conservation practices should be established to reduce the quantity of sodium chloride sent to the septic system.
4. Soften only the water necessary. For example, outdoor water does not need to be softened.
5. Potassium chloride may be used instead of sodium chloride in the water softener. Although potassium chloride is about twice as expensive as sodium chloride, its use will reduce the quantity of sodium sent to the septic system as well as the quantity of sodium in the diets of residents. As well, far more potassium is needed than sodium to cause the same deleterious effects on soil hydraulic conductivity.
6. Design the septic system to accept the higher hydraulic load due to water softener (increase 5-10%).
7. In constructing a leaching bed, avoid using soils with high contents of swelling clay (montmorillonite). This will reduce the detrimental effects of sodium on hydraulic conductivity. However, soils with high clay contents have lower hydraulic conductivities than non-clay soils and should not be used for leaching beds anyway.