SOFT WATER AND SEPTIC SYSTEM OPERATION
Areas that have hard water often want to improve the quality of water for household use with water softeners Consumers now have a choice of water softener regenerant to remove the hardness ions calcium and magnesium) and replace them with softness ions. Potasslurn is the softness ion when Softouch is the water softener regenerant and sodium is the softness ion when sodium chloride is the regenerant. Potassium has fewer environmental effects particularly when the household has a septic system for treatment of their wastewater.
This is because: 1.) Potassium is a nutrient required by the normal bacteria present in septic tanks that aid in the digestion of wastes. Some of the potassium in the soft water is taken up by the bacteria and removed from the water. 2.) In the septic drainage field, potassium is a plant nutrient removed from the soil by lawn and yard plants. This decreases the amount that percolates through the soil to the ground water. 3.) It has little potential to decrease water percolation rates through the soil beneath the septic seepage field. Potassium can be partially filtered out of the drainage water by soil clay particles and less leaches through the soil to the ground water. From an environmental standpoint, potassium, as the water softness ion, has several advantages over sodium.
POTASSIUM AND SODIUM EFFECTS ON THE SEPTIC TANK BACTERIA
Septic tanks are sewage disposal systems for private homes that are not connected to municipal sewage Systems. A properly designed septic tank is large enough to hold 3 to 5 days supply of wastewater from the household. This allows the bacteria in the tank to partly break down the wastes. In the tank, the oils and greases float to the surface of the water and form a scum layer. The heavier materials sink to the bottom to form the sludge layer. Bacteria live in these layers and in the water to break down the wastes in a digestive process, The wastewater becomes ciarifiel and partially purified before it is discharged into the septic drainage field.
Bacteria that live in the septic tank remove some of the potassium and sodium from water. Potassium is a nutrient required for life processes. Research studies with sodium conducted by the National Sanitation Foundation, have found that bacteria thrive at the levels of sodium added to septic tanks by soft water. Even the addition of the regeneration waste stream from recycling the water softener was beneficial to the bacteria. Their research findings stated that bacteria operate most effectively at concentrations about 10 times the levels of sodium found in soft water Bacteria can adapt to levels 80 times higher in concentration. Addition of potassium or sodium to a septic system by the use of soft water actually has the beneficial effects on the digestion of wastes by bacteria.
The studies also showed that the sodium was partially removed from the water before it flowed to the drainage field. The sodium was relocated in to the scum and sludge layers in the tank. Average sodium chloride concentrations were 1.2 percent. Similarly potassium would be removed from the water by the bacteria and relocated to the scum and sludge layer. The actual amounts are not know since it was not included in this study, but it should be removed by the bacteria in the septic system. Potassium and sodium softened water increase the biological action of the septic tank to break down wastes.
EFFECTS OF SEPTIC TANK EFFLUENT ON DRAINAGE FIELDS
After the sewage water is clarified and partly purified in the tank, the effluent water flows through the distribution pipes and drains through the soil in the seepage field. The soil beneath the drain pipes must remain porous and permit the percolation of water for the system to remain in good operating condition. Potassium, as the water softening ion, will have less effect on the soil pore space and water percolation rates than sodium for thnee reasons. 1.) Potassium has less ability to cause soil swelling. That doses soil pores and reduces soil percolation rates. Soil pores act as channels for the flow of water. With potassium in the water, the pores stay open to a greater extent than for sodium. Sodium softened water can decrease soil space and permeability to water flow by 15 percent due to soil swelling. 2.) Soils filter out more potassium than sodium from the water flowing through it. Potassium can become chemically fixed in some soil clay particles. This removed it from the water that is percolating toward the ground water and decreases the amount moving into the ground water. 3.) Lawns and yard plants take up potassium and use it as a plant riutrient. Plants take up potassium through their root systems and move It to the leaves and stems. The removal from the soil and into the vegetation means that less potassium stays in the soil to potentially leach into the ground water. Many lawn and yard plants contain between 2 to 6 percent potassium. Thus, the potassium found inside the lawn and yard plants is removed from the soil in a septic drainage field. This means that less potassium remains in the septic tank effluent as it percolates through the soil to the ground water. Therefore, potassium found in Softouch has significant environmental advantages over sodium as a soft water regenerant.
EFFECTS OF POTASSIUM OR SODIUM ON ALGAE BLOOMS IN LAKES
Sometimes effluent from septic systems tends to flow laterally beneath the soil and emerges in lakes or rivers. If the water is softened with potassium or sodium, the lake or river will not develop an algae bloom due to the presence of either potassium or sodium. Algae require high levels of nitrogen, phosphorus, and soluble carbon in the water to promote formation of the algae bloom. While potassium is a required nutrient, its natural concentration in lakes and rivers is high enough to support normal algae growth. Additional potassium from septic system effluent will not affect normal algae growth and will not cause an algae bloom, nor will sodium.
CONCLUSION
Long term operation of a septic system with potassium softened water will result in some potassium moving into ground water or into lakes and rivers. This amount is minimized because potassium is taken up by bacteria In the tank, it is taken up by lawn and yard plants, and It is fixed by soils that act as filters in the drainage field. These remove it from the effluent water percolating through the soil in the drainage field and minimize the amount that moves into ground water. Softouch, which is used for regeneration, is an environmentally sound choice for softening water.
Dr. Charles Harms
Market Research & Development Manager
IMC Agribusiness
LaFayette. IN