Many of us are concerned about the water quality in our homes. While our water may taste fine, the excessive minerals in it are causing premature failure in many faucets, water heaters, and piping. This is caused primarily by "hard water". Hard water is water that has an excessive amount of the minerals calcium and magnesium. These minerals are not dangerous to humans in small amounts however, they can wreak havoc on your plumbing system. Hard water also causes a host of other problems including dry skin, spotting on glassware, difficult to clean tubs and toilets, increased soap consumption and many more.
Water softeners solve the problem of hard water by a process called ion exchange. Ion exchange simply exchanges the hard water molecules for safe sodium molecules as the water passes through special softener. The level of sodium added to the water is so small that it cannot be tasted and is only detectable with specialized equipment. Once the water softener ions get saturated with hard water molecules (calcium and magnesium) the water softener flushes itself out with a brine (salt) solution and is recharged and ready to treat up to several thousand gallons of water before needing to regenerate again. This flushing process will discharge the leftover salty water along with the hard water minerals down the drain. This makes the whole process very easy for a homeowner. There are no filter changes. The homeowner simply has to add salt to a brine tank a few times a year.
Septic tanks act as holding tanks. As the raw sewage from your home enters the tank it slows down. The solids will sink to the bottom and grease will float to the top. The tank is sized so that the sewage will stay in the tank long enough so natural bacteria breaks it all down into liquid. If you significantly increase the amount of liquid going into the tank then the sewage will pass through it more quickly and you run the risking of passing solids and grease into the leach field. This can lead to costly repairs.
The discharge of water down the drain when a softener regenerates is a very controversial issue as to whether it is safe for your septic system. The answer is yes and no. It depends on the type of softener being used.
Many people have been told that water softeners are simply bad for a septic system. This is absolutely true if you have a water softener that operates on a timer. Timed water softeners are set to regenerate after a set amount of time whether the tank has reached its capacity or not. This is extremely inefficient and puts an excess of sodium and liquid into a septic system that may not be able to handle it.
The solution is a metered water softener. As the name implies, a metered water softener has a built in water meter that measures the amount of water that is used. The internal programming will determine precisely when the softener needs to regenerate based on the hardness of the water and amount have water that has been used. This greatly decreases the amount of water being used and completely eliminates any negative effects the water softener has on your septic system. Metered softeners also save the homeowners money by using significantly less salt than a timed softener.
If a home with properly sized septic system has an efficient metered water softener installed, the effect on the septic system is actually extremely beneficial! The amount of water added during regeneration is equivalent to doing one extra load of laundry every two weeks. The salt itself actually helps the solids settle in the tank which prevents them from leaving the septic tank into the leach field. The small amounts of water and salt has no affect whatsoever on bacteria levels.
Of course, good septic tank practice should always be maintained. This includes using a septic system treatment like Bio Clean to help break down solids and grease in the tank. Avoiding using garbage disposals, harsh disinfectants such as bleach, and never rinsing paint brushes in your sink. These are simply good rules to follow whether or not you have a water softener. Bio Clean alone can make up for a lot of bad practices because it adds significant amounts of septic cleaning enzymes directly to the tank.
The research from this post came from years of experience working with septic systems and water softeners. We have installed many water softeners in homes with septic systems with no problems at all. An independent study was also performed by The Water Quality Association and that study can be found here. https://www.wqa.org/Portals/0/WQRF/ResearchStudy_WaterSoftenersEnvironmentalImpact-ExecSummary.pdf