Install a Water Softener - Are Water Softeners Bad for Septic Systems - Water Quality Research Foundation

We own a small four-level home and would love to install a water softener. However, we are on a septic system and the lowest level (basement) has no drain since it would be lower than the septic tank input. There isn't any place other than the basement to have a water softener.

Are water softeners bad for septic systems? When a water softener recycles, can it pump up to the drain pipes in the ceiling of the basement or would that require a special pump?

Thanks for your interesting question. I'm reading between the lines here, but it sounds as if you or a family member like the way skin feels after a shower in softened water—clean and silky smooth. Let's see if we can make it happen for you.

The good news is that a water softener will not harm your septic system. According to a report issued by the Water Quality Research Council (now known as the Water Quality Research Foundation), water softeners do not have any detrimental effect on septic systems. The report also says that the discharge of minerals and sediments may actually enhance septic tank performance in certain situations by encouraging the growth of additional bacteria.

The flow from a softener is typically less than the wastewater discharged from an automatic washing machine. The studies credited the high levels of calcium and magnesium present (in the flow that results when the softener cleans itself) with improving soil percolation in many instances. To learn more about research report No. R12, Water Softeners Pose No Problems for Septic Tanks conducted by the Water Quality Research Foundation, go to the Water Quality Association's website www.wqa.org to read the report.

The other good news is that a special pump won't be necessary. A softener unit creates enough pressure on its own to discharge the waste up to 20 feet away. So yes, it could be drained up into a washing machine drain standpipe, for example. The drainpipe needs a minimum 1 1/2 inch net opening. Because there will be so much pressure on the flexible plastic drain line, make sure it's secured in place.

Be sure to leave an air gap between this drain line and where you run it into a waste drain to prevent any possible back-siphoning. An air gap space of 1 to 2 inches should be plenty, but check with your local plumbing codes. By the way, because a water softener is a plumbing fixture, a permit will be required. Also, if the discharge line has to travel a 20-foot distance, use a rigid pipe (PVC or CPVC) to prevent kinks in the line. Upsize the diameter to allow the resin (mineral) tank to clean better. In a case like this, have a licensed plumber install the water softener.

Now comes the tricky bit: where to place the water softener so you do not exceed 20 feet for the drain line. If it's any help, the brine (salt) tank can be located up to 20 feet away from the softener mineral tank. Consider positioning this tank in a garage to make it easier to fill the tank with salt. It's a lot easier to transport bags of salt from your vehicle to a brine tank in the garage than to lug the bags to a tank located in the house. However, now that I have suggested it, I also have to caution you as well. The plastic water line running from the softener to the brine tank will freeze if the room is not kept warm during the winter months.

The weekend's here—are you ready to install that water softener?

[ Back to Top ]

C.R.S., Inc. · Spokane, Washington · USA