Because the salt concentration of water softener discharge is much higher than the salt concentration within the grass, the cells of grass will try to equalize these concentrations through a process called osmosis.

It is difficult for the cell walls to let the salt molecules in therefore it reduces the amount of water within the cell instead, effectively drying out your grass.

The small amount of salt that does get into the cells will also negatively affect the functioning of the grass or possibly kill it, just like high salt intake negatively affects humans.

The Problem With Draining Your Water Softener Outside

Whether you're out and about or living in a remote area, if your water softener is not connected to a regular sewage system or doesn't have a suitable drainage option in place it can be difficult to figure out where to discharge your water softener backwash. You might be thinking about pouring it out over your lawn, however, that could be the end for your well-maintained pitch of grass before you know it.

There is lots of anecdotal evidence about using discharge to water the lawn the outcomes however differ widely. Some stories say the grass is dead within days while others say it's as green as ever. As always the key is in the details, too much of anything is bad and the solution to pollution is dilution.

Spreading out the backwash over large areas and using it for watering your lawn as it's about to rain will help to dilute the salts. If it's a prolonged dry period dilute the salt concentration within the backwash by adding more salt free water.

Will Water Softener Backwash Kill My Grass?

Yes eventually and without any precautions, when watering your lawn with the backwash from your water softener the salt will probably kill your grass.

As water drains into the soil and is partly taken up by the grassroots, the salt within it is filtered out by the soil and remains there. Each time you water your lawn with water containing salt, the concentration of salt within your soil is increased.

Why Will Water With Salt Kill Grass?

As the salt concentration within the soil beneath your lawn increases over time your grass will start to take up less and less water, or even expel water, until it either stops taking up water or starts taking up both water and salt.

As you can imagine without water the grass will stop growing and will eventually dry out and die. However, even if it takes up both water and salt studies show that salt stress will reduce or halt cell growth in plants.

Can You Save Your Grass If It Is Already Drying Out?

Your grass is resilient and generally hard to kill, therefore, it will take a while for the salt concentrations to have any permanent effect. Thus, if acted quickly, there might be a possibility to reverse the effects.

The trick is to bring down the level of salt, which can be accomplished by simply adding water. The water will dissolve the salt left in the soil and spread it around or even wash it away.

How much water you might ask? That's hard to say, depending on the size of your brine tank, the salt concentration, and the area of grass. The more salt on a smaller patch the more dilution you'll need.

Odds are a simple rain shower will do, but if you're unsure, just keep in mind to spread out the backwash over the largest area possible and to thoroughly rinse your lawn with water if there are long periods without rain or as soon as any dry patches start to appear.

Is Softened Water Bad For Grass?

No, soft water will not hurt your grass. Although softened water often contains salt, generally the concentrations are so low they are nowhere near anything that will damage your grass. Regardless, if you are using a water softener on site you would want to avoid using the water from your water softener.

The sheer volume needed for watering your lawn will use up a huge capacity of your water softener system, thereby wasting the salt that is used to recharge the system and possibly reducing the effectiveness of your system to soften water that is used elsewhere.

If your water softener doesn't have any draining system in place and you are using water softener discharge to water your lawn you're just putting yourself into a vicious circle.

As you decrease the salt concentration in the soil of your lawn, you will use up your water softeners capacity which will, in turn, have to produce more backwash thereby increasing the salt concentration of your lawn as you use it to water your grass.

Using Potassium Instead Of Sodium Could Benefit Your Lawn

To avoid having to deal with high concentrations of toxic sodium you could consider switching to using potassium to recharge your system.

Instead of harming your grass, potassium is often used as a fertilizer and could enhance the health of your lawn. However, again like with normal water softener salt, too high concentrations will kill your grass.

How To Avoid Damage To Your Lawn

To avoid your water softener discharge from damaging or killing your grass, be sure to properly dilute the backwash to lower the salt concentration. Spread it out over larger areas, the bigger, the better.

Alternatively there are grass types and plants that thrive in salt rich environments.