Water softener drain line tolerance

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Hi all,

I’ve read a lot on these forums and learned a ton. Thanks to all of you for that. I want to bounce a water softener drain line issue off of you all.

I have a GE water softener in my basement. My current drain line runs to my sump pit, and I want to fix that. My manual says that if my water pressure runs between 20-50 psi, I can raise my drain line 8’ from the floor. Over 50 psi, and I can reach up to 14’ I measured my pressure at about 50psi in my first floor utility sink. I have no floor drains in the basement, and I am on a septic.

I can run my drain line up just under 8 feet off of my floor, and run horizontally about 26 feet until I turn to where I can make punch out through the house and drain into my sump pump discharge line which runs underground away from my house. With the water pressure that I have, I don’t think that I will have an issue with back pressure in the drain line. Do others agree?

Second, for installation, could I use braided vinyl pvc and lasso the discharge line to my sump pump drain line until I reach the punch out? I could use zip ties to attach the lines together.

Third, my discharge line is 3/8 ID at the water softener. Some folks have written that expanding the line would be beneficial to reduce back pressure. For example, I could run a few feet of 3/8 ID, then jump to 1/2 and then 3/4. Once the 3/4 exits the house, I would angle it down towards the underground line to ward off freezing.

Do others think this would work OK? Or am I off my rocker today?

 

[ditttohead]

Larger drain line is preferred, you should be ok.

 

[Sponsor]

 

[Eric Wesson]

32 feet is 14.7 psi

I believe the only problem with the line going up is it changes the gpm of the venturi that sucks brine out of the tank. If you put 5 psi back pressure on the drain line, and the supply pressure is 50 psi, you've effectively dropped the pressure across the venturi by 10%. You'll draw brine slower, probably less than 10% slower. Not a huge difference. I believe the concentration of brine (diluted by the venturi water) in the resin bed would remain the same, so it's just a matter of the brine draw taking longer.

My drain line goes up to the second story laundry room. I tested the brine draw rate and found it was on spec despite the drain going up ~10 feet.

Note if the tube goes up and comes back down, the net effect is zero, assuming the tube is not so large that air goes back up the tube.

If the tube is too narrow, you might reduce backwash and rapid rinse flow rates, especially if it has a long run. No harm in using a larger pipe. You can check the pressure drop for your number of feet using online engineering calculators; the max flow will typically be about 3-5 gpm. Off the top of my head, 1/2" ID should be fine.