Water softners and cast iron pipes

Had a thought the other day. Since salt is corrosive, will the brine from a water softner lead to corrosion of a cast iron drain line? Also how about the sodium in the water, does it effect galvanized pipes or is the amount too low to cause issues?

Yes it does, but I feel cast iron and galvanized pipes have all lived past their normal life, so I write them up as Recommending immediate replacement .

There’s nothing immediately wrong with cast iron drain pipes. They are quieter and they are often good for 100 years, which means I’ll get another fifty out of mine.

How misleading.

And Lord forbid you come across modern iron pipe. There is a huge difference in modern cast iron. Older cast iron was sand cast. This manufacturing method was a little less than perfect. The side wall thickness of the pipe could vary and it was possible for pin holes leaks and rust pimples to develop over time as a result of this deficiency. Modern cast iron piping is spun cast. This method creates a sidewall thickness that is very consistent and is virtually defect free.

I see a lot of cast iron, saw some today. I have been told some insurers have not provided coverage due to it, but I think that might be an urban myth.

Anyway I don’t think there is anything inherently wrong with it provided its sound and the joints packed and dry, no cracks. I think you would also find that the horizontal runs (undersides) would be most prone to corrosion particularly if not sloped properly.

That may not be a myth. Last week, I received a call from an insurance agent looking for inspectors to “certify” that plumbing supply and drain lines were copper and pvc respectively in slab homes at 40+ years of age. It was some sort of slab coverage policy.

The only cast iron pipes I call out (needing replacement) are the exposed pipes that are pitting and seeping onto the floor.

Other that that, I’ve seen many cast iron waste lines that are 100 plus years old and could actually last another 100 years.

Just curious, How do you do that? You got a pair of x-ray glasses left over from the 60’s? :smiley: :wink:

Actually I told him that it was virtually impossible to make a determination like that without tearing into the walls, pulling up each and every commode, shower and tub. Oh and jackhammering the slab to pieces.

I politely passed doing the “certifications” by saying that I would not want someone coming back to me for “certifying” those two components were in use only to find out that a hidden portion of old galvanized drain or supply pipe leaked and caused a foundation issue. If the insurance company refused to pay the claim, I certainly didn’t want to be the one left holding the bag. In my opinion there would simply be no defense that one could make. That is about where our conversation ended.

So… do most of you conclude that water softeners can cause a cast iron pipe to corrode faster?

Probably not.
Any byproducts of the softening process(primarily Calcium and Magnesium salts)would be in contact with the cast iron for a short time because the normal waste water in the system would flush it away quickly.


Seeing as most softners timers are set to regenerate in the early hours of the morning, and horizontal runs are not going to be flushed till the residents rise, what makes you so sure that the horizontal runs will not suffer? There are also salts being discharged along with the collect hard water deposits.

Evidence please?

Where’s yours?

I stated “probably” and offered my reasoning. How about you?


Nice try. I explained my theory and rationalize why.

The rest of the story just for you Raymond.

To ensure that no salt brine is released into the home water system the rinse cycle runs for a long enough time to remove any remaining brine in the mineral bed. This cycle is always longer than needed to clear the system of brine, several gallons of fresh(now softened) water are flushed down the drain pipes. No brine is left in the pipes.

Make sense now?

I used to work for what is now Ecowater for over 5 years.;-):wink:

Yes and I am not afraid to admit I was wrong. So I my apologies.

But do you have any proof you worked for who you said you did? :mrgreen:

Raymond it was more than 30 years ago. I don’t keep my W-2s that long!

My father installed softeners for them as a plumber.
I worked my way through college working for them delivering salt and repairing rental units.

I have installed and repaired 4 units in homes I have owned as well as friends.

Hope this helps.:slight_smile:

Four years ago, Mr. James M. Troth posed the original question on this thread: Will the brine from a water softener lead to corrosion of a cast iron drain line? A definitive response has not been offered. I would be very grateful if any plumber could offer more information on this topic. Thank you.

You might try asking your question on a plumbers forum but take a look at this.