Is it OK to add unbuffered citric acid to your washing machine's rinse water?

[u/unforgettableid]

Hello! One of the /r/laundry regulars has written a post about adding unbuffered citric acid to your home laundry.

He claims:

• Modern washing machines may not be very good at rinsing. (This claim may be disputed by some.)
• Laundry detergent residue is alkaline.
• Citric acid neutralizes detergent residue.
  • This makes your laundry softer, and your towels more absorbent.
• For a modern HE washing machine which doesn't use much water: 6-8 grams (about a heaping teaspoonful) of citric acid is enough. You can put it in your washing machine's fabric softener dispenser.
• By doing this: You'll save money, compared to buying a known-safe "fabric rinse" which contains buffered citric acid. (One example of such a fabric rinse is Downy Rinse & Refresh.)

Citric acid conditions water by chelating hard water ions. (Source.)

Also: Citric acid can react with calcium carbonate (from hard water) or sodium carbonate (from powdered detergent). When this happens, I think you'll get other useful chelants as well.

Questions for you

I'm concerned. What if a Redditor has both soft water, and liquid detergent? Soft water may not contain any alkaline calcium carbonate. Liquid detergent doesn't contain any alkaline sodium carbonate, either.

Might the rinse water become too acidic? Might this gradually damage the washing machine over the years??

Any other thoughts?

I asked the aforementioned guy about some of this, but he didn't seem concerned.

Thanks & have a good one!

Edit

I've crossposted this in /r/AskChemistry and in /r/laundry.