Connecting a washing machine to a softened water supply

Plumbing-in-washer Should you connect your washing machine to a softened water supply? Before answering this question I need to point out that there are two different ways to soften the water supplied to a washing machine.

One is through electronic devices attached to the outside of plumbing pipes (the effectiveness of which is often disputed)..

The other is a full softening system using chemicals, which as far as I know is less common in the UK than in other countries such as the US).

Some washing machine manufacturers advise against connecting their washing machine to an full artificially softened water supply (not the electronic water "conditioners" mentioned above) as it can make the water too soft for washing. If you don't reduce the amount of detergent it can result in over-foaming, but less detergent can give poorer wash results.

So modern washing machine detergents can be less effective in very soft water because the detergent does not dissolve as well. This can cause detergent deposits on laundry.

Using a washing machine with an artificially softened water supply should not damage the washing machine, but wash results can be affected due to the detergent not dissolving properly and leaving detergent residue on laundry.

This may be counteracted a little by using an extra rinse option on the washing machine if available. This advice may also help If you live in a (naturally) very soft water area.

My current understanding is that this advice is relevant to chemically softened water rather than electronically conditioned devices mentioned above.

These claim to condition the water and prevent limescale build up rather than physically soften water.

Related: Should I use Calgon anti limescale tablets or other such products?

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15 thoughts on “Connecting a washing machine to a softened water supply”

  1. Andy Trigg (Whitegoodshelp)

    Hello Rob, it could be detergent residue as detergent doesn’t dissolve easily in very soft water. Make sure you reduce the amount of detergent used to that recommended for soft water. You could also try selecting extra rinse option if available or making sure you don’t use eco wash cycles that might use less water and make rinsing less effective. As a last resort you could try doing a few extra rinses.

  2. Alex- thanks for the chemistry input. I have that precise type of ion exchange- which removes pretty much all minerals (because I need to remove iron). The problem is ever since the filter, the clothes are getting ruined. I have since turned off the polyphosphate additive, knowing this is a ‘sequesterer’ of what, i’m not sure, but the purpose is to deposit scale on pipes to avoid corrosion.
    My laundry is better, fewer tears, but things are stretched and weak. I have now just started adding magnesium sulfate and by gosh I see a difference. They come out less crunched (wrinkled absurdly) and feel a tad bit sturdier. I want to also try calcite- so basically I am trying to turn the water into what it was before, less the iron.
    I am also assuming the calcite (gypsum) will absorb some of those excess salts, which may be softening my fabrics too much. Do you think this last one will be a mistake? (calcite) I don’t want calcium deposits or anything that will damage the washing machine. I just want balanced water.
    I finally did find some research stating that these precise minerals are used in the industry to give body and stability to fabrics. Just what they need to endure the spin cycle.
    I have yet to try re-shrinking those stretched out lifeless clothes with hot water and a hair dryer / or pellet stove. I’m afraid IT will stress the fibers. Will have to test. As it is my sleeves are well over my hands and sweaters are limp and baggie, PEOPLE ARE OUT OF THEIR MINDS TO WANT SOFT CLOTHES- SOFT WATER !!!!!!!
    (thanks to whitegoodshelp for these helpful articles/comments)

  3. Andy Trigg (Whitegoodshelp)

    Thanks Kathi. And thanks also to Alex’s comment from a few years back. It looks like I might have missed it before.

  4. Just had new machine & dishwasher put in but the kitchen fitter didn’t connect them through the new Softner seen limescale build up in dishwasher already so do I use Calgon or get it connected to Softner? Don’t want my machines ruined as really hard water here in herts! Our last water Softner was used with machines & no limescale problem?

  5. Andy Trigg (Whitegoodshelp)

    Hello S. I have a separate article linked to at the end of this article, which you should read. Essentially if you use the right amount of detergent and ensure that is good quality detergent then you should not need any other water softener. It might not hurt to use Calgon. If you do use Calgon you are supposed to reduce the amount of normal detergent to the dose for soft water. As far as I can see it’s the main function of Calgon because essentially it is only doing what the detergent already does. So the main point of using Calgon as far as I’ve been able to work out, is so that you can use less detergent. I’m unsure if the combination of limescale tablets and less detergent would be cheaper or more expensive than using the highest dose of detergent for hard water or not. Probably not is my guess but I don’t know if anyone’s ever worked out the maths.

    Here is the article, Is Calgon Worth Using?

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