Article - Why you should pre-dissolve your laundry powder if you have 'hard' water

Why you should pre-dissolve your laundry powder if you have 'hard' water

‘Hard’ and ‘soft’ water are words used to describe the amount of minerals (usually calcium and magnesium) present in water. Hard water has more of these minerals and soft water has less, but what does that have to do with your laundry powder?

If you live in an area that’s known to have hard water - like Wanganui, Gisborne, Palmerston North or Wairoa - then it’s a good idea to pre-dissolve your laundry powder before adding it to your wash. That’s because water has a ‘saturation point’. If you imagine adding spoonfuls of sugar to a hot cup of tea, it’ll dissolve easily up to a certain point, (the saturation point) but once you’ve reached that point the sugar will sink undissolved into the bottom of your cup.

Hard water is a bit like sugar-filled tea. It already contains a higher number of mineral particles which means it won’t be able to dissolve as much laundry powder as soft water.

Soft water washes better
Laundry powders contain chemicals (builders) to counteract the hardness of water by removing hard water ions like calcium and magnesium from your wash, which is a good idea because they can bind to the surfactants in your detergent instead of allowing the surfactant to bind to the dirt on your laundry and remove it, resulting in poor cleaning performance. Hard water ions can also react to form scale in your machine if they’re not removed.

Phosphates are often added to laundry powder to make them work better in hard water areas, but disposal of wastewater containing phosphorus is wasteful and can lead to eutrophication - an over-growth of aquatic vegetation which is a huge concern for our aquatic ecosystems.

How do you know if you have hard water in your area?

  1. White deposits around your taps and drains
  2. A ring around your bath tub
  3. If in doubt contact your local water authority or supplier

Tips for hard water

  1. A screw top container next to the washing machine is very handy for pre-dissolving your laundry powder before adding it to your machine.
  2. Hot or warm water has a higher saturation point than cold water does so, dissolving your laundry powder in a jar of hot water is quicker and is more effective.
  3. Check the label of your laundry detergent to make sure it’s phosphate-free. Sodium Carbonate and Sodium Citrate are both just as effective and don’t cause the same problems in our waterways.

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Comments | 1

  • photo
    Hi Mel

    Just moved to a hard water area, and was going to ask re the dishwasher. I have a problem with a white greasy deposit that accumulates over a few weeks on the floor of the machine. I thought the Ecostore automatic powder might not be able to cope with the hard water so have tried adding more than I normally do, but so far no noticeable change. I guess I cannot pre dissolve the powder! Any suggestions?

    I will try pre-dissolving the laundry powder, but I have not had any problems, except I wonder if the cotton bath towels are stiffer than they used to be.


    By Celia Wilson on Fri May 01, 2015

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