Bleach in prewash calculator

Lately, we’ve been promoting bleach-in-prewash in our Facebook group to help with cost of living pressures. After extensive testing, we’ve concluded adding bleach to prewash is the most economical and effective way to improve your nappy routine.

About this method

This is a regular prewash using detergent and chlorine bleach. The chlorine bleach takes the place of laundry booster.

Using bleach allows you to use a lower water temperature, which reduces energy costs, and saves you money on your power bill. It is also less expensive and more effective than traditional oxygen-based laundry boosters. The amount of bleach is safe to use on nappies and does not cause premature degradation to PUL nappy covers or inserts.

Situations that benefit from bleach in prewash

Consider adding bleach to your prewash if:

  • Your child has extra stainy poos (such as when baby is exclusively breastfed)
  • You store the nappies in a closed bucket or wetbag all-day
  • You want to use night nappies but don’t want to handwash or prewash at 60°C
  • You use a top loader, especially if you have an electric tank hot water system, which takes a long time to reheat. Save the hot water for showers!
  • You need or want to reduce electricity use where possible
  • You want to cut corners with your wash routine but still get reliably clean nappies

Adding bleach to prewash is my number one tip for reliably clean nappies each and every time. It is the easiest, cheapest and most sustainable way to prevent stains, smells and ammonia. This simple addition solves the vast majority of issues that CCN members come to us with.

~ Anastasia, Environmental Scientist and founding Facebook group admin

Read more testimonials.

Washing in cold (or colder) water

With the rising costs of energy, we know our members are looking at ways to reduce their hot water use. Using bleach in your prewash enables you to wash in cooler water.*

Cold (30ºC) water is not as effective at removing stains, so be prepared to pretreat items with bar soap prior to washing them.

* If nappies smell after washing in cold water with bleach increase the water temperature to 40-60ºC.

Using night nappies

Our previous advice was to hot handwash night nappies or add them to a 60ºC, 60+ minute prewash. Adding bleach to your prewash enables you to machine wash your night nappies at a lower temperature. This is great news for top loader owners or anyone who is unable or chooses not to prewash at 60ºC.

About this calculator

This calculator is focused solely on bleach in prewash. We hope this page makes this process more straightforward and a lot less confusing.

Remember, bleach in prewash is not a sanitise, it is to reduce the soiling level or for stain removal. Looking for more stain removal or sanitise options? Our complete list of 31 different options are provided in the full bleach calculator (available to website subscribers and patrons).

Bleach safe items

This concentration is not suitable for non-colourfast items due to the risk of fading and localised bleaching. Non-colourfast items are natural fibers (cotton, hemp, bamboo) that have been dyed or coloured.
This concentration is suitable for nappy covers and other items containing PUL and elastics.
This concentration is suitable for white and colourfast items.

Exclusive Patreon member content


I use chlorine bleach in place of laundry booster. Not only is it cheaper, it is also more effective! It’s removed some long-lasting banana stains from my kids’ clothes and busted smells after nappies have sat in an enclosed bucket all day at ELC.

~ Katie, Facebook group moderator and cloth user of four years

The ‘Bleach in Prewash’ option is such a great addition to my nappy routine, it is cheaper and more efficient than booster was, my nappies and small whites have never been cleaner!

Eloise, Facebook group moderator and cloth user of four years

I use bleach in prewashes, and have done so for some time now. It’s amazing! I used to make it up as I went along (pro tip: don’t do this!), but now I measure out a bit properly and add down the drawer as usual. If I have something coloured or otherwise not bleach-safe, I just skip the bleach that time and add booster instead. It all comes out in the wash, literally and metaphorically 😎

~ Jacqueline, cloth user

I alternate between bleach and vanish in my prewash and it’s game changing. I add an extra rinse to my prewash when I add bleach as I don’t like the smell of bleachy prewashed nappies. I’ve got an old baby bottle that stays in the laundry for bleach measuring.

~ Ayla, cloth user