All About Water Discounts

I first mentioned water discounts last week.

It’s considered an advanced technique for soap makers but today I’m going to do my best to explain and simplify the concept.   A water discount is when we deliberately use less water than what the recipe calls for. There are many reasons whey would choose to make a water discount.

A water discount can be a good choice when you have lots of soft oils in your recipe, for example a 100% olive oil soap.  If you’ve every tried using a recipe with a high percentage of soft oil in a multi-cavity silicon mold, you know how frustrating it is to wait more than 48 hours to unmold your soap or to have remove the bars and find that they’re  still sticky or moist, and find their edges soft and ruined with all the pulling and prying. Doing a water discount for your next batch of this recipe would be a good idea. It will allow your bars to harden faster. And this doesn’t just work for multi-cavity molds.  You can also choose to do a water discount if you’re using a single loaf mold.

You might also opt for a water discount if you want your bars ready for use faster. Less water in your soap batch means a less curing time, and a harder bar. (Because there is less water in the recipe that needs to evaporate from the bar for it to harden)

If you’re adding pureed vegetables to your soap, you can use a water discount to account for the water that’s being added by the puree.


Is Water Discounting Dangerous?

Well, yes and no. A water discount means your lye will have less water to be diluted in. Meaning your lye solution will be more concentrated, meaning it will be extremely harmful if it comes in touch with your skin.

However, adding this concentrated lye solution will not make your soap dangerous or ‘lye heavy’. The lye solution still has the correct amount of lye for the saponification process to happen. It is the lye solution that is more concentrated.

Using a water discount will not affect the quality or safety of your soap. It actually has some benefits: First of all, your soap will be less likely to develop soda ash. Another benefit is that you’re less likely to see any glycerin rivers.

The only downside to using a water discount is that your batter will thicken faster. And if you add an essential oil or fragrance that causes yours soap to accelerate faster than you can work, then that would be another challenge. You can still do swirls and layers, but if your fragrances  affect your soap, you might be limited to what you can do.  In this case, it’s always good to have a plan B for your designs, and if you’re planning on more intricate designs, maybe avoid the water discount the first time you try it to give yourself enough time to work with your soap.

Now, most soap calculators calculate the amount of water to be between 33%- 38% of the total oil weight.  And that’s why if you plug in your recipe into different soap calculators, you might get different values for the water.

What’s important to note is that the amount of water is determined by the amount of lye in the recipe. When a soap calculator uses 33%-38% water of the total oil weight, this is usually a 3:1 ratio of water to lye.  (3 parts water : 1 part lye. Meaning that the amount of water is 3 times the amount of lye in the recipe)

When we do a water discount, we are decreasing this ratio. It’s important to  remember that this ratio of water to lye should never go below 1:1. That’s because you need at least equal parts of water and lye to make a lye solution that will saponify the oils. Going lower will than 1:1 will destroy your soap.


When I’m doing a water discount I always go for a 2:1 water to lye ratio, which means I double the amount of lye to get my water weight.

For example if my recipe calls for 50 grams of lye, I’ll use 100 grams of water. (50 x 2= 100)

I don’t recommend that you go for 1:1 ratio. I think it’s too risky.

Remember that going for a water discount will make your lye solution more concentrated and you’ll have to work faster with your soap because it will thicken faster.


Let’s take an example of a recipe that I made today and decided to use a water discount

This is the original recipe

Olive oil  873.16 gm

Argan Oil   249.48 gm

Coconut oil  124.74 gm

Water  474 gm

Lye  166.37 gm


I wanted to make this batch with a water discount so instead of using 474 g of water as the recipe demands, I used double the amount of lye

This will give me a ratio of 2:1. 2 parts water: 1 part lye

So instead of using 474 gm of water, I used 166.37 (the weight of the lye) x 2 = 332.74 gm of water

So my new recipe is

Olive Oil  873.16 gm

Argan Oil 249.48 gm

Coconut Oil  124. 74 gm

Water   332.74 gm

Lye  166.37gm

I followed all the same regular soap instructions to make my soap but this time with a water discount


So why aren’t beginner soap makers taught to do a water discount?

Well, I think for a beginner soap maker there is so much to keep in mind, and you need to work slowly as you get familiar with the soap making process, the tools, and the ingredients.  You NEED the time.  So it’s easier to tell students to follow the recipe given to them by the soap calculator, safer for them to work with a less concentrated lye solution, it gives them more time to work on the process, and it takes a way one extra (optional) step of calculations.

If you’ve been making soap successfully for a few months, I encourage you to try a water discount. I would recommend you get all your ingredients and supplies ready before you start (common soap making sense) and prepare your recipe with the water discount before you begin.


Good luck, and I can’t wait to hear about your creations.

1 comment

  • Thanks for sharing your take on water discounting. I just wanted to share a few comments

    Regarding the recipe given in the article, one of the important skills in creating a recipe that offers a balance of fatty acids to create the best soap qualities, which depends on your choice of oils. All oils have different characteristics and offer something different to a soap recipe. Soap qualities include the hardness of the final bar, its cleansing power, how conditioning it will be for the skin, the amount of bubbles or lather, and its creaminess.

    An important marker of the recipe is the INS value, which is a combination of the iodine and saponification values. The higher the INS value, the harder the soap will be. The INS range should be approximately 130-165 and though you can go higher or lower to experiment, you should work with your recipe to make sure you aren’t making sacrifices on the qualities by choosing oils that push your INR much lower than the recommended range. A low INS will result in a softer bar. Most soapmakers aim for a good hard bar simply because it will last longer – it is less likely to turn into a gooey sort of soap gel when it comes into contact with water (though you should always protect your bar from sitting in water no matter what). The recipe in this article is a bit weak in several soap qualities. I would suggest providing a recipe that is more balanced. Olive oil, argan oil and coconut oil as the full oil content for a soap will offer a high level of conditioning but the coconut amount is rather low and not enough to balance the recipe to achieve the cleansing, creamy and lather qualities most people want in a bar of soap. With the INS for this recipe at 118 the soap will likely be quite soft. Adding a harder oil (palm, as well as a touch of castor oil could help round out this recipe and offer a better balance and would be better for a beginner to work with.


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