Can I use the Pure-Castile Soap with hard water?Updated 2 hours ago

While you can use hard water to dilute our Pure-Castile Liquid Soap, it may cause your dilution to turn murky or opaque, and you might experience some separation. However, this doesn't impact the efficacy of your soap.

When you combine hard water, or even soft water, with any true soap (not synthetic detergent-based soaps), it can also leave behind a thin film of minerals, also known as “soap scum.” Hard water contains dissolved minerals, primarily calcium and magnesium. All true soaps, such as our Pure-Castile Soap, will react with these minerals to form insoluble stearates, which are visible as a whitish precipitate. This can slightly affect foaming or lather and may leave soap scum on surfaces.

The whitish precipitate may accumulate primarily on surfaces where water is left to dry, such as sinks and showers. However, it's typically not an issue on floors, counters, or other hard surfaces where our Magic Soap is diluted for cleaning and standing water is mopped or wiped up.

Although you can dilute our Pure-Castile Liquid soap, it's not necessary for all uses and mostly comes down to preference. You may prefer to pour just a few drops into your hands for handwashing, while others may prefer to dilute our soap at a 1:3 ratio in a foaming pump. It's up to you!

If you'd like to dilute our soap, we encourage you to dilute only a portion that will be used up within 2 weeks to a month, since we do not add any harsh preservatives to our products that would allow them to last longer than 1 month after dilution. We also don't recommend using our soap in traditional pump dispensers as they tend to clog. Instead, try out a foaming pump.

For more information on using our soaps in hard water, we encourage you to check out Lisa Bronner's blog post The Chemistry of Water and Using Soap to Test for Hard Water.