In tablet form, our products are considered shelf stable (or safe to use) for years. They may lose scent over time, or accumulate moisture beads if left in a humid location, but they’re still safe to use in either case.
Once the tablets have been mixed with water, we recommend using and/or refilling within 6 months.
When we talk about shelf-stability for our All-Purpose Cleaner or Foaming Hand Soap, we’re referring to it mostly in the liquid state - after the tablets have been mixed with water to create a liquid solution. In their solid form, these tablets are shelf stable for years. They may not smell as strong over time, as our essential oil-based scents tend to mellow after a while, but they’re still perfectly safe.
We don't use a preservative, so it is important to understand how long the mixed liquid product can last before that microbial growth begins. Any time you add water to something, you have to consider microbes that could develop and cause bacterial/mold problems within the product. Our All-Purpose Cleaner has been tested for shelf stability for six months without microbial buildup. After six months, we recommend dumping the unused product, rinsing out the bottle, and starting with a fresh batch.
Technical Information on Shelf Stability
When lab testing our cleaning products for shelf stability, we’re assessing the length of time our products can be left on the shelf, counter, or other places in your home before the product expires. Such expiration may be due to poor product performance or microbial growth.
Soap creates an inhospitable environment for microbial growth because of its higher pH (9-10). Products containing a higher pH have been identified as low risk by the International Organization for Standardization (ISO).
Once added to water, there is little change to the pH. However, there is an increased likelihood of microbial growth over time, as microorganisms depend on water for growth. For this reason you will see preservatives in liquid soaps on your store shelves. This ensures the microbes don’t take advantage of the conditions and multiply before the customer can reasonably deplete the product.
As microbiologist Dave Shumaker says, "You need to make sure that microbes won't take advantage of the situation and proliferate.”
When stored correctly, soap-based tablets are not at high risk of microbial growth due to their lack of liquid content. This means you have more preservative-free storage time before use. Once the tablet has been added to water, the likelihood of microbial growth increases over time. Our tablet products were lab tested up to 6 months of use after mixing with water. After that, we recommend starting over with fresh water and a new tablet.