Understanding Total Dissolved Solids
Not all potable water is created equal or in other words has the exact chemical characterization. But variations in potable water quality may not impact ice clarity as claimed by others. Potable water is defined as drinking water that meets state and federal standards and guidelines for consumption. Water produced as an ingredient will often have specific water quality characteristics to create a consistent flavor (think of global soft drinks and coffee shops). An aesthetic or “secondary” standard often used to describe water is total dissolved solids (TDS), a measure of constituents that are dissolved in water. Excessive TDS can cause hardness, mineral scale, and affect the taste of water. Below is a range of Total Dissolved Solids in various water sources.
image credit - Premier Water Technologies
- Ice making in industry (ice distributors, bars, restaurants etc.) will typically treat their water with Reverse Osmosis (RO) to get below 50ppm of TDS
- Ice making at home can use a wide range of water sources
- Homes in major metropolitan areas get tap water with 100-300ppm TDS
- Many homes take this tap water and treat it with a carbon filter either integrated with their refrigerator or pitcher to reduce TDS below 100
- A smaller percentage of homes will treat incoming water with reverse osmosis or use bottled water for their ice making needs to achieve less than 50ppm of TDS.
Ice Clarity as a Function of Total Dissolved Solids
The quality of water will impact the impurities and melting speed of the cube but will not have a significant impact on the clarity of the cubes produced despite many clear ice making articles found online.
Many articles claim that either boiling water or making ultra pure water will produce clear cubes. Klaris experiments have demonstrated that this is far from the truth. Clear ice is primarily driven by directional freezing.
To illustrate, food coloring was added to tap water as a visual impurity. This colored water was placed in a simple silicone mold, complex silicone mold and the Klaris ice machine. Normal operating processes were followed for each process and the results can be seen below.
Simple Silicone Mold (Freezing from all sides, no agitation)
- All impurities trapped toward center of the cube
Complex silicone mold (directional freezing, no agitation)
- Impurities pushed to bottom of the mold
- Some impurities caught in the corner of the cubes
Klaris (Directional Freezing and agitation)
- Impurities pool on top of the ice
- No impurities embedded in the cubes
As demonstrated with the Klaris machine, impurities concentrate in the pool of water above the cubes. This pool or residual water is purged at the end of the ice making process. These results are like the complex silicone mold. However the residual pool with the blue impurities actually freezes into the cubes and will require another step to remove.
Directional Freezing as a Purification Process
Early Klaris research and development (R&D) measured TDS (Total Dissolved Solids) of water before and after the Klaris ice making process. Comparing the TDS of the water used to make ice and the residual purge water, directional freezing is proven to be a purification process. There was an increase in concentration of impurities (measured by TDS) in the residual purge water of 40-60%. Proof that a variation in potable water will not improve the clarity of ice but an automated directional freezing process gets the desired results!
For the best clarity, purity and melt rate, we recommend using water with less than 100ppm of TDS combined with Klaris' directional freezing process and active agitation. Stay tuned for more experimentation and results proving why Klaris cubes are better!