Water Purity (TDS 7) and EDTA in Cosmetic Formulation

Hello,

Regarding your question about using purified water with a TDS value of 7 for cosmetics and the need to add EDTA:

• Water with a TDS value below 20 is considered pure enough for cosmetic formulations. Your water with a TDS of 7 is therefore suitable.
• The TDS measurement should be taken on the pure water before adding any ingredients. Adding ingredients like EDTA will increase the TDS value, which is normal and expected, as TDS measures total dissolved solids. The high TDS reading after adding EDTA does not mean the water is no longer suitable; it simply reflects the addition of EDTA.
• Even if the initial water is very pure, adding EDTA (Disodium EDTA) is still recommended. EDTA acts as a chelating agent, helping to bind metal ions that may be present in the water or could potentially dissolve into the water over time from contact with air.
• Adding a small amount of EDTA (like 0.2%) is generally beneficial for the stability of the formulation and is cost-effective.
• The only exception is if your formulation contains Copper Peptide, in which case EDTA should not be used.

Therefore, you can use the pharmacy water directly, and it is recommended to include EDTA in your formulation (unless using Copper Peptide) for added stability, despite the increase in TDS after adding it.

Thank you.