Never store electrodes in deionized or distilled water, as this is the complete solution (3M KCL) migration from the electrode, reducing the hydrogen ion response.
Storage of electrodes:
Storage between measurements
The electrode should be left around the lab, do not store in distilled water.
short term storage
Immerse the tip of the pH electrode in the electrode storage solution (3 M KCL buffer solution/saturated KCL/pH 04.00). Do not allow a solution to evaporate and crystallize on the electrode.
long term storage
Electrode tip caps with safety cap.