We recommend using water which is distilled or purified by reverse osmosis or a system such as MilliQ or Elga, which reduces the amount of bacteria in the water.
It is not necessary to use sterile water, or to store the distilled water in a sterile environment.
While the 1X wash solution will not be sterile in these conditions, its low level of bacteria will not affect results.

A high level of bacteria in the water, however, caused by the progressive contamination of the wash solution or the use of dirty glassware, can lower the quality of the test.

In this case, you will notice a reduction in the difference between the positive and negative signals, and an increase in the background signal.

Generally, it is recommended that the 1X wash solution be prepared at the beginning of the week, and not be kept for more than 5 days (ex. from Monday to Friday).
When making new 1X solution, it is important to wash the glassware and to rinse the wash system (manual or automatic).