Water Marks, why are they appearing when my TDS is 0?

Water Marks, why are they appearing when my TDS is 0?

Wed 11 Mar 2020

Water marks, the main thing that any pure-water cleaner doesn’t want to hear from a customer after completing a job. What can the cause be, especially when you made absolute sure your water was pure and measuring 0 TDS.  The good news is this is easily rectified with very little effort.

0 TDS means that there are no solids dissolved in the water, so if your water is measuring 0 TDS before dispensing, then the impurities causing water marks are being introduced at any point after the water has been dispensed. 

For window cleaners, the most likely problem is that the water is picking up the impurities in the window frames, fascia’s and soffits when they’re being hit by the water. The window frames may even be contaminated with soap residue, especially if they have been cleaned by traditional methods in the past. Being filtered to such a high level, the water is far more susceptible to picking up these impurities. Aluminium frames are particularly prone to this, as these can oxidise over time, the residue of which will be picked up by the pure water. Obviously, these are all difficult hazards to avoid, so the best way to avoid this is to thoroughly rinse the window at the end of the clean.