Ok so with this post i want to create an FAQ which we can refer to for new window cleaners. So what i would like is for you lovely members to post what you think should be on the FAQ for new members. Post your reply like this. Q. What is a TDS meter? A. A TDS Meter indicates the Total Dissolved Solids (TDS) of a solution, i.e. the concentration of dissolved solids in it. Since dissolved ionized solids such as salts and minerals increase the conductivity of a solution, a TDS meter measures the conductivity of the solution and estimates the TDS from that. For window cleaning this indicates the purity of your water. What i will then do is gradually add your replies to our FAQ page to hopefully create a very helpful page to answer those newbie questions.