TDS Report from Water District

jhatfield · May 23, 2016

I don't have a handheld TDS meter at the moment so I was looking over the report from the water district which says that "Secondary MCL" TDS is 1000, Surface Water Average is 700. Any idea which of those represents the water out of the tap?

FYI, The TDS out of the RO runs around 15 and 0 from the DI. I'm assuming with high TDS the life of the RO membrane and the DI is shortened.

AZDesertRat · May 23, 2016

Temporarily disconnect the OUT inline TDS meter tee with the probe still in it. Cut a couple inch long piece of 1/4" tubing, stick it in the out side of the OUT probe, disconnect your tap water line at the sediment filter, slip the TDS meter in and run the system to get a tap TDS. Once you are done move it back to the RO/DI side.

Randy Holmes-Farley · May 23, 2016

jhatfield said:
I don't have a handheld TDS meter at the moment so I was looking over the report from the water district which says that "Secondary MCL" TDS is 1000, Surface Water Average is 700. Any idea which of those represents the water out of the tap?

FYI, The TDS out of the RO runs around 15 and 0 from the DI. I'm assuming with high TDS the life of the RO membrane and the DI is shortened.

The MCl stands for the maximum allowable limit for the item. So that 1000 ppm TDS is the limit, not a measurement. The 700 ppm sounds like an average measurement in your area.