Varied TDS Readings
 

I've got a Aqua Safe RO unit that I put some new filters and RO membrane in a couple months ago. I've been testing it out but the TDS readings seem to be all over the place. One batch of water will be 2 and then the next batch will be 40. I don't understand the high readings since normal tap water is only 19 or 20 so how it runs through filters and comes out with a higher TDS reading I don't know. I've got it hooked up to a sink in the basement that is right beside the washer and dryer. Is it possible that other sources like having the washing machine on at the same time is contaminating the water? This might be a stupid question but can the TDS reading climb if the filtered water sits for a period of time? Thanks for your help.

yes actually mine comes out at 750-800 PPm from the tap :redface: when the RO/DI s going its at 0-1PPM then after the RO/DI has stopped it will climb up to 50-60

So would you say that's normal or could you be having the same problem?

My guess would be when having the washing machine on at the same time you don't have enough water pressure for the membrane to work efficiently.

The pressure guage still shows 50 to 60 on average.

I believe the membrane is most effcient at 80 psi.

K, so I've tested it over the last 24 hours and the reading is substantially less when its first filtered (2 to 6) than after its sat for 24 hours (30 to 50).

Thats the TDS of your saved water after 24 hours? If that is you have something leaching into the water from water pail you are saving the water in I would guess.

+1

But additionally, you should absolutely be getting 0 TDS coming straight out of the RODI unit. Run the output from the RODI into a clean glass and check the TDS. It sounds like you're getting contamination from your storage vessel.

I just tested it right out of the RO unit and it's reading 6. Could I have installed the RO membrane incorrectly? It didn't look like there's much to screw up in the installation.