RO product water TDS higher with new filters


New member
I live on a well and had to chlorinate my well due to bacteria found in a water test. I took my filters all out and ran chlorine water all through my RO system to kill any bacteria. After that I drained the unit and actually washed with soap inside and out because I am adding a drinking water system with my RO unit. I have added an auto flush kit to my system as I already had to have a booster pump added to the system. My output TDS is now double of what it was before. Previous I had the BRS 150gpd setup which had two 75gpd membranes with a 550 flow restrictor and it produced 10tds water easily before DI. I increased my new membranes to dual 100gpd and an 800 auto flush flow restrictor. Now I'm getting anywhere between 20-30 TDS before my DI stage.

My system is plumbed bas follows.
Booster pump > inline pressure gauge > TDS meter > valve > 5 micron sediment filter > 1 micron sediment filter > .2 micron carbon block > RO membrane which has the waste of one membrane as the source of the second membrane. Then onto the pressure shut off switch for booster pump > Y splitter. Then either onto the DI canister or through a check valve to drinking water pressure tank.

Is the increase in TDS from my auto flush? New RO membranes? I did flush out the first xx gallons just to clear out any lines of yucky water.


Plumbing Engineer
You killed your RO membrane, they should never see chlorine. you also added soap to the interior of the chambers.

You will at minimum need all new filters and will have to soak and rinse all the chambers you cleaned with soap.

Also whats your incoming TDS? 10 coming out of the RO seems very high.


Active member
An RO membrane is supposed to stop bacteria from what I have read. I would not take my word on that. Residual bleach and soap from cleaning could possibly case problems. If you ringed everything throughly and air dried until there was no bleach smell it should be ok. Also 100 gallon per day membranes usually have higher TDS coming out as they usually rated at 96%, a lower rejection ration rate than the 98% of most 75 GPD ones.


I was going to post some advice but he hasn't been back on to see the other answers so guess he solved his problem.