TDS over 700 from city water

Joe's Coral Reef · May 13, 2017

I've recently moved into a new place and just connected my ro/di equipment to make water. I made about 30 gallons, then noticed one of the di cartridges turned colors like it was exhausted. I checked the output it was 2 tds, then I check what's coming out of the faucet. My jaw dropped, 760 tds. I have no idea what todo now. Anyone experience high tds on the supply? Suggestions on what I should do?

Coral Addict · May 13, 2017

Start with a booster pump. Do you have a water softner?

KJAG · May 13, 2017

Soften your water at the outlet prior to entry into the unit and make sure you don't plumb your DI to a float valve, as the intermittent daily short cycling through the unit will shorten the life of your DI resin.

Randy Holmes-Farley · May 13, 2017

Did you measure the TDS of the water after the RO and before the DI?

Joe's Coral Reef · May 13, 2017

Coral Addict said:
Start with a booster pump. Do you have a water softner?

Yes I have a booster pump. I also have a water softener.

Joe's Coral Reef · May 13, 2017

Randy Holmes-Farley said:
Did you measure the TDS of the water after the RO and before the DI?

The tds is 68 after the membrane and before the di.

Randy Holmes-Farley · May 13, 2017

Joe's Coral Reef said:
The tds is 68 after the membrane and before the di.

That is pretty high. What type of membrane?

Joe's Coral Reef · May 13, 2017

Randy Holmes-Farley said:
That is pretty high. What type of membrane?

100 GPD Membrane - DOW Filmtec

skim · May 14, 2017

That seems to a bit high, I know it's a 100 gal membrane and with those numbers you are getting about 91%. You say you have a booster pump and run a softener, you may want to check and see if the softener is working properly. During your move the RO membrane may have dried out and is not working properly especially if it has been used for sometime. I would get a new membrane or you may even want to try and move to a 75 gal. Membrane as they are the most efficient and get a new restrictor. This may work much better for you.

Randy Holmes-Farley · May 14, 2017

skim said:
That seems to a bit high, I know it's a 100 gal membrane and with those numbers you are getting about 91%. You say you have a booster pump and run a softener, you may want to check and see if the softener is working properly. During your move the RO membrane may have dried out and is not working properly especially if it has been used for sometime. I would get a new membrane or you may even want to try and move to a 75 gal. Membrane as they are the most efficient and get a new restrictor. This may work much better for you.

Unless hard water damaged the membrane, the softener will, if anything, boost the TDS in the effluent water from the RO. That's doesn't mean it is bad to do (its is good for purposes of preserving the lifetime of the membrane and prevent calcium and magnesium carbonate deposits onto it), but sodium is harder for an RO to reject than is calcium.

AdamNC · May 15, 2017

I had a similar issue when I first moved into my house 6 years ago. I'm the last house on the street and from the house sitting dormant for about 250 days gunked up the water pipes. I had my local fire house flush the lines for an hour on the street and then I ran all my faucets for about 30 mins. Cost me a pretty penny but now I have a fairly decent water supply.

Joe's Coral Reef · May 16, 2017

AdamNC said:
I had a similar issue when I first moved into my house 6 years ago. I'm the last house on the street and from the house sitting dormant for about 250 days gunked up the water pipes. I had my local fire house flush the lines for an hour on the street and then I ran all my faucets for about 30 mins. Cost me a pretty penny but now I have a fairly decent water supply.

Wow, that could be my issue also. My new place has been empty for over a year, before moving in, first thing I did was set up the RO system and started making water. I'm going to run all the faucets tonight for a little while and retest the supply for TDS.

skim · May 16, 2017

You may also want to force a regeneration on the Softener, so it can get a good flush.

Joe's Coral Reef · Jun 3, 2017

So I've talked with the local water filter store and the engineer at the local water department. Water is sourced from a well and treated to remove iron. They don't use chloramine. However it's still very hard, 750 tds is normal, it contains lots of calcium and magnesium.

The tds coming out of my membrane is 40 tds, which if the incoming is 750 tds, the membrane is working. So after calling a few companies they just suggest buying more di,but at at 40 tds, it just chews up the resin.

So I have an idea. If I take the 40 tds water out of the membrane and put it into a storage container, then using a pressure pump, run the 40 tds water back through the ro system, then use the di resin. Would that work? I'd lose some water due to the rejection of the membrane, but I'm wondering if it'd be cheaper then buying di resin constantly.

Randy Holmes-Farley · Jun 3, 2017

That might end up being cheaper if you make a good amount of water.

Cory · Jun 4, 2017

Joe's Coral Reef said:
So I've talked with the local water filter store and the engineer at the local water department. Water is sourced from a well and treated to remove iron. They don't use chloramine. However it's still very hard, 750 tds is normal, it contains lots of calcium and magnesium.

The tds coming out of my membrane is 40 tds, which if the incoming is 750 tds, the membrane is working. So after calling a few companies they just suggest buying more di,but at at 40 tds, it just chews up the resin.

So I have an idea. If I take the 40 tds water out of the membrane and put it into a storage container, then using a pressure pump, run the 40 tds water back through the ro system, then use the di resin. Would that work? I'd lose some water due to the rejection of the membrane, but I'm wondering if it'd be cheaper then buying di resin constantly.

You can also collect rain water and snow. The tds of both is close to zero.

Breadman03 · Jun 4, 2017

Alternatively, you might consider getting one of the high-rejection membranes that Spectrapure offers.

vanpire · Jun 4, 2017

Call Spectrapure. They have a 98% reject membrane. That might help you. If memory serves me correctly, it is about $5-$10 more than the standard membrane.