tds levels for top off h2o

[cooper]

Folks:

Am awaiting new filters, etc for RO/DI. Right now, my TDS is at 28. How high can I go before I have to worry?

TIA

 

[tony_caliente]

I would start worrying. Should be zero after the DI to the DT.

 

[kirru]

1 your filters are starting to lose their edge, where your at... you are way over due. but i went with high TDS reading for over a year and nothing was wrong, but i also didn't realize that my RO membrane was crap and needed to be replaced sooo that was a PITA..

 

[tgray3]

I'd find someone to help you out with water 'till your new filters come in. My unfiltered tap water reads between 28 and 35.

 

[schwaggs]

I agree, 28 is WAY too high for the output of the RO stage and as mentioned, the output from the DI stage should be 0.

 

[cooper]

thanks folks. I had not seen any changes in the tank...probably why I slacked off on the checking.

 

[jennm]

What's the TDS of your source water?

And are you testing your product water right out of the unit, or taking it out of a reservoir to test it?

I have a customer who had me test his TDS on water collected out of his Brute - it was 20 (incoming was 40)... I then had him collect a sample right out of the output tube of the RO and it was 0. Since he'd just replaced all his cartridges AND the membrane, I knew something was up with that 20.

The barrel likely had dust or bacterial film or other flotsam that just occurs from exposure to the environment.

Jenn

 

[lifestudent]

I don't start replacing filters, DI resin or membranes until my TDS hit 7. Any readings below 7 I find acceptable.

 

[lifestudent]

JennM;532902 wrote: What's the TDS of your source water?

And are you testing your product water right out of the unit, or taking it out of a reservoir to test it?

I have a customer who had me test his TDS on water collected out of his Brute - it was 20 (incoming was 40)... I then had him collect a sample right out of the output tube of the RO and it was 0....
Jenn

Great point Jenn!

Folks really do need to get their sample straight from the output tube into a clean container or have an in-line TDS meter.

 

[cooper]

I have the air, water, ice home unit that stores the filtered water in a 2.5 gallon container. The water I use comes from that container, and it is pressurized so that I don't think it will have any troubles with junk getting into it. I pulled out a filter last night and it was loaded with crap. It's probably been about six months since I last changed the filters. I am calling those guys this morning to see when I last ordered filters and take it from there. Again, thanks folks for your prompt and helpful responses.

 

[jennm]

A lot depends on your source water. I was taught that the RO should remove 85% of impurities or better. So if source water TDS is 100, product water should be 15 or less.

If your source water has a higher TDS, you should probably change your prefilters (sediment and carbon - the stages that the water goes through *before* reaching the membrane) more frequently. Dirty prefilters allow more to reach the membrane, and exhaust it more quickly.

The little bit of money it costs to change those prefilters regularly, will save you in the long run, with a longer lifespan of the membrane, which is the most expensive component to replace.

Example - Last week I had a customer call us about her RO... we replaced her membranes at the same time we last replaced ours. Her unit wasn't producing much (clogged). Her membranes are exhausted. Her TDS and ours (source) is pretty similar, but we have changed our prefilters a number of times, and she hadn't. Result... we just replaced her membranes again. Hers went bad way sooner than they should have because she didn't take the time to replace the prefilters. They were muddy - literally.

An ounce of prevention really is worth a pound of cure.

Jenn