Bad RO storage tank causing TDS > 0?
 

Bad RO storage tank causing TDS > 0?
TDS before DI is about 3. TDS after DI is 0. But once it goes thru the RO storage tank, it is 5. I flushed it 2-3 times and it is still the same.
This 4 gallon storage tank is a few months old. I doubt if it is getting rusted inside.

https://www.amazon.com/gp/product/B00439MYYE

What to look for when shopping for a new storage tank? Plastic? NSF?
Cheap ones are generally no good? Or they are all made the same way?

If you're only storing 4 gallons why not try a 5 gallon food grade plastic bucket or two? They are very inexpensive. I am assuming your current tank is metal.

The RO system is also used for our drinking and installed under the kitchen sink.
It runs to supply RO for sink dispenser, fridge, instant hot water dispenser and the 4 Gallon storage tank. The storage tank is needed to provide the pressure.

So you run RODI and store it in that tank? I don’t recommend drinking RODI water, it’s not believed to be good for you long term. As for TDS post RODI, I wouldn’t worry if it reads 0 coming out of DI. Dust and other particles in the air can cause TDS to increase. So it’s picking up something.

Even if the container doesn't leach into the water, carbon dioxide will enter RO/DI and raise the TDS over time. 5 ppm is fine for stored RO/DI. I wouldn't worry much, given that the container is intended for drinking water, but you could switch to a food-grade plastic, if you are worried about metal contaminants.

Drinking RO/DI water is fine as long as the microbes are kept under control. I did that for years. I'd be careful with storage for human consumption, though.

The tank should have a bladder made of butyl that holds the water.
Cheers! Mark

My RO system is connected in the same way. I simply turn off the valve on the tank when making water for the aquarium. This way the tank remains full for my use and I don't use the higher TDS water (although, ALL of my water is high TDS). :(

Any RODI water stored will increase in TDS, it doesn't take much to get to 5ppm.
Anything under 20ppm is fine, it's that tap water at 150-400ppm that causes problems..

Now, if that number starts to increase regularly, that should mean filters need changing time...

I guess we have clean water where I live. Incoming is only 4ppm tds

Municipal water coming in at 4ppm, would be by far, the cleanest water I have ever seen anywhere in the world......that's outstanding results.......my compliments to your water people! The EPA has no posting anywhere in North America of TDS results of incoming water that low, but caps TDS at 500.

We have some super treatment facilities in Canada here, but can't touch that. For safety, we included a small amount of disinfectant, (chlorine) and calcium, a few other minerals, so we are mostly in the 140 ish range,


So you don't even need to do RODI....that's not fair!

Any water under 80 TDS is not reccommended for human consumption as it lacks the necessary ions for health

Our water has chloramine. I thought 4tds was an error but a buddy on the other side of town says that's what he is measuring also. The 4 is right before the DI if that makes a difference?

Sorry, when I referred to "incoming water" I was talking about city/state treated, glacier/lake/stream fed or well water to your tap. In these cases, the lowest is 50 and the highest could be over 1200. Safe to drink starts at 100 and ends around 300, over this point you should be filtering your drinking water. Average is 140 to say 200.

If you guys are getting 4ppm out if the tap, the meter is broken!
Just the cholamine is more than 4ppm.
Even after RO + DI ranges can be 0-10.
Sounds like you measuring incoming after maybe an RO pass...

Water at any TDS is fine to drink if the contents of the water are safe, which generally is true for city drinking water. If you are highly malnourished, then choosing a water source with more mineral content might be appropriate.