RO/DI wastewater
 

Hello! I just got an aquasafe RO/DI unit..... I just hooked it up to test the TDS and both wastewater and good water outputs show zero on the TDS meter.... So I tested it again afte 2 days, both still measures zero.

Does that mean I can put my waste water into the tank too? The TDS off my tap is about 60ppm. Can someone help? Thanks in advance.

That's impossible. You're doing something wrong. The TDS of the wastewater WILL be higher than the TDS of your tap water.

Yeah I thought so too.... and another thing is I took off the RO and only using 3 stage filtration (5-micron => Carbon block => DI) and the TDS turns out zero as well...... so now I really don't know what to do.....

I would go check something that you know can't be zero. Like your tap water. If it is zero as well then it sounds like your meter is shot. My wastewater is through the roof.

yeah I tested my tap and it reads 60...... I use milwaukee TDS meter btw.

what do you mean you took off the RO? those 3 filters your using make up your RO unit.

Doesn't make sense to me either. I just checked mine,
tap 119
ro/di 0
waste 279

Well, that's odd. The DI resin should only be able to handle 40 ppm, and I don't think the carbon would take out 20 ppm...maybe though. Don't do that too much though because your DI will wear out real quick with that high TDS going to it.

When you test the water (whichever water it is), are you filling a small glass, and testing from the glass or just holding it in the water stream?

Ok, try this. Hook everything up the way it's supposed to be. In one sitting, retest the tap water. Turn the RO/DI on. Let it run for about 1/2 litre (about 4 cups) of product water. Turn it off, unhook the hose after the carbon. Turn it back on and catch the water coming out of there immediately. Test that water. Turn it off, hook up that last hose and unhook it after the RO cartridge. Turn the unit back on, and let it run for about 5 mins. Then catch the (good) water coming out of there and test it. Catch the waste water and test that too. Then hook it back up, let it run for 5 mins, and catch the final product water after the DI. Test that. Report your numbers here. :)

If you lived closer I would bring my TDS meter over and help you out.

You can detach the hoses, and test the water before it enters each stage. What he did though, is removed the RO membrane, and tested the water after it ran through the others.

Sorry I meant I took off my RO membrane.

I filled up one full glass for the TDS meter.... I will try the method you suggested tho, thank you! I live in mountain area in Taiwan btw.... I think our area is very close to the dam that supplies water to Taipei city (TDS is more than 200ppm in Taipei city)... maybe that's why the water is very easy to be filtered out in my area? Anyways....