RO/DI questions

[Kentanner11]

Ok so as I get closer to buying my RO/DI unit, I have a few questions:
1) Alot of FW forums/people say NOT to use RO or RO/DI water, why is this, and is it true?

2) What is the "waste" water? (Is it drinkable? and why is it considered waste?)

3) I know people have used the "waste" water to fill up their washing machine, and it sounds like a good idea, and will be feasable for me as I hope to mount my RO/DI unit above my washer, anyways how much water can a washer actually hold? (It's not like Im making millions of gallons, but when I start my tank and make like 100+ gals that will be 400+ "waste" gallons)

4) In-line or H.H. TDS meater?

Thanks!

[JeffKirk]

1- Not sure, I've used everything from tap to DI (store bought) and other than more algae w/ tap did'nt notice a difference.

2- Bear Grill drank his pee the other day on the Discovery Channel so Yes its drinkable. I would'nt dare to drink it because it's loaded with all the TDS your R/O membrane took out of the water.

3- You can use it for watering the lawn, washing clothes, cleaning the floor, it's basically Non Potable water.

4- HH TDS meter would be great (I don't have one yet) but am running w/ the dual meter on the MaxCap D2, and the convenience of having it test my output water is unmatched.

[random_ryan]

I got my TDS meter off ebay.

[grenaria]

1) The reason for using RO/DI for salt water is that you have prepared additives that contain ALL of the dissolved ions you want to reproduce (AKA salt mix). For some fresh water tanks, you want to have some ions in the final water, but dont have many premade ion mixes, but they do exist. Another reason is pH and dissolved CO2 and O2, deionized water is a very strong solvent and incapable of supporting life right out of the machine. A small amount of buffer and some aeration solves this for FW, salt and aeration solve it for SW.

2) Waste water is water that is rejected by the RO membrane. Basically it is ~20% concentrated tap water, that has passed through your prefilters. I use it to water plants, as it is free of chlorine (due to carbon prefilter).

3) Different washers hold different amounts, most Energy Star washers hold ~20 gallons, normal washers are ~ 40 gallons. If you really care about saving every gallon of water you could use it to fill a gravity fed cistern, which you could also use to collect rain water.

4) Both. If you don't have inline TDS meters, you will have to install lots of valves or regularly disassemble parts of the machine to get TDS readings after different components. I use my handheld TDS meter all of the time for many differnt purposes; verifying accuracy of in-line meters, making sure bottles are labeled correctly, don't have in-line after final DI stage...

[Kentanner11]

I heard that with the Inline TDS meeters dont factor in temp?

[AZDesertRat]

That is correct. The HM Digital handheld is by far the best investment you can make for TDS testing. Inlines are sensing air temperature and not water temperature so if your air and water are not exactly the same the error can be quite significant. They are great as an indicator but I always pull my handheld out to test and find they never agree since my unit is mounted in my garage and it gets quite warm there.

To answer your other questions,

1. Fresh water tanks are usually pretty hard water and some even border on brackish. RO or RO/DI or even soft water are counter to this.

2. Waste is a relative term. It is actually flush or brine water. All water has passed through a sediment prefilter and carbon so it has been stripped of any suspended solids and chlorine. It has not been treated down to the dissolved solids level though by passing through the membrane or DI resin. It will be about 20 to 25% higher in TDS than tap water as it is concentrated. Remember the 4:1 waste ratio a system has? Well the dissolved solids from that 1 gallon of good water is now mixed in with the 4 gallons of waste making it hagher in TDS. It probably can be consumed but I either run it down the drain or water plants/lawn with it.

3. Putting it in the washer is not an option for me since I make large batches at a time, usually 25 to 50 gallons of RO/DI at a session so I generate way too much waste to contain like that. Plus I don't want all those solids in my laundry anyway. I paid good money for a water softener to extend the life of my plumbing and appliances, why would I put it back in in a concentrated form. Same goes for the "zero waste" systems Watts Premier sells, they dump the waste in your hot water heater shortening its life.

4. See the first paragraph. COM-100 Handheld is my choice.

[Kentanner11]

this tester? I got that from Filter guys. PS OHH a lanyard I can go around testing every ones water! jk! lol!

$50.00 - HM DIGITAL COM-100 TDS METER-WATERPROOF EC /TDS /TEMP COMBO METER

FEATURES
COM 100: WATERPROOF EC / TDS / TEMP COMBO METER
Measures electrical conductivity (EC), total dissolved solids (TDS) and temperature
Three different calibration options (KCl, 442TM, NaCl), each with its own non-linear conversion factor
Automatic Temperature Compensation (ATC) using three temperature coefficients
Waterproof housing
Measurement Range: 0-9990 µS; 0-8560 ppm (auto-ranging)
Digital Calibration (push button)
Auto-off function, data-hold function and low-battery indicator
Display: large and easy-to-read LCD screen includes simultaneous temperature reading
Factory Calibrated: The COM-100 meter is calibrated with a 1413 µS solution. The meter can be recalibrated with digital calibration using the push buttons, rather than a screwdriver
Includes a cap, batteries and lanyard

[AZDesertRat]

Thats the one. You can also get it from Spectrapure and there is a group buy being put together here locally. It can save you quite a bit if you can find someone to pick it up for you since you are down south. I would also look at the MaxCap system if you are looking for a new system, its by far the best available and you can't beat the group buy pricing.