RO Filter and Water Analysis Questions

Hello all.

So I'm close to purchasing an RO water filter system for my house. Once I purchase one and use it for the first time, should I still have my water sent out for analysis (Ward Labs) before brewing with the RO water? If not, when using Bru 'n Water or the Brewer's Friend water calculator, should I input all zeros for my source water? Regardless, I'm going to purchase a TDS meter to make sure that the filter is functioning properly after installation.

As always, thanks for the help.

If you purchase a good highly rated RO system and flush the system per the instructions, you should not have to send the water out to Ward Labs as long as the TDS meter is reporting very low numbers, the system should be working and your numbers should be close to, if not at, zero.

On Bru'N Water, you can enter all zeros for source water (except for pH) or just on the water adjustment section set dilution water to RO and dilution percentage to 100%.

I bought an RO system and sent the water out for testing. I was just curious. Don't waste your money. Most things were 1 or 2 ppm. IIRC, The highest value was 4 ppm.

If I remember, I'll look at it again tonight.

RO water quality isn't usually zeros. That process removes most, not all of the constituents. If your tap water quality is lightly mineralized, the RO water content will be very low. If the tap water is highly mineralized, the RO water content will be higher.

Do remember that RO machines do eventually fail. You need to check your RO water with a TDS meter to assure that the quality is good (low TDS). Get that meter!

mabrungard said:

RO water quality isn't usually zeros. That process removes most, not all of the constituents. If your tap water quality is lightly mineralized, the RO water content will be very low. If the tap water is highly mineralized, the RO water content will be higher.

Do remember that RO machines do eventually fail. You need to check your RO water with a TDS meter to assure that the quality is good (low TDS). Get that meter!

Click to expand...

Martin,

What would you suggest someone enter as their source water values when using an RO filter? And I'm definitely buying a TDS meter so I'll be certain that the filter is truly working

jpb2716 said:

Martin,

What would you suggest someone enter as their source water values when using an RO filter?

Click to expand...

There is an estimate of RO water quality provided as the RO water profile that is loaded in the Bru'n Water software. Depending on the raw water quality, the ionic concentrations could vary by a few ppm.

mabrungard said:

There is an estimate of RO water quality provided as the RO water profile that is loaded in the Bru'n Water software. Depending on the raw water quality, the ionic concentrations could vary by a few ppm.

Click to expand...

Thanks Martin. I appreciate the help. I didn't realize that there was an RO water profile included in your software.

I finally remembered to look at the Wards Lab report I got after I installed my RO system. This is what I got:



When I check the RO water with my TDS meter I usually get 7-12 ppm. Untreated water is usually around 250 ppm.

My raw water is typically around 600 ppm TDS and the treated RO TDS is often between 20 and 40 ppm. As you can see from the report above, 20 ppm reported TDS translates to pretty darn low concentrations for the various ions.

I just used my new RO filter for the first time. My raw water measured 122 TDS and the filtered water read 5 TDS. I'm surprised it got down that low. My tap water pH is typically 8.2-8.5. My RO water is reading 7 pH. I expected lower. Should I be concerned?

jpb2716 said:

I just used my new RO filter for the first time. My raw water measured 122 TDS and the filtered water read 5.I'm surprised it got down that low.TDS.

Click to expand...

That's 96% rejection. Pretty good I'd say.

jpb2716 said:

My tap water pH is typically 8.2-8.5. My RO water is reading 7 pH. I expected lower. Should I be concerned?

Click to expand...

No. Why would you expect lower?

ajdelange said:

No. Why would you expect lower?

Click to expand...

I read that RO water pH is usually in the 5-6 range. That's why I questioned it.

I filtered water for another batch last night. TDS was 4ppm and the pH was 6.7.

Pure water in equilibrium with 0.0003 atm partial pressure of CO2 will be at pH 5.64 but RO water with even a tiny amount of bicarbonate in it will be at appreciably higher pH. For example, 1.5 mg/L bicarbonate is enough to explain your observed pH of 6.7.

mabrungard said:

My raw water is typically around 600 ppm TDS and the treated RO TDS is often between 20 and 40 ppm. As you can see from the report above, 20 ppm reported TDS translates to pretty darn low concentrations for the various ions.

Click to expand...

Since my RO filter is filtering down to 4ppm TDS, would you still suggest I used your RO water profile on your spreadsheet even though that will start me off with higher than 4ppm TDS? Do you have another suggested start point since I'm starting with such a low TDS? Thanks again.

4 ppm indicates that there is virtually nothing in the water. A better option might be to use the distilled profile since that is zero ppm TDS.

mabrungard said:

4 ppm indicates that there is virtually nothing in the water. A better option might be to use the distilled profile since that is zero ppm TDS.

Click to expand...

Thanks Martin. I appreciate it.

Just happy I live in the mountains, the water here is awesome straight out of the tap, All I have to do is just remove the chlorine


pH 7.7
Total Dissolved Solids (TDS) Est, ppm 49
Electrical Conductivity, mmho/cm 0.08
Cations / Anions, me/L 0.8 / 0.6

Sodium, Na 14
Potassium, K < 1
Calcium, Ca 2
Magnesium, Mg < 1
Total Hardness, CaCO3 9
Nitrate, NO3-N 0.1 (SAFE)
Sulfate, SO4-S 1
Chloride, Cl 3
Carbonate, CO3 < 1
Bicarbonate, HCO3 29
Total Alkalinity, CaCO3 23
Total Phosphorus, P 0.64
Total Iron, Fe < 0.01