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What is the best drinking water system?

by Mark Timmons February 21, 2007 17 Comments

There is no "BEST" filter or system, but there are several questions you should ask yourself to determine which type of system is best for you. There are also some questions you should ask if someone is trying to sell you a water treatment system.


First of all you need to determine why you want a drinking water filtration system. Are you only concerned with aesthetics (taste, odor, etc.), or are you concerned with possible contaminants in the water, which you wish to reduce? These are two very different issues. For example, if you are only concerned with aesthetics, then simple carbon filter or counter-top faucet unit may suffice. A word of caution is in order here: Be sure to change the filters at the appropriate intervals recommended by the manufacturer. If carbon filters are not changed at proper intervals, it is possible for phenomenon called "dumping" to occur. In simple terms, this is when a substantial portion of contaminants filtered out (trapped) is released due to exhausting the capacity of the filter, creating a "chemical cocktail".

On the other hand, if you are concerned with potential dangerous chemicals in your water supply such as chlorine, THM's, PCB's, organic chemicals, pesticides, lead, bacteria, and other contaminants, then additional measures are required. These measures include prolonged-contact carbon filtration, ultra filtration, reverse osmosis, ultraviolet, ozone, and treatment with chemicals such as chlorine. Just remember: THERE IS NO INDIVIDUAL PROCESS THAT CAN SOLVE ALL WATER PROBLEMS! Each situation has to be assessed on a case-by-case basis, taking into consideration what the desired quality of the water needs to be, and the chemical analysis of the water to be treated.M

Carbon filtration is a marvelous method for removing chlorine, chemicals, pesticides and numerous other contaminants, providing it is applied properly. For example, you would not want to put a carbon filter on water that is microbiologically unsafe. This would require chlorination (with adequate contact time) ahead of the carbon filter, or some other method such as ultraviolet or ozonation to inactivate the bacteria. Some areas have experienced problems with cryptosporidium and/or girardia cysts (which are often resistant to chlorine). These little "devils" attack the gastrointestinal tract of individuals whose immune system has been compromised, and can cause death. In the early 1990's, thousands of people become sick and dozens died in Milwaukee as a result of cryptosporidium outbreak. There are special ceramic and other types of cartridges with an "absolute" rating of 1 micron or less, designed to remove these critters.

Other areas have high levels of total dissolved solids (TDS). TDS is the measure of sodium, chlorides, sulfates, carbonates, bicarbonates, calcium, magnesium, etc., in the water supply. At levels above the 500 mg/1 or ppm, it is desirable to reduce the TDS level. This can be accomplished with only three methods: deionization, distillation, and the most popular method: reverse osmosis (commonly called "RO"). Deionization and distillation are not as cost effective as reverse osmosis - thus the popularity of RO. Reverse osmosis is a method by which pressure is applied to a membrane, forcing the pure water through the membrane, with the impurities being flushed down the drain. RO is generally applied with other technologies, including micron filtration, carbon filtration and ultraviolet, producing exceptionally high quality drinking water.

Finally, when purchasing a system, you should be mindful of maintenance intervals and costs. Most systems need maintenance and filter changes at 6-12 month intervals. I would be highly suspicious of anyone who infers that longer intervals are adequate. THIS IS YOUR DRINKING WATER WE ARE TALKING ABOUT! Take nothing for granted and do your homework. A good system might cost a few hundred dollars, but unless you are treating a whole house or a large custom home, the system should not be expensive. It might cost a few hundred bucks, but be cautious about paying much more than that - you probably won't get a better system! Here are quality reverse osmosis systems that aren't overpriced, and you can contact the following organizations for further information: U.S. Environmental Protection Agency's Safe Drinking Water Hotline at (800) 426.4791, or check them out on the web at, and Water Quality Association at (630) 505.0160,

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April 18, 2008 mark

The question you ask is very subjective. The US EPA Secondary Drinking Recommendations is that under 500 PPM is acceptable. A good RO system with proper pre-treatment should remove 90-98% of the TDS. On the other hand, the World Health Organization has taken the position that the calcium and magneisum minerals are important to cardiovascualr health. Therefore, they are against removing the minerals from the water. Myself? I prefer RO water and mine is about 20 PPM. Insofar as I know, a neutral pH (7.0 or thereabouts) is the best, but I am not a physician.

August 09, 2008 mark

Alain Moore wrote: we live in golden valley az, recently we were inform about having a presence of coliform bacteria in our ther any type of home water filtration system, that we can install for this problem Alain, I would recommend filtration in the range of 5 to 1 micron absolute followed by an ultraviolet light, properly sized, of course. That will solve your problem.

August 30, 2008 rushik patel

hi,sir i planning to start a business on manufacturing of packaged drinking water in india.the site which i have selected has raw water of 300TDS. On purification by RO process the final water will be around 10-12 TDS. sir i am intrested to know wether 10-12 TDS water will be good enough to sell in the market? or rather can i have your opinion on what are the best characteristics drinking water should have?

August 30, 2008 mark

Rushik, 10 – 12 ppm is fine, but you can easily go lower. A bottling plant with a raw TDS should probably use the following: 1. Softening 2. Carbon Filtration 3. Reverse Osmosis 4. Ultraviolet and/ozonation. What type of equipment are you using?

October 01, 2008 Jim

Hi Mark, What is the difference between a 100GPD TF RO membrane and a 50 GPD one? Is one more efficient than the other? I recently changed my RO membrane because I was getting TDS readings of about 28. My new membrane was worse (44). Is the new one defective? Thanks!

October 01, 2008 mark

Jim, There should be very little difference between the membranes, except that the 100 GPD should make more water. The quality should be very close. When a new membrane is installed, there is usally a little elevation of the TDS until the membrane and tank are completely flushed. Secondly, what is your incoming TDS? You should get at least 90-95% rejection, and finally, did you change your drain flow restrictor? If you make more water, you need to flush more to drain.

October 01, 2008 Jim

Hi Mark, Thanks so much for sharing your time and expertise!! My tap water TDS is 547. This is from a KDF whole house filter system with a 1 micron carbon block final output filter. I did not change the drain flow restrictor since I do not even know what it is :( But, all I did was to replace the TF-1812-50 with another TF-1812-50. (I did notice that the original had more windings of membrane than the replacement) Again, thanks for your assistance. —Jim

October 01, 2008 Jim

Mark, I am sorry that I forgot to tell you that I did completly empty the current tank, let it fill, and empty it again to get the 44 TDS reading on my new “HM digital” TDS-4 meter.

October 01, 2008 mark

The drain restrictor is on the outlet of the membrane, and if you changed from a 50 GPD membrane to a 100 GPD membrane you will need a bigger flow restrictor. DO NOT RUN THE RO LONG WITHOUT THE PRIPER FLOW RESTRICTOR AS IT WILL RUIN IT! You will need a flow restrictor like the one here: You will need the 850 ml restrictor. If you do not have a flow restrictor like this, then it is in the elbow coming out of the membrane. Unscrew that elbow and pull out the flow restrictor plug, re-tape with teflon and screw it back in. Then install the above drain restrictor on the drain line.

October 24, 2008 Jane

I live on the coast and recently installed a 550 foot well and had a lot of salt in my water. My plumber just got my water test results back and the testing company said I have TDS at 2970/ppm and sodium at 2850/ppm. Is there any way an undersink R/O will purify my water enough for drinking from the tap?

October 25, 2008 mark

Jane wrote: “I live on the coast and recently installed a 550 foot well and had a lot of salt in my water. My plumber just got my water test results back and the testing company said I have TDS at 2970/ppm and sodium at 2850/ppm. Is there any way an undersink R/O will purify my water enough for drinking from the tap?” Jane, An undersink RO will not typically work for this application. You will need a pressure-boosted system that will operate at 200 PSI. You will need some space for a system like this. At our website site, we have a system called the R13 that would be a good choice.

October 28, 2008 Jane

Thanks Mark. A couple of questions about the R13. 1. What is the homeowner maintenance requirements for this type of system? 2. Can the system be mounted on an external wall or does it have to be contained in a separate building? 3. Does it have a guarantee? 4. Can any plumber install it or should they be certified? This is the best option I have found so far. Thank you very much for your assistance.

October 28, 2008 mark

1. Change filters and membranes as needed based upon water usage; 2. It can be mounted anywhere (that it won’t get wet or freeze); 3. 1-year warranty; 4. Any plumber can install it – we just suggest that they talk with us on the phone before they do it and call us with any questions. The only “dumb” question is the one they don’t ask!

August 25, 2010 Pam Vasquez

Our Culligan reverse osmosis system stopped working (no water in the tank) while we were on vacation and so did out icemaker. I called our plumber to find out if there was a problem with water not entering each system. He found that water was indeed entering and after he left, the icemaker started working and continues to work. Before we call Culligan, we would like to know if you might have an idea as to what the problem is. We have not changed the filters for over a year? Thanks in advance.

August 29, 2010 mark

Pam, It could be any number of things, but I would change the filters first, since it has been over a year. Also check the incoming TDS and the TDS through your RO system. If it’s not rejecting 85%, you should replace the membrane. It also could be a bad tank or a bad Auto Shut-off Valve.

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