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I am on a well in a rural area. Tests indicate that there is considerable iron in my water as well as air-borne bacteria. My bathroom fixtures turn rusty in about a week. Will an under-the-sink Watts reverse osmosis unit work for me or do I require an iron knockout unit between the well and the RO unit? I am concerned that the membrane will require replacement every few weeks due to excessive iron.
It would help to know more about your water test results. What do you mean 'air-borne' bacteria and how was this determined? What do you consider 'considerable"?
If you have iron, chances are you have hard water to a point that the calcium will also contribute to membrane failure. I wouldn't recommend an RO on more than 0.05 ppm iron. More will shorten the life of the membrane in relation to the total amount and volume of water used. There are ROs that have automatic membrane flush systems and these great increase the life of the membrane.
In the majority of cases, a softener will handle both calcium and iron (ferrous iron) which will give the RO excellent results. There may be other types of iron and this needs to be clarified before any water treatment equiment installed.
Andy Christensen, CWS-II
Hello Andy CWS
Thank you for your interest in my water problem. Sorry in the delay getting back to you but I finally found the results of my well test. The last test of my well found substances at concentrations above the guidelines. Iron (total) has a value of 2.53 mg/L compared to a guide of 0.3 mg/L. Sodium is at 357 mg/L compared to the guideline of 200 mg/L Total Dissolved Solids are 955 mg/L which are much higher then the suggested maximum of 500 mg/L. Calcium was measured at 1.3 mg/L. The report also stated that "Iron bacteria and sulphate bacteria were detected in water from the well. These are nuisance bacteria that are naturally present in groundwater. These and other bacteria can form a biofilm where mineral scale and other deposits buildup. Such deposits can reduce water quality, well yield, and well life expectancy. Shock chlorination is currently the method most often recommended to control nuisance bacteria."
We currently purchase all our drinking and cooking water. I would like to install a reverse osmosis system and use our own water if it will be safe and if it will operate efficiently with my well conditions. I do not have room to install an iron filter, nor a water softener. Will a back wash membrane flush system suit my particular conditions? Thanks, Rusty
With your water test results, I would not advise an RO as a stand-alone water treatment. High iron and ohter contaminants will be overbearing to the membrane and filters. There are larger ROs that are designed for problem waters but require more space than a softener.
When you say you don't have space for a softener, can you describe that issue a little more? Are you considering the size of 'normal' water softeners when evaluating size? I have rarely been stumped by the 'size' issue even though some concessions might have to be made.
Andy Christensen, CWS-II
And you also need to kill the IRB before using any RO.
If you don't have the space for the treatment equipment you need, you add the space or live with the water quality you have.
Many thanks Andy and Gary for the information. I was hoping that an RO unit would work here, but I am not surprised with your comments. I live in a cold climate and have no basement. My home is very small and there is no room for additional equipment. I had an under the kitchen sink RO unit when I lived in Arizona. I changed the filters as required and had sufficient potable water for home use. Now, living in the north, water conditions are just not good enough for an RO unit. Looks like I will just continue buying and lugging 5 gallon bottles back and forth. Rusty