Wednesday, December 23, 2009

Eliminating Ferric Iron from Well Water

After digging our well, we had the water tested for over a hundred different possible problems; the good news is that it had only two deficiencies.  The beautiful stones in this county have iron deposits all over them, so we weren't surprised to learn that our ground water had iron in it too.  (about 4 grains per gallon)  The other problem with our water was that it had a low ph.  (roughly 6.2)  For a while, we lived with the iron in the water, but it was staining our fixtures, so we decided to fix it before the stains became permanent.

There are two major forms of iron that can be present in water supplies... "ferrous" (dissolved and temporarily invisible) and "ferric" (oxidized and visible).  Our water test showed that ours was primarily the ferric form of iron... which is common in dug wells where the water has had ample time to come in contact with oxygen.  It's also the easiest form to remove.  After researching on the internet (and experimenting with disposable filters, which temporarily worked before clogging with iron), I decided to use a filter tank (shown at left) with back-washable filter media in it.  I was relieved that I wouldn't need a water softener that requires adding salt all of the time.

Because city water has recently been made available to many areas of our county, spun-fiberglass filter tanks are sitting unused in basements and cellars.  My in-laws gave me one of theirs.  The first thing I did was to dispose of the clunky and complicated backwashing valve-set on the top of the tank.  (more on that later)  After reinstalling the down-tube in the middle of the tank, I poured in crushed garnet, Birm, and Chemsorb.  The garnet doesn't really filter anything - it's just a heavy bed for the other media to rest on.  The Chemsorb filters out the ferric iron as does the Birm.  But the Birm will also convert a small amount of ferrous iron to ferric iron if it is present in the water and if the ph is in the proper range.  Either media alone might have worked for my application, but I couldn't decide, so I used both!

I installed a manual ball valve on the filter tank, so that when I opened the ball valve, pressurized water in the blue expansion tank pushed water backwards through the filter tank, thereby floating the media in the filter tank, and flushing the iron out a garden hose. I also installed a second check valve on the line coming from the well - to make sure my setup didn't push rusty water back into to the well.

I worked the ball valve manually every day for a few weeks, watching the color of the back-washed water to see how long the backwash cycle needed to be in order to get all of the iron out, without wasting too much water.  (the answer, 2 minutes at about 5 to 8 gpm)  About two weeks into my test run, the system stopped working, and tons of iron started coming out our faucets. Blechk.  But we were also getting some air in the lines occasionally, so I had a theory... It turns out, the rubber bladder in the blue expansion tank had burst.  The blue expansion tank still worked, but the ruptured bladder let water come in contact with the inside of the metal tank, forming rust downstream of my filter system.  I called the expansion tank manufacturer and had them send me a new bladder.  Once I installed it, my system started working fine again.

The final step was to automate the back washing function.  For less than $40, I bought a battery operated sprinkler valve from Lowes, and set it to open up for 2 minutes every night at 3:00 am.  The system has been working great for over two months now. The media is supposed to last for at least 5 years, and I hope it does!  This picture shows (from left to right) the sprinkler valve, the manual ball valve (always open now), and the brass check valve on the line coming from the well.

Three final notes: 
#1.  My setup, which places the filter tank before the expansion tank, may not work in situations where the well pump flows more than 3 gpm.  (My pump only flows 1 gpm, and my expansion tank can store at least 30 gallons of water) 

#2  My well pump is configured to spray water back into the well, so that oxygen levels are always high in the well water.  I think this helps make sure all of the "ferrous" iron becomes "ferric" iron before it gets to the filter tank.  I also think this helps kill bacteria in the well, without using chlorine or other methods.

#3.  I haven't fixed the ph problem yet.  The water is safe, but the low ph will possibly cause corrosion in my copper pipes.  In fact, my water leaves a green ring in the bath tub... probably from my copper pipes.  I have 50 pounds of calcite that I plan to pour in the well to see if that will work.  (I've read that it will!)  Acidic water should not be a problem in areas where limestone is naturally occurring in the ground.  Such is not the case on our farm. 

Here's a final picture of the crystal clear water we get from our well when we draw a bath now...


Blogger karl said...

An ingenious workaround and great explanation of your water chemistry at the same time... I'm surprised to hear that you didn't use pex for plumbing runs. was there a reason for that? Or are you using the copper terminations to the pex runs?
It also helped jog my memory to trouble shoot a problem with water at my barn which has a bladder tank. Probably mine has also recently ruptured as I no longer build pressure in it...

December 23, 2009 at 6:57 PM  
Blogger Thomas Massie said...

thanks Karl. some of the old expansion tanks had no bladder in them. they get waterlogged and need to be recharged with compressed air - the symptom is the well pump keeps cycling on and off. I couldn't believe the bladder ruptured in my new tank. To make the final diagnosis, I unhooked the tank from the water lines and refilled it with compressed air (it has a little valve stem for doing that), and then witnessed air coming out the bottom of the tank where only water should have been coming out. It was weird though - sometimes, the ruptured bladder would lay against the inside of the tank in such a way as to seal itself back up and hold pressure. uggh.

I used pex for the radiant heat, and for the runs to my toilets and washing machines. But I used copper for any lines that carried water for human contact. I think water gets stale and nasty when it sits for long times in plastic lines. Of course, the 800 foot line from my well to my house is all plastic though, so who knows. The old dudes around here with stainless "stills" insist on a copper worm. ha ha.

December 23, 2009 at 9:26 PM  
Blogger MarcusCalidus said...

Hi Thomas,
I know about those guys preferring copper runs (my father in law is an old school plumber)
But in your case even he would have used PEX runs I guess.

With us here in Germany using copper has to be verified (according to the Drinking Water Ordinance 2003) if you use new runs and pH below 7.4.

As you already see green color in your tub using your water for drinking purposes is critical for smaller children since they don't have the ability to get rid of the copper but store it in their liver. I would recommend sending your water to some lab to check for it's ingredients. In Germany the maximum allowed value is 3 milligrams per litre but it is said that little children can risk their health at copper concentration above 0.8 milligrams per litre.

Even if you get rid of the acid in your well then your water still may be to soft for using copper (in Germany again the water must not be below 7 degree dH - deutsche Härte (sorry I don't know the US measurment for water hardness))

That was one of the reasons I changed my runs to PEX last year.

I wish you all the best with your work :-) ...

Kind regards


January 4, 2010 at 7:42 AM  
Blogger Thomas Massie said...


Thank you for instilling a new sense of urgency for me to fix the Ph problem! All of our drinking water goes through a Reverse Osmosis unit that I plumbed to the refrigerator... which removes copper... but I just googled "reverse osmosis copper" and found something else I did not know... copper runs should not be used after R.O. units, as the water is even more corrosive after the R.O. (even though it is more pure). Whoops. I have about 7 feet of copper between the R.O. unit and where it goes into our fridge. Darn the copper!

January 4, 2010 at 8:09 AM  
Blogger Thomas Massie said...

Ironically, I typed that while drinking my coffee made with low ph, presumably copper-ful water. Often we get water for coffee straight from the faucet since the R.O. unit in the fridge has such a low flow rate (slow) and is chilled. (Fortunately, our kids don't drink the coffee we make with the non- R.O. water.) My new year's resolution is now to: "quit drinking copper!"

I will definitely do a post to let everyone know how the pH fix goes. There are multiple sol'ns available - but I'm hoping the calcite chips work first. I'm dumping them in today!!!

thank you again Marco!


January 4, 2010 at 8:23 AM  
Blogger Thomas Massie said...

OK, I didn't get the chips in today, but I ordered a copper test kit on line!

January 4, 2010 at 9:28 PM  
Blogger Thomas Massie said...

Test results:

Hot water tap: 1.2 ppm
Cold water tap: 0.8 ppm
Reverse Osmosis: 0.0 ppm

From a health standpoint, it looks like we're in pretty good shape. To be sure, we'll make sure the kids drink water from the fridge tap that is plumbed to the R.O. unit. I'll do another test after I add the calcite ships to the well (still haven't done... too cold !). Raising the ph will not only lower the copper at the tap - it should also prolong the life of my plumbing and fixtures.

Thanks Marcus for the suggestion to be wary of copper concentrations.

January 13, 2010 at 4:29 PM  
Blogger brad_bb said...

Hey, updates are supposed to go in the blog, not the comments!! :P

February 12, 2010 at 7:39 PM  
Blogger brad_bb said...

Oh, and what kind of life is that hose timber valve rated for. The ones I used for my timed drip watering system occasionally have issues, so I wonder about the longevity of yours, or how you'll know if you have a problem. I guess you should be able to tell in the water though, the feel or color.

February 12, 2010 at 7:42 PM  
Blogger Thomas Massie said...

I can exercise the valve every now and then when in the basement. So far it seems to be working fine. The calcite dumped into the well did NOT measurably change the PH. Hmmm.

February 20, 2010 at 1:29 PM  
Blogger brad_bb said...

No updates for awhile - too busy campaigning?? Understandable. Just got back from a local tea party event myself. You think you've got problems, at least you don't have the political nightmare we do in IL! I'm well overdue for a blog update as well. I've done stuff, just haven't updated. Hope all is well, Brad

February 26, 2010 at 9:25 PM  
Blogger Bigshow said...

Ok Massie...this is ridiculous.

April 14, 2010 at 9:45 PM  
Blogger Thomas Massie said...

so true bigshow. I'm running for election and the primary is on May 18th. After that, there _will_ be updates! :)


April 15, 2010 at 10:13 PM  
Blogger littlehillbaby said...

updates updates updates :) I luv reading your blog and hope all goes well in your upcoming election! Living off the grid sounds awesome. I live in Alabama now but all my family are still in Vanceburg and will be voting Massie all the way!

May 5, 2010 at 7:11 PM  
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June 10, 2010 at 5:41 AM  
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September 13, 2010 at 6:21 AM  
Anonymous Anonymous said...

What were the quantities of each of the three, garnet, brim and chemsorb used in the filter?

August 18, 2011 at 4:58 PM  
Blogger Thomas Massie said...

Anon, if I remember correctly, I used about equal amounts of brim and Chemsorb. The garnet is denser, so although I might have used an equal amount of it by weight, it was smaller by volume. Its purpose is simply to support the other media. When backwashing occurs, the garnet should remain undisturbed, but the other media floats and churns so as to clean it.

The system has been working great for almost two years now. It removes all of the iron, and it is only necessary to backwash for 2 minutes every 3 days. The amount of each media to use will depend on the volume of your tank. Do not fill it to the top though, there needs to be room for the media to float when backwashing.

The only problem I have with my water is that it is that the ph is so low that it picks up copper from the pipes. The reverse osmosis removes the copper from the water we drink so it is not a health hazard.

September 4, 2011 at 5:21 PM  

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