blackened water

dianekyFebruary 19, 2007

We have a water softener in which we use potassium salt. We are on city water, not a well. We have been getting a "shot" of blackened water appearing anywhere from 5 to 20 seconds after starting to run our bath and it only lasts about 5 seconds before becoming clear water again. We don't seem to see get it at any other taps but then maybe its just more visible against the light colored bathtub. It seems to be worse in the 1 - 2 days after the softener has regenerated and the water is at its softest. It is also more concentrated in the hot water than the cold. Our plumbing is a combination of copper pipe and flexible hose-pipe. Our house is 50 years old so some of the copper pipe is that old. Any of the flexible pipe is less than 2 years old as is our hot water tank. Is the softener salt leaching something out of our water lines or faucets? Could the water be reacting with the aluminum sacrificial rod in the tank? This problem did not start immediately after installing the softener. It has just recently developed about one and a half years after installing the softener, tank, flexible pipe.

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There are a number of causes for the symptoms that you describe.

I would have your water tested both before and after the softener, both cold nd hot water for hardness.

Normally city water is easier to handle than most well waters becuase it is 'pretreated' and rarely varies on a day to day basis.

However, occasionally a water main may breach and horribly dirty water ('boil alerts' etc.) enters the home. With those having a softener, some of that is filtered out by the softener before entering the home and remains in the softener. Often this dirt is too heavy to backwash effectively and remains in the softener and reappears shortly after regeneration for a short time period.

Also, if the chlorine levels from the city exceed 0.5ppm, which is most likely, the resins will suffer--become spongy--and begin the fail in their job. They must be replaced or the softener remains ineffective.

From description, it is difficult to determine that the 'soot' may be coming from the water heater only. I would wager that if you drained the WH you would notice a the sludge. Be careful when draining that as not to damage it.

Salt should not be coming through your lines if the softener is working properly. I don't know of any studies that should potassium leaches pipes or fixtures. If anything, it leaves a scale build-up.

Another cause may be that your softener is not working all the time and actually leaves deposits on your pipes as it is nearing its regeneration. After the water softener goes through its cycle and starts producing soft water again.
It may start to release this temporary scale build up.

Anyway, further testing and examination is needed.

Andy CWS

    Bookmark   February 20, 2007 at 9:09AM
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Did you use a clear glass and fill it from the other fixtures to make sure you are not getting it there also?

So lets assume you did and it is present at any of the other fixtures. If it little black spots floating around in the water then it could be a dissolving black rubber gasket in the fixture or a valve that feeds the fixture. If it is in the whole house then as the last poster said it's probably in the softener

    Bookmark   February 20, 2007 at 11:48AM
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Andy and rjoh, thank you for your responses.

rjoh: We have never seen a shot of blackish water come out of any other tap other than the one bathroom (the one most recently renovated with the pex hose attached to older copper pipe). When I have captured this water in a glass, I cannot see any actual black particles despite the dark grey appearance of the water.

Andy: our water always has that slippery feel of softened water so I don't think it is failing to regenerate properly. But if it was, what is the composition of the temporary deposits you are referring to? Any deposits I have around my sink taps is of a soft, whitish, toothpasty consistency. The city was doing work on some water lines (cast iron) in an adjoining neighborhood the year we did our renovations and installed the softener. We had about a week of intermittent yellowish water coming in through the whole house that the city said was due to disturbed rust from the old cast iron pipes they were working on in the other neighborhood. Could there be a connection if there is remaining rust in the resin bed, i.e. does rust deposit turn black with time? Thanks for any more thoughts you may have on this. My husband has put draining the hot water tank on the to-do list. The biggest mystery in all of this is why just the one section of our plumbing getting this (wouldn't a softener or tank problem affect all the water lines?)and why just such a short burst of this discolored water.

    Bookmark   February 20, 2007 at 3:07PM
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Since it comes out of the one tap and one tap only, it has to be something in the lines to this tap. Is this a tub faucet? check everything downstream and the tub valve for some deposits that would make your water change color. It seems you will only have to go back to where the hot and cold tee off to the tub. See if you get it only on cold or hot. If you get it on both then its probably the tub valve.

    Bookmark   February 20, 2007 at 8:38PM
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rjoh: That was my first impression, that it had to be somewhere in the line to that bathroom. What's confusing me is that the tainted water can occur anywhere from 5 seconds to 30 seconds after the tap is opened, suggesting it's not right in the tub valve. We have a Grohe faucet with a thermostatic mixer. I only see it coming out of the tub filler, have not seen it come from the shower head, but maybe with the shower water coming out as a spray it wouldn't be as visible. Because of the thermostatic mixer I always run the tub with mixed water. About a week ago, I decided to just run hot and the tainted water was much darker than before which led me to believe that it is in the hot water and the cold was just diluting out the effect. Then yesterday I started the tub on hot water, got the usual shot of black water, turned the thermostatic knob to mixed water and lo and behold and second shot of tainted water came out a few seconds later, leading me to believe it also lurks somewhere in the cold line too. Confused yet? I sure am!

    Bookmark   February 21, 2007 at 11:59AM
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I don't know what to tell you, but my first impression that it probably lurks in the hot water line. water makes a good solvent and hot water would dissolve whatever deposit that is coming out faster. If you can get to the water lines feeding the tub, you could replace them if they are easy to get to. Since you don't drink out of the tub faucet I would learn to live with it. It might eventually clear itself up. It's probably coming out of some of the 50 yr old pipe and the softened water is knocking it off the wall of the pipe. While typing this I remembered something my FIL told me years ago. He is a retired water superintendent for a county here in Ohio. He told me they keep the hardness in the municipal water supply at a certain level to coat the insides of the pipes to keep lead from leeching out of the pipe joints into the water. The hardness builds a coating on the inside of the pipes in the houses with older plumbing. Since you are now softening the water the coating is probably dissolving into the water coming out of the taps. That could be making the discoloration.

A little story,

I was on well water at the old house and we had sulphur water. I replumbed the house with cvpvc before I put in a areator to get rid of the sulphur. The water also had iron bacteria in it and every once in a great while the sink in the bath would shoot out a little black stuff in the water. I figured it was the result of the water sitting in the tap for hours and somme residue on the inside of the pipe would let loose and come out in the sink. I got to the point of ignoring it. It wasn't worth the hassle of trying to figure out what was causing it or replacing the pipe etc....

    Bookmark   February 21, 2007 at 3:24PM
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Found an article about lead leaching from softened water.

Water Quality Factors Affecting Lead Content

Corrosion of the piping system, including the fixture and pumps, is a major factor in lead leaching into the water supply and the water quality itself impacts on corrosion. Several factors cause water to be corrosible including acidity, high temperature, low total dissolved mineral contents, and high amounts of dissolved oxygen. Hot water has much higher lead levels than cold and should not be used for cooking. Boiling water does not remove lead, but will increase concentrations.

Naturally soft water is known to be highly corrosive, but the Water Quality Association argues that soft water from water softeners does NOT increase the corrosiveness of water. They argue that naturally soft water has a combination of the previously stated quality factors including acidity which cause the corrosion, and it is not the softness which cause corrosion. In fact, they argue, if lead is found in water before it reaches the house, a water softener can significantly reduce lead levels.

Scientific data shows that the newer the home the greater the risk of contamination. It was found that lead levels decrease because mineral deposits form a coating on the inside surface of pipes as time passes.

Because of these positive and negative factors affecting lead levels, many communities use additives to water systems to control lead levels. New York is conducting studies to find the most effective concentrations of calcium orthophosphate for coating pipes to reduce lead leaching. Chicago uses additives to eliminate the acidity and increase the ability to coat pipes. Homeowners should contact their community supplier to discuss what control measures are being taken. Suppliers should, by law, be proactive in providing lead level control measures.

Variations with Draw Time

The amount of lead in a sample will vary substantially from first draw at a faucet to that found after flushing the lines. In one test in a first floor bathroom the first draw had lead levels of 900 parts per billion while after one minute of running the lead levels were reduced to 64 parts per billion. Lead will accumulate in the pipes as the water sits. The longer it sits, the larger the accumulation. Flushing the lines eliminates this accumulation.

For this reason, it is important to take at least two test samples (1st draw and 1 minute flush) for analysis for a better picture of conditions. If the first draw sample is higher than 15 ppb in lead levels, you should contact your supplier about the problem, and consider taking some corrective action, including installing a treatment system to remove the lead.

Treatment Systems

There are several effective treatment systems that consumers can install to significantly reduce lead levels at the faucet. Reverse osmosis, distillation, water softeners, and solid block and precoat adsorption filters, which are made with carbon to activiate alumina, are all effective in reducing lead levels in addition to removing other contaminants. Commonly used carbon filters for the purpose of removing chlorine and other chemicals are not effective in reducing lead. Contact the National Sanitation Foundation at (313) 769-8010 or the Water Quality Association at (630) 505-5161 on the effectiveness of filters in removing lead.


The EPA states that lead levels in your drinking water are likely to be highest if :

A. Your home has faucets or fittings made of brass which contain some lead or,

B. Your home or water system has lead pipes or,

C. Your home has copper pipes with lead solder and

-your home was built before 1988 or,

-you have naturally soft water or,

-water often sits in the pipes for several hours.

The best way for a consumer to find out if there is a lead problem in the house is to test the water at a qualified lab. For real estate sales inspections, Abbey Home Inspectors advises clients to take their own samples for testing to keep inspection costs to a minimum. The lead issue, whether in paint or water, can be the most important confronting a prospective homeowner. We feel that it is important to become knowledgeable on this meaningful subject.

Still I think the softened water could be removing some of the stuff coating the pipe going to the bath faucet or removing some residue in the bath faucet.

Still probably isn't anything that is going to hurt you since you don't drink from the tub spout.

    Bookmark   February 21, 2007 at 3:46PM
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rjoh: thank you so much for your thoughts and research. I too am inclined to just learn to live with it, i.e. run the tub filler to clear out the tainted water before putting the stopper down as I have been doing. Since we have a reverse osmosis system for our drinking water I'm going to try to not lose sleep over the thought of possible lead in my water. I'm also going to try to capture a black water shot and send it in to a local lab where my husband works just because my curiosity has been piqued. I'll keep you posted if I come up with anything.
Thanks again.

    Bookmark   February 22, 2007 at 12:34AM
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Seems the obvious might be overlooked here.

The color problem occurs in only one faucet, whether hot or cold water is running through it, and lasts for several seconds. To me, that is rather obviously a problem in the pipes leading up to the faucet. It just so happens in this case that those pipes are the only new ones in the house (correct?).

Since they are PEX pipes, it seems likely to me that the problem is occurring where the PEX meets the copper, which also makes sense given that the color lasts for 5-30 seconds -- that seems in the ballpark for the time it would take to flush that section of pipe. Either the transition fitting is corroding, or something was left inside the pipes that is causing this ongoing problem. Solvent perhaps? The only other possible explanation is the faucet itself (or perhaps the mixing valve), perhaps a corrosion problem or a metal-to-metal wear problem that creates a buildup inside the faucet or mixing valve that is flushed out each use. The duration of the color problem would then seem to be related to the amount of time since the faucet was flushed out. Does the color last longer when the faucet hasn't been used for a while?

I would take samples from several of your faucets, as well as multiple samples from the one problem faucet, and compare the results. If the problem is indeed isolated to only one faucet, I would replace it and any other component in common to both hot and cold lines, such as the mixing valve. If the problem then still persists, you know it is in the piping leading to that faucet, and can make an informed decision about whether it is worth replacing those pipes.

    Bookmark   February 22, 2007 at 2:25AM
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Matt: thank you for your reply. Just wanted to clarify that the length of time the black water lasts is always less than 5 seconds (hence that is why I have been referring to it as a "shot" of water). What does vary from 5 - 30 seconds is the length of time after I open the tap for the "shot" to appear. It is generally within 5 - 15 seconds, but there have been times when nothing has appeared that soon and I'm about to put the stopper down thinking there is no discolored water that day, when it will suddenly appear, i.e. sometimes as long as 30 seconds after normal water has been coming out. That's why we are stumped trying to localize it. 30 seconds after the tap has been running would make me think it is coming from beyond the pex-copper connection, whereas 5 seconds would make me think it is in the mixer itself. Sooooo confusing. We were in this house for 6 years with no problem, installed the water softener and new tank, then had this start happening about 2 years after the softener/tank/bathroom renovation. That's what has led me to think that the softened water is starting to affect something but what? and where? I haven't been able to find out if the lining of pex tubing is unstable in the presence of potassium ions. And I'm thinking about the pex because the only place we have pex in the house is the loop to and from the softener, and the line going to the renovated bathroom where this occurs. All the rest is copper. By the way, this shot of water has no abnormal odour associated with it. If I could feel comfortable that nothing is corroding to the point of failing, I'd just run my tub with the stopper up until the black water passes and ignore the whole issue. But if something is failing it would be nice to figure it out before I have a basement full of water. And besides, the scientist in me is deeply intrigued.
Thanks again for your thoughts - any more to add?

    Bookmark   February 22, 2007 at 2:45PM
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Hmmmm, that is a head-scratcher for sure. PEX is supposed to be inert, but who know what contaminants were in it when installed. Definitely have the black water analyzed, and catch it as black as you can. Once you know what it is, that should narrow down the problems considerably.

The only other thing that occurs to me is that something that was once covered in scale is now uncovering, due to the now softer water, and it releases sediment that settles out in low points and angles in the system, waiting to be flushed out the next time you use the faucet. Is this pipe the lowest in the house, or are there one or more 90-degree turns in it where sediment could hang out? You might want to take a wrench or hammer and bang on the pipes a bit, if you can get at them, and then run the water to see if the color is darker or lasts longer.

There's a show now on HGTV that specializes in solving mysteries like this. Can't remember the name of it, but your situation sounds perfect for them.

good luck!

    Bookmark   February 22, 2007 at 7:09PM
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I've just started having the same problem at the cottage on my ranch. It's a second house and was vacant for about 5 months. I AM on well water which is high in sulphur and iron. We don't drink it or cook with it but it's needed for all the other stuff but dish and clothes washers, showers etc.
Our experience has also been that it's a 'shot' event. Occurs only once in a while.
We're in the process of installing two 3,000 water tanks and have installed some copper piping. Could the metal in the water be reacting to the copper? One of the other things that happens is that out of all the faucets we get slightly yellow water but as soon as it's in a container, there is a rust colored precipitate that coats the bottom and sides of the container. Have always thought that this was the reaction of the water reaching air/oxygen as a well is a pretty closed system.
Any thoughts on the 'black shots' and well water? Have lived here for 24 years and not had this ever happen before and it's only in the cottage, not the main house.
Thanks for your help. I LOVE the internet!

    Bookmark   July 26, 2007 at 1:47PM
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Having a problem with black water coming from the hot water. The tank is clean and shows no sign of the black water,,,,something after the hot water tank. any ideas?

    Bookmark   July 19, 2008 at 7:03PM
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