A Question For The Hydraulically Inclined And Chemically Clever
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I just instituted a formal water testing and tracking program at work and discovered something disturbing that I can't explain. We have a small development built in the past 6 years, comprised of about a half mile square of fairly new homes. All piping is done with new PVC pipe, EPA approved for potable water. We measure the pH at the inlet to the development, and sample it at 4 homes scattered through the neighborhood. At the inlet the pH is consistently 7.18, but when it is tested at the homes it measures 8.5!!! I wasn't the best chemistry student in college, but I passed and understood more than I let on to the teacher. This shouldn't happen in a chemically neutral pipe! That's an awful lot of hydrion getting in there in a very short run. The testers used the same meter at all locations, and the temperature didn't vary by more than a degree F. Today's quiz has one question: what could cause such a large shift in pH?
Will Rogers never met me.
how are the PVC pipes connected? welded? solvent welded? any chance the joins contaminate? you could have the 8.5 sample analyzed. PS: watch out for angry rodents, they are known for creating havoc anywhere. :)
Luc Pattyn [Forum Guidelines] [Why QA sucks] [My Articles] Nil Volentibus Arduum
Please use <PRE> tags for code snippets, they preserve indentation, and improve readability.
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The actions of dissolved gasses in the water could explain it.
Join the cool kids - Come fold with us[^]
My 5. See my two posts below.
Software rusts. Simon Stephenson, ca 1994.
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I just instituted a formal water testing and tracking program at work and discovered something disturbing that I can't explain. We have a small development built in the past 6 years, comprised of about a half mile square of fairly new homes. All piping is done with new PVC pipe, EPA approved for potable water. We measure the pH at the inlet to the development, and sample it at 4 homes scattered through the neighborhood. At the inlet the pH is consistently 7.18, but when it is tested at the homes it measures 8.5!!! I wasn't the best chemistry student in college, but I passed and understood more than I let on to the teacher. This shouldn't happen in a chemically neutral pipe! That's an awful lot of hydrion getting in there in a very short run. The testers used the same meter at all locations, and the temperature didn't vary by more than a degree F. Today's quiz has one question: what could cause such a large shift in pH?
Will Rogers never met me.
Reading the other replies (particularly Elaine's) and starting on the day's caffeine intake, I'd be guessing the dissociation of dissolved carbonates, releasing CO2 and leaving bases behind. Try leaving an "input" sample stand for a day or so and see what it registers. Cheers, Peter [might have to amend my sig - so does Roger's PVC ;P ;P ;P ]
Software rusts. Simon Stephenson, ca 1994.
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I just instituted a formal water testing and tracking program at work and discovered something disturbing that I can't explain. We have a small development built in the past 6 years, comprised of about a half mile square of fairly new homes. All piping is done with new PVC pipe, EPA approved for potable water. We measure the pH at the inlet to the development, and sample it at 4 homes scattered through the neighborhood. At the inlet the pH is consistently 7.18, but when it is tested at the homes it measures 8.5!!! I wasn't the best chemistry student in college, but I passed and understood more than I let on to the teacher. This shouldn't happen in a chemically neutral pipe! That's an awful lot of hydrion getting in there in a very short run. The testers used the same meter at all locations, and the temperature didn't vary by more than a degree F. Today's quiz has one question: what could cause such a large shift in pH?
Will Rogers never met me.
My guess 1 : Corrosion of water taps and PVC pipe joints. My guess 2 : PVC is cracked somewhere and there is a sewage water running above it !!! (Don't stop drinking water :laugh: ) My guess 3 : Your pH measure meter is being biased to the different places !!! ;P
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I just instituted a formal water testing and tracking program at work and discovered something disturbing that I can't explain. We have a small development built in the past 6 years, comprised of about a half mile square of fairly new homes. All piping is done with new PVC pipe, EPA approved for potable water. We measure the pH at the inlet to the development, and sample it at 4 homes scattered through the neighborhood. At the inlet the pH is consistently 7.18, but when it is tested at the homes it measures 8.5!!! I wasn't the best chemistry student in college, but I passed and understood more than I let on to the teacher. This shouldn't happen in a chemically neutral pipe! That's an awful lot of hydrion getting in there in a very short run. The testers used the same meter at all locations, and the temperature didn't vary by more than a degree F. Today's quiz has one question: what could cause such a large shift in pH?
Will Rogers never met me.
dude, try a binary search of the pH levels of the pipes so you know the start value, the end valie - what accessible junctions are in between and what are the pH levels at these places? If gets all lnear etc then i'd guess the pipes are a bad batch EPA approved or not (external leakage excluded) But you might find something else to do with the adhesive or something else interesting? Best start - do the binary search. Hell of an interesting problem to work on though :) Bryce
MCAD --- To paraphrase Fred Dagg - the views expressed in this post are bloody good ones. --
Publitor, making Pubmed easy. http://www.sohocode.com/publitorOur kids books :The Snot Goblin, and Book 2 - the Snotgoblin and Fluff
modified on Wednesday, September 29, 2010 7:17 PM
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I just instituted a formal water testing and tracking program at work and discovered something disturbing that I can't explain. We have a small development built in the past 6 years, comprised of about a half mile square of fairly new homes. All piping is done with new PVC pipe, EPA approved for potable water. We measure the pH at the inlet to the development, and sample it at 4 homes scattered through the neighborhood. At the inlet the pH is consistently 7.18, but when it is tested at the homes it measures 8.5!!! I wasn't the best chemistry student in college, but I passed and understood more than I let on to the teacher. This shouldn't happen in a chemically neutral pipe! That's an awful lot of hydrion getting in there in a very short run. The testers used the same meter at all locations, and the temperature didn't vary by more than a degree F. Today's quiz has one question: what could cause such a large shift in pH?
Will Rogers never met me.
Actually, that shift isn't too great, the pH Scale is logarithmic, but 8.5 is at the edge of what is considered drinkable. If you are really worried, aquarists shops (the ones that sell fish as pets) have a good range of chemical testing kits, not just for pH but other dissolved ions. My main suspicion would be on limescale build-up in the pipes, if you have trouble getting shaving foam to foam that could well be the problem. Could the problem be filters fitted in the houses?
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Actually, that shift isn't too great, the pH Scale is logarithmic, but 8.5 is at the edge of what is considered drinkable. If you are really worried, aquarists shops (the ones that sell fish as pets) have a good range of chemical testing kits, not just for pH but other dissolved ions. My main suspicion would be on limescale build-up in the pipes, if you have trouble getting shaving foam to foam that could well be the problem. Could the problem be filters fitted in the houses?
Keith Barrow wrote:
Could the problem be filters fitted in the houses?
wouldn't that require one-way valves to be absent or defective? every house is supposed to have one AFAIK. :)
Luc Pattyn [Forum Guidelines] [Why QA sucks] [My Articles] Nil Volentibus Arduum
Please use <PRE> tags for code snippets, they preserve indentation, and improve readability.
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I just instituted a formal water testing and tracking program at work and discovered something disturbing that I can't explain. We have a small development built in the past 6 years, comprised of about a half mile square of fairly new homes. All piping is done with new PVC pipe, EPA approved for potable water. We measure the pH at the inlet to the development, and sample it at 4 homes scattered through the neighborhood. At the inlet the pH is consistently 7.18, but when it is tested at the homes it measures 8.5!!! I wasn't the best chemistry student in college, but I passed and understood more than I let on to the teacher. This shouldn't happen in a chemically neutral pipe! That's an awful lot of hydrion getting in there in a very short run. The testers used the same meter at all locations, and the temperature didn't vary by more than a degree F. Today's quiz has one question: what could cause such a large shift in pH?
Will Rogers never met me.
Deodorant? :-D
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I just instituted a formal water testing and tracking program at work and discovered something disturbing that I can't explain. We have a small development built in the past 6 years, comprised of about a half mile square of fairly new homes. All piping is done with new PVC pipe, EPA approved for potable water. We measure the pH at the inlet to the development, and sample it at 4 homes scattered through the neighborhood. At the inlet the pH is consistently 7.18, but when it is tested at the homes it measures 8.5!!! I wasn't the best chemistry student in college, but I passed and understood more than I let on to the teacher. This shouldn't happen in a chemically neutral pipe! That's an awful lot of hydrion getting in there in a very short run. The testers used the same meter at all locations, and the temperature didn't vary by more than a degree F. Today's quiz has one question: what could cause such a large shift in pH?
Will Rogers never met me.
It's a long shot, but are you measuring the water from the faucet in the house? Perhaps the mineral buildup in the pipes in the house is causing it (the pipes in the house might be a different material than PVC)? Also, there are water purifiers sold today that also increase the pH of the water. Perhaps each house happens to have one of these? Maybe there is an intermediate processing center (not sure what that might be) that all the water passes through? Maybe the source of the water is not what you think it is (e.g., the water comes from multiple locations)?
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I just instituted a formal water testing and tracking program at work and discovered something disturbing that I can't explain. We have a small development built in the past 6 years, comprised of about a half mile square of fairly new homes. All piping is done with new PVC pipe, EPA approved for potable water. We measure the pH at the inlet to the development, and sample it at 4 homes scattered through the neighborhood. At the inlet the pH is consistently 7.18, but when it is tested at the homes it measures 8.5!!! I wasn't the best chemistry student in college, but I passed and understood more than I let on to the teacher. This shouldn't happen in a chemically neutral pipe! That's an awful lot of hydrion getting in there in a very short run. The testers used the same meter at all locations, and the temperature didn't vary by more than a degree F. Today's quiz has one question: what could cause such a large shift in pH?
Will Rogers never met me.
Oh. Thought I might have something to contribute under Chemically Clever, but then I realized you were talking about engineering... :doh:
Christopher Duncan
www.PracticalUSA.com
Author of The Career Programmer and Unite the Tribes
Copywriting Services -
Roger Wright wrote:
That's an awful lot of hydrion getting in there
Let's look at it in context. Assume that what you start with is close to 100% H2O. Adding 3 parts per million (by mole) of a fully dissociated[*1] monoacidic base will give you a pH of 8.5 (pOH of 14.0 - 8.5 = 5.5). You can get big changes in pH around the neutral range adding little amounts of "stuff" to non-buffered water. Changing pH 7 to 8 takes very little more than looking at it, but pH 12 to 13 is equivalent to moving a mountain or two. Having said all that, I have no idea what your contaminant is. My point is that it's not very plentiful. [*1]many inorganic and organic bases will be nearly fully dissocated at 3 ppm. Cheers, Peter ps If we want to take this any further, I might invoke my daughter's Chem PhD! ;P
Software rusts. Simon Stephenson, ca 1994.
:-O I forgot about that... it takes very little to drive the pH a couple of points; it's logarithmic, IIRC. Heck, it could just be oxidation occuring at the hose bib where the samples are taken, and a lot of these homes are plumbed with copper pipe. But it is the only place in our entire system where this is happening, and most of the other homes were built by the same contractors (similar materials assumed).
Will Rogers never met me.
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Just to eliminate the obvious, are you sure you didn't simply have a bad ph test? Otherwise, I imagine there are lots of things you could try to investigate it. Off hand I can't see how PVC would make water more alkaline. Did you let the water run at the house for a minute before sampling, or grab the first drops from the tap? Perhaps the fittings are electrolyzing or something. I'd try flushing out the water at each home for a minute, then sample there, then at the inlet. I'd also repeat the experiment a couple times to see if the PH changes over time. Maybe the water main itself is changing due leaks & exposure to minerals etc... -- Ian
I'm fairly sure that the tsts are being run correctly, as the same two guys do all the tests and they're both EPA certified operators. And you're right, there's nothing in PVC that can cause a pH shift; the cause must lie elsewhere.
Will Rogers never met me.
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Send a sample to a lab and get a BOD and COD workup as well as a break down of contaminants. Of, course, the homes themselves may not be using the same PVC, faucets could be dirty. Are you checking in the homes or at the cutoff valve outside the home at the water meter?
Need custom software developed? I do custom programming based primarily on MS tools with an emphasis on C# development and consulting. I also do Android Programming as I find it a refreshing break from the MS. "And they, since they Were not the one dead, turned to their affairs" -- Robert Frost
We're testing at the faucets on the exterior of the houses, since there are no taps installed on the mains. We do periodic testing for a wide range of contaminants, and none show unusual results. BOD and COD are among those tests, along with monthly tests for bacterial activity.
Will Rogers never met me.
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how are the PVC pipes connected? welded? solvent welded? any chance the joins contaminate? you could have the 8.5 sample analyzed. PS: watch out for angry rodents, they are known for creating havoc anywhere. :)
Luc Pattyn [Forum Guidelines] [Why QA sucks] [My Articles] Nil Volentibus Arduum
Please use <PRE> tags for code snippets, they preserve indentation, and improve readability.
It could be beavers chewing through the lines and pissing in them (see Christian's post), but the lack of dams in the desert nearby suggests that the cause may lie elsewhere.
Will Rogers never met me.
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Reading the other replies (particularly Elaine's) and starting on the day's caffeine intake, I'd be guessing the dissociation of dissolved carbonates, releasing CO2 and leaving bases behind. Try leaving an "input" sample stand for a day or so and see what it registers. Cheers, Peter [might have to amend my sig - so does Roger's PVC ;P ;P ;P ]
Software rusts. Simon Stephenson, ca 1994.
That's an interesting thought. I'll suggest a round of "day after" testing. Thanks! :-D
Will Rogers never met me.
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dude, try a binary search of the pH levels of the pipes so you know the start value, the end valie - what accessible junctions are in between and what are the pH levels at these places? If gets all lnear etc then i'd guess the pipes are a bad batch EPA approved or not (external leakage excluded) But you might find something else to do with the adhesive or something else interesting? Best start - do the binary search. Hell of an interesting problem to work on though :) Bryce
MCAD --- To paraphrase Fred Dagg - the views expressed in this post are bloody good ones. --
Publitor, making Pubmed easy. http://www.sohocode.com/publitorOur kids books :The Snot Goblin, and Book 2 - the Snotgoblin and Fluff
modified on Wednesday, September 29, 2010 7:17 PM
No one has ever looked at the data before - they've collected it, then tossed the information in the circular file if there was nothing bad apparent. What I'm doing is collating the data and looking for patterns and trends for the first time. I suspect this is the first of many curious things I'm going to discover...
Will Rogers never met me.
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Actually, that shift isn't too great, the pH Scale is logarithmic, but 8.5 is at the edge of what is considered drinkable. If you are really worried, aquarists shops (the ones that sell fish as pets) have a good range of chemical testing kits, not just for pH but other dissolved ions. My main suspicion would be on limescale build-up in the pipes, if you have trouble getting shaving foam to foam that could well be the problem. Could the problem be filters fitted in the houses?
Scale buildup is a problem, but it's not lime - iron and manganese are our main problems in this area. The groundwater is saturated with the stuff. Our testing is quite a bit more sensitive than anything a fish store can offer - lab testing is one of our largest expenses, but well worth the cost for safety reasons. We don't scrimp there, ever! Samples are taken on raw water, btw, before entering any filter system.
Will Rogers never met me.
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Deodorant? :-D
The water in this development is far better than what we have at the office - we aren't served by our own system, being in another company's territory. ;P The water at the office isn't fit to wash toilets in; after running the tap for a few minutes, one of us has to fart, just to clear the air.
Will Rogers never met me.
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It's a long shot, but are you measuring the water from the faucet in the house? Perhaps the mineral buildup in the pipes in the house is causing it (the pipes in the house might be a different material than PVC)? Also, there are water purifiers sold today that also increase the pH of the water. Perhaps each house happens to have one of these? Maybe there is an intermediate processing center (not sure what that might be) that all the water passes through? Maybe the source of the water is not what you think it is (e.g., the water comes from multiple locations)?
Good ideas, but none apply. We know the exact source, have good maps of the installation, and the water is taken from outside taps which no one would apply a filter or treatment system to because of the cost. Inside plumbing might be different - copper, perhaps - but I can't prove it, and it seems unlikely that water taken from 4 randomly chosen homes would show the same pattern. It most likely is something systemic, but it's hard to pin down so far...
Will Rogers never met me.
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Oh. Thought I might have something to contribute under Chemically Clever, but then I realized you were talking about engineering... :doh:
Christopher Duncan
www.PracticalUSA.com
Author of The Career Programmer and Unite the Tribes
Copywriting Services:laugh: I'm always open to suggestions, if you have some good recipes. :-D
Will Rogers never met me.