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Question DetailsAsked on 10/22/2016

Can your water be too rusty because the well hit bed rock

We had a new well drilled last spring. They went down 62 feet and our water, which used to be clear, is now rusty. Clear water in both houses next door to us. Is it possible that they hit bed rock and that the water would be clearer if they had not gone so deep

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Sorry - AL cut off most of the answer first time around - then it cuts out all the paragraph breaks on me - ignore the "iiiii" strings - they are just to act as paragraph breaks -

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Sure - and in that case there a lot of possible solutions, depending on the well design and ground conditions:

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1) if casing was not concreted in, possibly pull it back (if it is in material where the skin friction is not too much for the drill to pull and it did not need a gravel pack around the screen), then tremie (underwater) pressure grout and concrete in the bottom of the well and reset a new screen (if existing is not long enough to work above the concrete) higher up in the "Good water" zone

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2) cut the casing above the bottom screen, pull it back, concrete in the bottom of the well (to say 10 feet or so above the bad water zone, assuming that still puts the new bottom well below water table) and put in an insert screen at the new depth

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3) if upper ground conditions are such a screen is not needed, tremie concrete in the bottom of the well and perforate the casing further up to let the "cleaner" water in

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4) if casing needs to be but cannot be pulled back economically (say it is concreted in) perforate casing and set new screen above tremied in well bottom - assuming screen does not have to be gravel packed

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5) if all else fails, drill new well nearby and abandon this one - grout/concreting it in (as appropriate to its design) to prevent the "bad" water from contaminating the "good" zone.

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Other possibilities -

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6) it may not be iron or manganese rich bedrock or sedimentary strata causing the problem. It may be you have corrosive water and they used a plain steel rather than stainless or PVC screen, and the screen is rusting.

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7) Or perhaps it should have been corrosion-resistant coated casing to prevent rusting in corrosive water.

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8) Or it could be they used drilling water that contained iron or manganse algae that contiminated your well, and you now have an iron algae bloom in the well - which could be treated and killed (sometimes permanently, sometimes only temporary fix) with a chemical treatment (usually hypochlorate, which disninfects it)

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9) if they used steel riser pipe on submersible pump or down to the foot valsve (above-ground pump), could be that is rusting

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10) if it is rusty initially but clears after some water use, could be they put in a cheap pump (assuming a submersible pump here) which is not all stainless, so it is rusting. However, this sort of clearing up (though more gradual) also occurs if metal in the well is rusting or you have algal growth, because as the water in the well is pumped out and replaced with "clean" groundwater the staining in the water will diminish too. However - if it stays pretty much the same rusty color after a lot of water use, say over about 5 volumes of the well (5 times the volume of the wetted depth of the well - water level to bottom of well), then a dirty water source would be expected to be the cause, because after extended pumping the "rusty" water in the well would be diluted by the incoming "clean" water.

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11) if there is grit/sand coming up from the well (tested at pump discharge, before it goes through any pressure or sand filtration tank or water softener) then it could also be that you are collapsing the surrounding soil - pumping in material from around the well due to insufficient or improperly sized well screen or screen filter packing, or a broken joint in the casing or damaged screen.

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12) if discharge from pump is clean, could also be a problem with any pressure tank, filtration tank, or water softener you have - either rusting out or not working properly

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13) another possibility is the chemistry of the deeper water is different (but not necessarily rusty by itself), and causing corrosion or algal bloom in your piping - again, unless a metal riser is corroding too, well discharge would be clean but rusty after it goes through your pipes (including any piping at the wellhouse or from well to house).

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14) could be "bedrock" has nothing to do with it - the deeper well might have encountered a different soil type that has different chemistry or source material, or you could have a stratified groundwater condition - the "clear" water you were pumping might be the surface water filtering down to the water table and forming a "clean" zone on top, whereas the "older" water at depth has lost its oxygen and gone anaerobic (common cause of iron or manganese staining) or picked up minerals from the soil, causing it to be "rusty" - which could make for a situation similar to near seacoasts where the "good" water "floats" on top of the slightly heavier "bad" salty water, so while a deeper well produces more water flow its quality might be poorer or totally unacceptable. This can also happen if you have seepage through a less permeable layer (bedrock or sedimentary overburden) from a deeper separate water table, which might be seeping poor quality water into the rainfall/snowmelt recharged surficial water table.

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Tracing which this is can be tough - comparing discharge straight from the pump with water at the house can rule in or out piping or treatment issues by determining if the rusty water is coming that way from the well or not. A Well and Pump contractor can pump out the well (or you might be able to using your pump if inflow capacity is low) to determine if the water flow cleans after the well volume has been diluted with inflowing water - that can determine if the source is bad or if something in the well itself is the problem. Then pulling the pump (if submersible) or foot valve and riser pipe (with above-ground pump) to inspect for corrosion, and running a camera down into the well (wet or dry after pumping out, depending on how opaque the water is) might identify whether it is corroding casing or screen or inflow of sediment (which would be filling in the bottom o fthe well gradually) or algal growth. Many sewer-cameras can go down a well next to the pump or riser pipe - though not in all cases - sometimes submersible pump has to be pulled to get down the casing. That could lead to a suggested remedy, though in many cases the first attempt does not solve the question.

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If your screen is long - reaches well up into the overburden over the rock (or whatever formation the well ended up in) commonly if you let the well sit a day or more without use so the natural groundwater flow flushes the well out and lets the water from different elevations statify in the well, you can then (in smaller casing wells commonly means pulling the submersible pumpbefore the sampling to provide access so requires well and pump contractor) use a bail sampler to sample the deep and shallower water (sampler has a "valve" which you open after it is at the depth you want, so you only sample the water at that depth) to compare them for "rustiness" and run water quality tests on them. Taking sample every few feet (at least for visual inspection) might identify a distinct variation in water quality at depth if the incoming water is the problem - which would then tell what depth the bottom of the well needs to be above (or what level the pump or inlet valve has to be well above if resetting inlet level to try that). Some contractors will try pumping the well out to test the water but that is less reliable unless done with a very small weighted (and measured) tubing, because using a high-capacityi pump or the well pump to draw the water down and sample it involves a lot of mixing in the well before the pump pulls it up. You need a sampling method that is minimally disturbing of any water quality layers in the well.

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If the well test showed good inflow and you have a high enough water table to provide enough water at a shallower depth, two possible solutions if you are looking at bad water at depth and good water higher up:

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a) shorten the well per above description of possible fixes at top of page

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b) if submersible pump, try a shallower pump or inlet valve setting depth IF the well has a long screen - so the pump would basically pull off water from the "top" of the screen or above and the rusty source water in the bottom would sit basically undisturbed in the bottom of the well. This is a cheap fix (usually less than an hour's work) that sometimes works - but the screen has to be open to both the bottom of the well (the bedrock ?) and also to enough of the upper presumably sedimentary layers to pull enough water from just the upper part of the screen - and the water table has to be high enough that the pump setting can be at or above the upper portion of the screen so it does not pull or mix in with the rusty water from below. Also, pulling from higher in the well reduces the well output you can use without having the pump run dry - because a shallow setting (closer to the water table) reduces the storage in the well available for the pump to draw on. This is critical in many wells - in some cases you might only get a small fraction of a gallon per minute inflow, but with enough well storage (from diameter and/or depth) in normal household usage (commonly less than 20-30 gallons heavy usage at a time) it can provide enough water for a normal household. Raise the inlet setting depth and you might be limited to a few gallons of storage and then just the inflow capacity - plus of course if you have seasonal water table fluctuations that also increases the chance of the pump going dry. If you try this you definitely want to put a "dry pump solenoid" on it, that shuts off the pump if it runs out of water.

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One other thing you could do initially - contact you county or state Geologist - or local Water Conservation District (or similar title) if you have one - about common water problems in your area. What you are describing might be old news to them - and in areas with water issues they commonly have data about wells in your area describving depth, soil conditions, water quality, etc that might tell you if this problem is prevalent in your area.

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Another professional source - a Groundwater Hydrologist or Geotechnical Engineer (commonly work for or as an independent consultant to a Civil engineering firm - not an Angies List category) to investigate and diagnose the situation.

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=======Depending on how much you trust the competence of your well driller, you could also consider talking to both him and to other Well and Pump contractors about your problem and see who comes up wioth the best sounding plan-of-attack for diagnosing and solving the problem.

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You also did not say WHY you put in a new well - old one contaminated, going dry, or what ? One possibility, depending on why it was abandoned, would be to put it back into service for domestic water even if not enough yield for watering uses, and use the new well only for irrigation and outside drive washing and such though of course that would require a bit of plumbing modifications, with two feed lines to the house, and two recirculation lines if you have those to prevent freezing. Also, you would have to be cautious about whether using the old well could draw contaminated water to it from the old one, if they are pretty close.

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If you want to respond back with more info or thoughts for a second response, you can do so using the yellow Answer This Question button right below your question - that keeps all the back and forth in this same "thread".

Answered 2 years ago by LCD




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