I filled a glass with water from my 5-stage osmosis filter and noticed
an odor. Not a familiar odor but certainly not something I care to
A little more info:
I purchased this home in May 2006. It has a water well, a deep well
system. The water quality test required by the mortgage company showed
no signs of bacteria. They only tested for bacteria.
The well water is clear and has no odor whatsoever. There is a slight
film of red sediment in the bottom of my water jug that I take to work
each day. The water tastes great. This water leaves no mineral deposits
on faucets or teapots, etc. The TDS is only 140 ppm. The soil in this
part of central Oklahoma is very sandy.
I have owned the 5-stage under-sink osmosis system for several years.
Until I bought this home in May it was used on a municipal treated
water system and worked great.
The pressure tank for the filter system was in storage during the
summer in a hot shed. I couldn't really fully drain or dry the inside
of the bladder tank so I was worried about what might be growing
inside. Before installing the system in my new house I sanitized the
bladder tank with a mild chlorine bleach solution.
I installed the system with new filter cartridges and it is working
great. The sediment filter turned red the very next day so I figure
I'll be changing the sediment cartridge more frequently.
It's been about two weeks and I just noticed the odor in the filtered
water. The unfiltered water from the well does not have any odor. I let
the filtered water run from the spigot for about 30 seconds and I could
no longer detect the odor. I ran most of the water from the storage
tank and let it refill. The next morning the odor was again present.
The TDS readings for the filtered water is still very low as would be
expected. The water is properly filtered it just stinks. This leads me
to believe that storage tank may be contaminated.
Most people use RO systems to remove odors. Mine is creating an odor
where there was none present! Your experiences or advice would be
Bethel Acres, Oklahoma
On 15 Oct 2006 08:36:53 -0700, email@example.com wrote:
Search for "rotten egg smell" and RO system". I change RO filters as
best as I can to the schedule. Can't speak t the well.
"Well, it doesn't happen all the time, but when it happens, it happens
From your description, it sounds like you have 'clear water' iron in your
well water. Clear water iron (soluble iron) doesn't show up in the water
until it has set in a container for awhile. Then you see a red film of
precipitated iron on the bottom of the container. Small amounts of iron
don't pose a problem in drinking water.
In some situations, dissolved iron can interact with certain bacteria in the
water (referred to as iron bacteria) to produce hydrogen sulfide gas (rotten
egg odor) from sulfur compounds occurring in the water. Getting rid of the
odor requires that you get rid of the bacteria. I'd guess that if the
bacteria have contaminated the ro system, they are most likely in the filter
housings before the ro membrane because the ro membrane will eliminate the
iron and bacteria from the water (providing it's still good and hasn't
developed a hole). The filters trap all kinds of solids from the well
water, so the filters and their housings are prime locations for bacteria to
I assume you changed your final filter? That should be an activated carbon
filter to remove tastes and odors and which should catch dissolved hydrogen
Another source of bacterial contamination is the faucet for the ro system
that you mount on the sink. The outlet end of the faucet is open to the air
and offers a place for bacteria to grow. It's a good idea to disinfect the
delivery tube of the faucet with a weak bleach solution every so often.
You should be able to isolate where the odor is being created. Turn the
valve off from your water supply to the ro unit. Let the system set for
awhile, drawing no ro water. Take the tubing off between the last filter
canister and the ro membrane and slowly turn the water valve back on to fill
a glass directly from the filter units and see if you get the odor. If not,
keep repeating the procedure through the other components in the system.
Eventually, you should be able to isolate the item causing the odor.
Another thing, if your system includes a DI (deionization) filter, be aware
that DI resin beds can cause an odor that I would describe as 'fishy'. The
resins don't normally produce this odor when new, but if they are old, i.e.,
set in storage for a long time or if the system was disconnected and stored
for a time, the 'fishy' odor can happen.
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