Water with NO odor has an odor AFTER osmosis filtering...

[john6428]

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 drink.

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 appreciated.

John, Bethel Acres, Oklahoma

[Don Phillipson]

This means you killed disease-causing organisms. It does not mean you removed smell-causing agents.

It appears you connected your RO system after summer storage without testing its performance beforehand. The maker can advise you better than anyone here.

[Oren]

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.

-- Oren

"Well, it doesn't happen all the time, but when it happens, it happens constantly."

[HarryS]

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 grow.

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 sulfide.

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.

Harry

[HarryS]

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.

Harry