[dukesjets]

We have a shore well on Lake Ontario which supplies the water for our home. Immediately after the water pressure tank, there is a 10" BB whole house filter, a UV light and a second 10" BB whole house filter. I have been using a 50 to 5 micron filter (Pentek DGD 5005) in the first BB and 1 micron filter (Pentek ECP1-BB1) in the second BB. After a period of 4 weeks, an odor began to fill the closet where the filters reside and the water coming out of the faucets and toilets began to smell as well. It smells like swamp gas. I replaced the filters and the odor immediately went away. The color of the filters removed from the BB were brown. I should mention that the shore well sits on a ledge of limestone. Any guesses to what is causing the odor? Should I be using different types of filters in this system? How long should I expect the filters to last (only 2 adults in the house)? Thanks.

[Andy CWS]

I have done a number of lake wells on Pelee Is. Each used a concrete cistern that lets lake water into either through a perforated pipe (reverse leaching) or a course-mesh screen, and water is then pumped into the house and enters its filtration/treatment system. Does that sound similar to yours?

If you have a cistern, has it been inspected for organic growth? Many cisterns are neither inspected nor maintained...out of sight, out of mind... Cisterns are an ideal place for organics to grow. Many organisms may be harmless but can cause odors and other water quality issues. Worse, animals--large, small and microscopic--can find there way into the cistern and live, reproduce and die. Cisterns should never be ignored.

Is this a full-time residence of a vacation setting?

All surface water treatment systems need to work differently than those of typical well waters. The reason is they can change from season to season and even day to day. The water will contain not only things like iron and hardness found in well waters but also a host of organic compounds, pollutants from commercial and residential sources, and natural run-off from rain and other natural events.

Your present system may not be adequate to handle your water. Can you describe the UV system by model/make? Do you know if it is a Class-A or -B system? Hardness and iron deposits on the quartz lens will cause 'shadowing' making the UV irradiation ineffective. UVs will have no effect on odors or other water quality issues outside of disinfection. How old is it and what is the flow capacity in gpm?

Your pre-treatment to the UV may require multiple units. The BB 10" DGD 5005 will clog up quickly, collecting those things that cause the odor you are describing. Changing them out will be constant and costly. Those filters will do nothing to prevent dissolved solids (iron, calcium carbonate, etc.) from passing through. I believe those are NSF certified depth filters and are effective at removing sediment to designated micron rating. But a UV needs more than just sediment removal to be effective.

I used a series of prefiltration including a screen filter (logs-n-frogs), followed by a 20-micron filter replaceable cartridge followed by a 3-5 micron backwashing filter/softener before the UV. This is then followed by a carbon filter and then an RO for drinking water.

I’ll stop here. I asked a lot of questions. Your water is treatable but must be done properly to avoid typical issues in surface water treatment.

Andy Christensen, CWS-II

There are also ozone systems that can be placed in the cistern for constant treatment against micro-organisms and to help precipitate soluble elements.

[dukesjets]

Thanks for the information (and questions) Andy. You're right about the cistern - out of sight, out of mind. I believe (the well was installed a year before we bought the house in 2006) that the water comes into the cistern via cracks or fissures in the limestone. Your understanding is spot on. I wasn't aware that the cistern needed to be inspected periodically but do believe that is causing our problem. I'll make some phone calls today to understand what is done in our area. This is a full time residence.

It's an ATS ultraviolet system approvimately 3 feet long. I just replaced the UV light in July and cleaned the glass (looked very clean and clear when I pulled it out). Not sure if it's a class A or B system.

Regarding the filters. Am I using a too fine a filter (50 - 5 and 1 micron)? If I recall correctly, there was a carbon filter in the second BB unit. I figured it was used to remove any odors coming in. Does a carbon filter do more than remove odor?

I did a home water test last Dec and the nitrates, hardness, etc all tested well within the guidelines. I also had a local lab perform a coliform bacteria test and the results were 0 in Dec 08.

Once I find out what is used to treat the cistern in this area, I'll update this thread. BTW, what is a log n frogs filter??

[Andy CWS]

LOL. Frogs-n-logs is just a screen mesh filter used to make sure large, visible object often found in surface water is prevented from entering finer filter and clogging them up quickly. They are easy to clean and cheap top replace if need be.

Some cistern owners use an ozone treament placed in the cistern to very effectively treat the water before entering the home and more rfined treatment equipment.
http://www.tripleo.com/process.htm
Some just use hydrogen peroxide or bleach and occsionally shock the cistern.

ATS is a well-known company. They make versions EV, SL and DWS/SE series. Does it say which version? NSF, Standard-55, Class A systems have fail safe devices that prohibit water passing to the user if the UV system fails or has interferring occurances, water clarity is not within allowances, bulbs are not producing the correct wavelength, etc. These are more expensive but they are more effective at producing safe water. Some places require only Class A systems, especially in public water treatment.

The 5005 filter is actually a very good design. The outer section has a courser mesh than the interior section. This allows it to take out larger particles without clogging the filter and then filters finer particles.

Carbon filters are excellent at removing a wide range of contaminants. Some carbon filters are recommended for VOCs (volatile organic compounds) which may include farming chemicals, etc., that a normal carbon filter cannot remove. Carbon filters like pleated or GAC (granulated activated carbon) are meant for clarity, taste and odor, primarlily.

I would avoid putting carbon filter prior to a disinfection system. They can be an ideal place for bacterial colonization--making incoming water worse, not better.

When you say "within guidelines", that makes me wonder who conducted the tests. Public health will say your water is fine even theough you may have horrible iron stains and really stinky water caused by hydrogen sufide. Their interst is safety, and iron is not considered unsafe, so...it is within their guidelines. Do you follow me on that? It is always best to have test results in numbers.

I would use an RO for drinking water purposes. As with most water treatment equipment, there are cheap units and excellent ones. This true with ROs as well.

Andy Christensen, CWS-II