Monday, October 22, 2012

How to Treat My Well Water for Coliform Bacteria

I just bought a home on well water and found out the well has coliform bacteria.  I understand I can use an ultraviolet light filter to kill the bacteria, or I can install a chlorinator.  My water has some iron in it, and occasionally we do get the rotten-egg sulfur odor..  Which type of system is best for my water?

Eureka, CA

Dear William,

There are a few options available for treating this situation, and the two most common are UV treatment and chemical treatment.  Ideally, to be certain you are achieving proper disinfection, we always recommend using both for a double barrier effect.  However, complete sterilization can be achieved with one or the other.  Either way, it is good to proceed with caution and plan accordingly.  I am including some more information on both options below.

First you should try to find out and eliminate the source of the coliform bacteria.  Check this link for more information:   You might also consider sanitizing the well and shocking with chlorine, and then re-testing the water for coliform bacteria.

To kill bacteria, the first and more common option uses chlorine injection with the use of a metering pump, which provides extra strength oxidation for coliform bacteria, as well as strong odors and high levels of iron and manganese (which can be linked with sulfur odors). 

The chlorine would then feed into a contact tank to provide enough time for the solution to react with the bacteria in the water, disinfecting it for good.   You could, as an option, send the water through a carbon filter to then remove the chlorine taste and odor completely.  Because chlorine injection maintains a regular residual of chlorine throughout the pipes of your home, it is the more reliable and safer method.

The second  method is a UV system for your whole house.  Ultraviolet sterilizers work by exposing the cell walls of an organism to intense UV light which disrupts the genetic material and prevents the organism from reproducing.  UV effectively destroys bacteria and viruses but is limited by the clarity of the water. UV only works on water that is clear and has a high UV transmission rate. Unlike chlorine there is no downstream residual disinfection. Pretreatment for iron, sediment and excessive hardness minerals is recommended.

Option 1: Chlorination

45MHP-10 Metering Pump & Solution Tank

Stenner Pump with 15 gallon heavy-duty polyethylene solution tank; Pump output 0.5 to 10.0 gallons per day (1.9 to 37.9 liters per day); voltage 115 or 220V; 60 Hz. This is a complete system that comes with everything you need: solution tank; metering pump; tubing; fittings; and injection check valve.

Excellent Warranty:  1 Year on the metering pump

40 Gallon Contact Tank

The CT-40 tank is a durable easy-to-install retention tank designed to provide optimum contact time during chemical treatment. These lightweight seamless totally non-corrosive retention tanks are ideal for new and replacement installation where durability is at a premium. 100% non-metallic polymer materials. Impervious to chemical attack.  Comes with  1-1/4 inch inlet.

2 sizes to choose from, same price  Either 16”Diameter  x 58”Tall or 21” 


(Optional) Carbon 7000 Backwash Filter for Your Home

Includes 1.5 cubic feet of Carbon filter media; and Fleck 7000 115v control valve.

All the filter media you need for the system is included. Excellent for use in de-chlorinating water and removing many tastes and odors.
Much longer life and higher flow rates than carbon filter cartridges.

Option 2: UV Treatment

S12Q-PA 120V 12 GPMSterilight UV Sterilizer S12Q-PA

·  Sterilight® point-of-use disinfection systems are specifically designed to treat microbiologically contaminated ground or surface waters.

·  These disinfection systems offer a 4-log reduction (99.99%) in bacteria, virus and protozoan cysts (specifically Giardia Lamblia and Cryptosporidium).
·  Drain port for reactor chamber flushing

·  Seven year warranty on reactor chamber for unparalleled protection

Dimensions: 3 inches diameter x 20 inches length.