Hello - I have a well that has been flooded and has bacteria in it. I did a shock chlorination but it still tests positive for bacteria. I want to chlorinate this water until the area dries out and the well is back to normal. I have a ¾ HP pump and I think it pumps around 10 to 15 gallons per minute. Which type of chlorinator do you recommend?
Josh - sorry to hear about the flooding. Flooded wells can require some special care, please see our report on Floods and Well Water.
A liquid bleach injection system using a peristaltic metering pump and contact tank works very well. The goal is to have enough contact time and a sufficient chlorine residual for disinfection to occur. If the water is murky or has
color, iron or sediment in it, longer contact times and higher residuals are needed. Generally 1 to 2 ppm of chlorine with 10 minutes of contact time is sufficient to achieve disinfection.
You can easily control the chlorine residual with this type of system, and adjust to achieve the desired residual. It is best if you use a contact tank, as a pressure tank is on a Tee and will not provide the adequate contact time.
Each time the well operates, a small amount of chlorine is injected into the water. In the contact tank, bacteria is killed by the extended retention time provided by the tank.