Well Water Chlorination Systems

A. It can be, depending on your water chemistry. Chlorine injection costs little to set up, and you can test for a chlorine residual anywhere in the plumbing. With UV or ozone, the only way to confirm disinfection is to keep testing for bacteria. Shock chlorinate the well first (how to shock chlorinate a well), then let the chlorinator keep it clean.

A. Three parts: a metering pump with a solution tank, a contact tank that gives the chlorine time to work, and usually a carbon filter after it to take out the chlorine taste. A chlorine test kit confirms the residual. Unlike UV or ozone, you can check that it's working in a minute.

A. Enough to meet two needs. First, your water's chlorine demand: iron, manganese, sulfur, tannins and organics use up chlorine before any is left to disinfect. Second, the CT for disinfection: the chlorine residual (ppm) times the contact time (minutes). Cold water and high pH need a higher CT, so the right residual depends on your water temperature, pH and contact tank size. See the CT values chart. Neither changes the size of the pump. For most homes the smallest system works: adjust the pump's output or dilute the solution with water, then confirm the residual with a test kit. Send us your water test and we'll work out the numbers with you.

A. Chlorine is usually injected before the pressure tank, and the chlorinator runs only when the well pump runs. There are three ways to switch it on: wire it to the pressure switch (cheapest, needs wiring), use a pre-wired flow switch (no wiring), or use a proportional flow meter. The flow meter is the only option if you have to inject after the pressure tank or you have a constant pressure pump. The video below walks through all three.

A. Ultraviolet sterilizers and ozone systems. Neither leaves a chlorine taste or smell. That also means there's no residual to test, so you can't confirm disinfection without testing for bacteria. A UV or ozone system can go 6 to 12 months without routine maintenance. A liquid chlorinator needs its solution tank refilled every one to two months. UV and ozone usually cost more to buy and to run.

A. Generally, yes. Public health agencies want a small residual of free chlorine throughout the distribution piping, to kill bacteria that show up in the lines. UV and ozone leave no residual. We often use ozone as the primary oxidizer at the main holding tank, but we almost always recommend a slight chlorine residual as the final step.

A. Yes. A proportional flow chlorinator injects more or less chlorine as your flow changes, so it works on your own line after the pressure tank. If your water is clear and low in iron and manganese, a UV sterilizer at your house is another option.

A. High levels are. Low levels, like most city water, aren't acutely toxic. The long-term effects of low exposure are debated. If that concerns you, a whole-house carbon filter after the chlorinator removes the chlorine before it reaches the taps.

A. A pellet feeder drops chlorine pellets down the well each time the pump runs, so it can work when you have no room for a contact tank. It won't work if wire protectors or other obstructions block the pellets. To check, drop a few pellets through the access plug; you can usually hear them hit the water. Pellets cost more than liquid chlorine, so most of our customers use liquid injection.

A. Yes, if it's plain, unscented liquid bleach. Today that's 6–8.25% sodium hypochlorite, printed on the label. Don't use scented, splashless, color-safe or gel bleach; their additives don't belong in drinking water. Liquid pool chlorine (10–12.5%) with no additives works too, or NSF-certified chlorine granules dissolved in the solution tank.

A. Yes. pH, iron, manganese and turbidity all change the chlorine dose and the contact time. A full water analysis (general mineral plus bacteria) is the minimum we need to size a system properly. Order a water test.

A. Most private wells in the US and Canada have no disinfection, and waterborne disease outbreaks are rare. If your well is under ten years old, properly built with a sanitary seal, and tests negative for coliform, you may not need it. If it's older, has a cracked or missing seal, is shallow (under 100 feet), or takes in surface runoff, disinfect, or test regularly for coliform, especially in rainy seasons.