Chlorine pellets are calcium hypochlorite tablets fed into a well casing by a dropper, and they are one of the two standard ways to chlorinate a private well continuously. The approach has real advantages over liquid dosing and a set of handling requirements that are not optional, because the material is an aggressive oxidiser in solid form.
How pellet feeding works
A feeder at the wellhead drops tablets into the casing on a timer or with pump cycles. The tablets dissolve in the water column, so disinfection happens in the well itself and the water is already treated as it is drawn. That gives long contact time without a separate tank, since the well column serves as the contact vessel, and it treats the casing and the pump as well as the water, which is why it suits wells with iron bacteria or a fouled casing.
The trade offs against liquid dosing
Dosing is less precise, because a tablet dissolves at a rate set by the water rather than by a pump you can adjust, so the residual varies more. Tablets can bridge in the feeder or fail to drop, which stops treatment with no obvious symptom. And you are putting a solid oxidiser into the well, which some jurisdictions restrict and which needs the right product: only tablets sold for potable well treatment, never pool chlorine, which contains stabilisers and other additives that do not belong in drinking water.
Handling and storage
Calcium hypochlorite is a strong oxidiser. Keep it dry and sealed, because moisture starts it reacting, and store it away from acids, ammonia based cleaners, organic material and anything flammable, since contact can cause a violent reaction or a fire. Never mix it with any other chemical. Use gloves and eye protection when loading a feeder, work in ventilated air, and keep it out of reach of children. Buy quantities you will use rather than storing a large stock through a damp season.
What still has to follow it
A filter to catch what the chlorine has oxidized, since dissolved iron, manganese and sulfide become particles. And activated carbon at the end to remove the residual and its taste before the taps. Check for a residual periodically at a tap upstream of the carbon, because that is the only proof the feeder is still dosing. The EPA notes private wells are not federally regulated under the Safe Drinking Water Act, so that monitoring is the owner's. Our well chlorination guide covers the whole system.
Questions people ask about chlorine pellets
Can I use pool chlorine tablets in a well?
No. Use only tablets sold for potable well treatment. Pool products contain stabilisers and additives that do not belong in drinking water.
What is the advantage of pellet feeding?
Disinfection happens in the casing, so the well column provides contact time and the casing and pump are treated as well as the water.
How should tablets be stored?
Dry and sealed, away from acids, ammonia cleaners, organic material and anything flammable, since contact can cause a violent reaction.
How do I know the feeder is still working?
Test for a chlorine residual at a tap upstream of the carbon filter. Tablets can bridge or fail to drop with no obvious symptom.