There are two common ways to chlorinate a private well continuously, and they differ enough in operation that the choice shapes the whole installation. One drops solid tablets into the well casing, the other injects a liquid solution into the line. Both work, and they suit different wells and different owners.
Pellet or tablet droppers
These sit at the wellhead and drop calcium hypochlorite tablets into the casing on a timer or with pump cycles, so the disinfection happens in the well itself and the water is already treated as it is drawn. That gives a long contact time for free, since the well column is the contact tank, and it treats the well casing and pump as well as the water. The trade offs are less precise dosing, tablets that can bridge or fail to feed, and the fact that you are putting solids into the well, which needs care and is not permitted everywhere.
Liquid injection systems
A solution tank, a metering pump triggered by the well pump or a flow switch, a static mixer, a contact tank and a carbon filter afterwards. Dosing is precise and adjustable, the residual can be verified downstream, and the whole system is above ground where it can be seen and serviced. It is more equipment and more maintenance: solution to mix and keep fresh, an injection point that blocks, and a contact tank that has to be sized for peak flow rather than average use.
Which suits which well
A tablet dropper suits a well with iron bacteria or a fouled casing, because treating in the well attacks the growth where it lives, and it suits owners who want fewer components. Liquid injection suits a household needing consistent, verifiable dosing, a well where adding solids is unwelcome or not permitted, and any installation where the oxidation of iron and manganese has to be controlled precisely ahead of a filter. Local rules on well treatment are worth checking before choosing either.
What both need afterwards
A filter to catch what the chlorine has oxidized, since dissolved iron, manganese and sulfide become particles. A contact arrangement adequate for the peak flow, which the well column provides for a dropper and a tank must provide for an injection system. And activated carbon at the end to remove the residual before the taps. The EPA notes private wells are not federally regulated under the Safe Drinking Water Act, so testing for a residual and for bacteria is the owner's. Our well filtration guide covers the train.
Questions people ask about chlorinator for well water
What is the difference between a pellet and a liquid chlorinator?
A dropper feeds tablets into the well casing so the well provides contact time. A liquid system injects solution into the line and needs a contact tank.
Which is better for iron bacteria?
A dropper often, because treating in the casing attacks the growth where it lives rather than only the water drawn from it.
Which gives more control?
Liquid injection, since the dose is adjustable and a residual can be measured downstream to confirm it.
Do both need a filter afterwards?
Yes, to catch the iron, manganese and sulfur the chlorine oxidizes, and carbon at the end to remove the residual before the taps.