A chlorinator pump is a small metering pump that injects a measured chlorine solution into a water line, either to disinfect a supply carrying bacteria or to oxidize iron, manganese and hydrogen sulfide so a filter downstream can remove them. Getting it right is mostly about three things: dose, contact time, and what happens after the chlorine has done its work.
What the pump has to do
Dose in proportion to flow, and only when water is actually moving. That is why the pump is wired to the well pump or triggered by a flow switch rather than run on a timer, so that a household drawing nothing is not receiving a slug of solution into a static line. The pump draws from a solution tank of sodium hypochlorite and injects through a check valve fitting into the pressure line. Adjustable stroke and rate are what let the dose be trimmed once the water has been tested at the outlet.
Contact time is not optional
Chlorine needs time in contact with the water to do either job, and the mistake that ruins these installations is injecting immediately before the filter or the tap. A contact or retention tank sized to give the required time at peak flow is part of the system, not an accessory. For disinfection the time is set by the concentration and by what is being killed. For iron and sulfide oxidation it is shorter but still real. A system without contact volume delivers chlorine to the house and treatment to nothing.
What comes after
Two stages, in order. A filter to remove whatever the chlorine oxidized, since dissolved iron converted to particles must be caught or it simply stains further downstream instead. Then activated carbon to remove the residual chlorine and its taste before the water reaches the taps. On a bacterial installation the carbon must sit after the contact tank rather than before it, or it will strip out the chlorine before it has done anything. The EPA notes private wells are not federally regulated, so this whole chain is the owner's to design and verify.
Living with one
Solution strength drops in storage, particularly in warm or bright conditions, so the dose drifts down over the life of a tank and needs checking rather than setting once. Test the residual at the outlet periodically and after every solution change. The injection check valve scales and blocks, which is the most common failure and shows up as a pump running with nothing being delivered. Keep the solution tank out of sunlight and heat. Where the only job is bacteria, ultraviolet is simpler and adds nothing to the water, and is worth comparing first.
Questions people ask about chlorinator pump
Why must the pump be tied to the well pump?
So chlorine is dosed only while water is flowing. A timer based dose puts solution into a static line and gets the concentration wrong both ways.
Do I need a contact tank?
Yes. Chlorine needs time in contact with the water to disinfect or to oxidize iron. Injecting just before a filter or tap achieves neither.
What goes after the chlorinator?
A filter to catch what the chlorine oxidized, then activated carbon to remove residual chlorine and taste, in that order after the contact tank.
Why has the dose drifted?
Hypochlorite solution loses strength in storage, faster in heat and light. Check the residual after each solution change rather than setting it once.