A chlorine injection pump doses a measured hypochlorite solution into a well line, either to disinfect water carrying bacteria or to oxidize iron, manganese and hydrogen sulfide for a filter downstream. The pump itself is straightforward. The parts of the system people leave out are what decide whether any of it works.
Tying the pump to actual flow
The pump must dose only while water is moving, which is why it is wired to the well pump or triggered by a flow switch rather than run on a timer. A timed dose puts solution into a static line when nobody is drawing water and delivers nothing when the household is. Adjustable stroke and rate let the dose be trimmed once the residual has been measured at an outlet, and that trimming is done after commissioning rather than assumed at installation.
Contact time is the component people omit
Chlorine needs time in contact with the water to disinfect or to oxidize, and injecting immediately before a filter or a tap achieves neither. 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 needed depends on concentration and on what is being killed; for iron and sulfide oxidation it is shorter but still real. Without contact volume, the household receives chlorine and no treatment.
What has to follow it
A filter to remove whatever the chlorine oxidized, because dissolved iron converted into particles must be caught or it deposits further down the plumbing 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, never before it, or it strips the chlorine out before it has done anything at all. Order matters as much as selection here.
Keeping it working
Hypochlorite solution loses strength in storage, faster in warmth and light, so the delivered dose drifts down over the life of a tank and needs testing at an outlet rather than setting once. Keep the tank out of sunlight and mix to the same strength each time. The injection check valve scales and blocks, which is the most common failure and shows as a pump running with nothing being delivered. Our chlorine injection guide covers sizing the contact tank.
Questions people ask about chlorine injection pump for well water
Why must the pump be tied to the well pump?
So solution is dosed only while water flows. A timer based dose puts chlorine into a static line and misses actual demand.
Do I really need a contact tank?
Yes. Chlorine needs time in contact to disinfect or oxidize. Injecting just before a filter or tap achieves neither.
What order do the stages go in after the pump?
Contact tank, then a filter to catch what was oxidized, then activated carbon to remove residual chlorine and taste.
Why has the residual dropped without me changing anything?
Hypochlorite loses strength in storage, faster in heat and light. Test at an outlet after every solution refill.