How to Install a Chlorine Injection Pump

Turn off the water supply and depressurize the line. Verify your chlorinator certification matches your application (NSF/ANSI 61 & 372 for drinking water). Have the manual open beside you, along with the bypass schematic and bill of materials from Steps 2 and 3.

Pick a location close to your water source, accessible for future service and chemical refills, away from freeze risk in northern climates, and within 4 m vertical lift of the chlorine solution tank (the D14WL and D40WL self-prime up to 4 m). Make sure the water flows in the direction shown by the arrows on the unit body. 

• Indoor mechanical room, well house or pump house: preferred — protected from weather
• Within reach for annual seal-kit service and weekly solution refills
• Above the solution tank, not below — the unit draws solution upward by suction
• On the main service line downstream of the well pump and pressure tank, upstream of any sediment or carbon filtration
• Away from local plumbing code violations — verify with your jurisdiction

A bypass loop is the single most important upgrade over a basic in-line install. It lets you isolate and service the chlorinator without shutting off water to the entire building. The bypass loop is a parallel pipe with a third valve — open the bypass, close the two unit-side isolation valves, and you can pull and service the chlorinator while water still flows to the house. 

1. Turn off the main water supply to the area where you'll be working and depressurize the line.
2. Cut the water supply line at the chosen installation point — use a pipe cutter for a clean square cut.
3. Install the upstream and downstream isolation valves, and the bypass valve.
4. Connect the Dosatron unit between the two isolation valves, with the flow arrows pointing in the direction of water flow.
5. Use NSF-listed thread sealant on every NPT joint. Hand-tight plus 1–2 turns with a wrench is typical — do not over-torque plastic fittings.
6. Connect the suction tube to the unit's suction port. Lower the weighted strainer into the chlorine solution stock tank, all the way to the bottom.
7. Install the injection check valve at the point where the unit's outlet meets the main line. The arrow on the check valve must point in the direction of water flow.
8. Mount the unit vertically and plumb on the mounting bracket. The unit must be in the vertical orientation to dose accurately.
9. Fill the solution tank with chlorine solution (sodium hypochlorite or pre-mixed calcium hypochlorite). See the Sodium vs Calcium Hypochlorite guide.

Open the upstream isolation valve slowly. Open the downstream isolation valve. Set the injection ratio on the unit dial — use the Chlorine Dosing Calculator to compute the right ratio for your target ppm, NaOCl strength and stock-tank size. 

1. Open a downstream tap and let water run for 2–3 minutes to prime the chlorinator. 
2. Listen for a steady 'click' (or feel the pulsations on the body) — that's the hydraulic motor stroking.
3. Take a DPD test or test-strip free chlorine reading at the closest tap downstream of the contact tank.
4. Compare to your target residual. If too low, increase the injection ratio (e.g., from 1:1500 to 1:1000). If it is too high, decrease it.
5. Take a second reading at the furthest tap on the distribution system — this is the worst case for residual.
6. Document the readings for your operations log.