How to Install a Well Water Filter System: Placement, Drain, Power and Ground

Where everything goes

On a well, whole-house treatment goes after the pressure tank: Pentair says well-water systems “should be installed following the pressure tank”¹. Softeners go between the water inlet and the water heater, with any other conditioning equipment ahead of the softener². UV is the last piece of treatment equipment³. Pentair also asks for at least 10 feet of pipe between its softener and the water heater, so hot water can’t back up into the system¹.

1. Pressure tankstart here
2. Sediment filtersand, siltif needed
3. Iron / sulfur filterif neededif needed
4. Softenerhardnessif needed
5. UV lightlastif needed

Outside faucets can stay on untreated water, as Rheem and Whirlpool suggest^2,4. It saves salt, media and filter life on water used for the lawn.

Valves: shut-offs, bypass and sample taps

• Bypass. Every unit should be able to be isolated: Pentair asks for shut-off or bypass valves at the connections¹, and Rheem for its bypass valve or a three-valve bypass².
• Sample taps. VIQUA’s layout puts a shut-off at the main that also lets you sample raw water, with valves before and after the unit³. You’ll want a tap before and after treatment: Minnesota says to test the treated water after installing⁵.
• Plumbing first. Pentair says to make all changes to the house plumbing first and connect to the valve last, with lead-free solder and flux only¹.

The drain: air gap, never a direct connection

Backwashing filters and softeners flush to a drain. The rule every manual repeats: the drain line ends above the drain with an air gap, so waste water can never be siphoned back. Pentair: “Never insert drain line directly into a drain, sewer line, or trap”¹.

Drain requirements · by maker and code

Source	Air gap	Drain line
Pentair	2 pipe diameters or 1 inch, whichever is larger1	1/2 in minimum, 3/4 in over 20 ft1
Rheem	1.5 inches between hose end and drain2	Avoid runs over 30 ft or 8 ft high2
Clack (valve maker)	Air gap required	3/4 in if backwash over 7 gpm or line over 20 ft6
Ontario Building Code	Water treatment devices drain through an indirect connection7	See your municipality
Minnesota (reverse osmosis)	Air gap or approved air gap device; under-sink check valves not approved8	No saddle fittings on drains8

Also check the backwash flow your pump has to supply: the manuals list it, and a weak well pump can’t backwash a large tank.

Power and grounding

• Outlet. Pentair wants a grounded outlet that is always on¹; Clack, an uninterrupted outlet⁶. VIQUA requires a grounded outlet protected by a GFCI to comply with the National Electrical Code, plus a surge suppressor³.
• Grounding jumper. In some homes the electrical system is grounded through the metal water pipe, and a plastic bypass or valve breaks that path. Pentair calls for a same-material bypass or a grounded jumper wire across the equipment, and suggests consulting a licensed electrician¹. Rheem specifies a #4 copper wire clamped at both ends²; GE a 12-inch, 6-gauge copper wire with bronze clamps, not zinc clamps on copper pipe⁹.

Our take: this is the step people skip. If your house was built with metal water pipe, have an electrician check the grounding before you cut into it.

Licenses and permits

Rules vary. Minnesota advises hiring a licensed plumber or licensed water conditioning contractor⁵. Rheem’s manual notes that in Massachusetts a licensed plumber must be used². We found no province- or state-wide list of what a homeowner may install alone on a well. Call your local building department before you start.

After installing

• UV: chlorinate the plumbing after installing it, since bacteria already in the pipes stay there. See our UV guide.
• Test the treated water to confirm it works⁵.
• Write down model numbers, media and cartridge sizes, and the date: our filter change guide uses them.