Water Softener Bypass Valve: How to Use It
The bypass valve on a water softener sends house water around the softener instead of through it, so you can service, repair or shut down the unit without losing water to the house. In the service position, water runs through the softener; in the bypass position, it crosses straight from the inlet to the outlet and the house gets untreated hard water.
You'll use it when the softener leaks, when you're adding parts or cleaning the brine tank, and as a quick test when water pressure drops. Kinetico's troubleshooting advice uses the bypass exactly that way.
Where the bypass valve is
Look at the back or side of the control valve on top of the resin tank, where the pipes connect. On many homeowner softeners the bypass is a plastic or metal block bolted right there between the valve and the house plumbing. Pentair's Fleck bypass comes in a plastic version and a metal version with a lever.
If you don't see one on the valve, follow the pipes. Some installs use a loop of three separate ball valves instead: one on the line into the softener, one on the line out, and one on a crossover pipe that joins them.
Bypass valve positions: on, off, open or closed?
The wording confuses people because "bypass on" means the softener is off. Here's how the common styles read:
| Style | Softening (service) | Bypassed |
|---|---|---|
| Push-pull plunger or knob | Pushed in toward service, per the label | Pushed or pulled to the bypass side, per the label |
| Single lever on a bypass block | Lever toward the service mark | Lever toward the bypass mark |
| Twin knobs or handles | Both turned to service | Both turned to bypass |
| Three-valve loop | Inlet and outlet open, crossover closed | Inlet and outlet closed, crossover open |
Most bypass blocks have arrows or "service" and "bypass" molded into the plastic. If yours is worn off, find the model in the manual; don't guess. With a three-valve loop, close the inlet and outlet valves first, then open the crossover.
How to put a water softener on bypass
Find the bypass at the valve head or the three-valve loop.
Move it to the bypass position. On a three-valve loop, close the inlet and outlet, then open the crossover.
Open a cold tap. Water should run normally. It's now hard water.
If you're working on the softener, unplug the controller and relieve tank pressure before opening anything.
How to put it back in service
Plug the controller back in if you unplugged it, and reset the clock if the power was off a while. Pentair says outages over 8 hours may wipe the time setting.
Move the bypass to service slowly. Pentair's startup instructions say to ease it toward service so the resin tank fills gently.
When the flow stops, open a cold tap nearby to purge the air.
Make sure any separate bypass line is fully shut. Pentair warns not to leave a bypass line open with the unit in service.
If the softener sat in bypass for a while, run a manual regeneration before you rely on it again.
When to bypass a water softener
- A leak at the softener. Bypass first, then find the source. See water softener leaking.
- Maintenance. Cleaning the brine tank, swapping an injector or replacing O-rings.
- Pressure troubleshooting. Kinetico suggests replacing the pre-filter first, then putting the unit in bypass; if pressure comes back to normal in bypass, the softener is the cause.
- Any time the unit acts up. Pentair's user guide says to turn the valves to bypass if a problem occurs.
- Filling a pool or watering a big garden. There's no reason to spend salt on it.
When the bypass is the problem
If the water suddenly feels hard and the salt is fine, check the bypass. Kinetico says an engaged bypass is the next thing to check after salt. Pentair lists an open bypass as a cause of hard water too. Kids, cleaners and contractors bump them.
A bypass can also leak. On the Fleck valve, the bypass seals with O-rings, and Pentair says to use only silicone lubricant on them, so skip the plumber's grease from the junk drawer.
Replacing a bypass valve
Cracked plastic and leaking seals are the usual reasons. Pentair's Fleck part numbers are the plastic 60049 for 3/4-inch connections and the metal 60040SS (3/4-inch) and 60041SS (1-inch). Other brands, including Rheem, use their own bypass blocks, so get the part number from your softener's manual or the label on the valve before ordering.
The job: shut off the main, put a bucket under the valve, relieve the pressure, remove the clips or screws holding the bypass to the valve and the yokes, swap in the new one with lubricated O-rings, then turn the water on slowly and check for drips. If the new bypass won't line up with your plumbing, call a plumber rather than forcing it.
FAQ
How long can I leave my water softener on bypass?
There's no harm to the plumbing; you just get hard water. Leaving it off for a long stretch lets the controller drift out of sync with your water use, so run a manual regeneration when you put it back in service. Check your manual if the unit is on a day-override setting, since the control can be set to regenerate after a set number of days regardless of water use.
Will a water softener regenerate in bypass mode?
The controller doesn't know the bypass is turned. A metered control counts gallons that flow through it, so it won't see much use, but a time clock or day-override setting can still start a cycle on schedule. If you'll be bypassed for more than a few days, check your manual or put it back in service before the next scheduled run.
How do I bypass a water softener for an outside faucet?
You can't do it with the softener's bypass valve, because that switches the whole house. The fix is plumbing: tee the outdoor spigot line off before the softener. Penn State notes outside spigots can be left on hard water.
Is it OK to bypass a water softener?
Yes. That's what the valve is for, and Pentair recommends always having one so you can isolate the softener. The only cost is hard water while it's bypassed.
Sources
- PentairFleck 5600SXT Downflow Service Manual (opens in a new tab)
- KineticoFrequently Asked Questions (opens in a new tab)
- Penn State ExtensionWater Softening (opens in a new tab)
- PentairFleck 5600 SXT User Guide (opens in a new tab)
- PentairFleck SXT Control Manual (opens in a new tab)