If you have a water softener in your O'Fallon home, you have probably noticed a valve or handle near it that you rarely touch. That is usually the bypass valve. Knowing where it is and what it does helps you handle a repair, a power interruption, or a visit from a service person without guessing.

What the bypass valve does

A bypass valve lets water skip the softener and flow directly from the main line into the home. Many setups use a group of valves, with an inlet valve and an outlet valve on either side of the softener, and a bypass valve that connects the two lines directly. When the inlet and outlet are closed and the bypass is open, untreated water goes to every tap. This is useful during maintenance, but it is not meant to be a long-term setting. On O'Fallon water, that means hard water running through your fixtures and appliances until you switch back.

Where to look

Start where the water line enters the house, which in many O'Fallon homes is a basement, utility room, or garage. Find the softener tank and follow the pipes running into its top or side. Trace the pipe that comes in from the main line. Along that run you may see handles, often labeled as inlet, outlet, or bypass. Some newer systems place a lever or dial on the control head itself, with settings such as service, bypass, and regenerate. If you cannot find the valves, check the manual or the label on the control head, since terms vary by model.

Before you touch anything

  • Keep your hands dry and check the floor for standing water.
  • Photograph the handles in their current position so you can return them to the same setting.
  • Move slowly. Older valves can stick, and forcing a stuck handle can damage a fitting.
  • Keep a bucket and towel nearby in case a connection drips.
  • If the valves are corroded, seized, or leaking, stop and call a licensed plumber.

Switching to bypass

Follow the steps in your softener manual when you have it. In general, close the inlet and outlet valves, then open the bypass. Once the bypass is open, run a cold tap and a hot tap in the kitchen to confirm that water is flowing. If flow is weak or stops, the bypass may not be fully open. Do not leave the home on bypass for an extended period, since the rest of the water system is designed around softened water and hard water can leave scale on fixtures and in water heaters.

Returning to normal service

Reverse the order. Open the inlet and outlet slowly, then close the bypass. Let the taps run until the flow is steady and any air has cleared from the lines. Check each valve connection for drips. Then confirm that the softener display is set to service and that the clock is correct, since an interruption in power can change those settings.

When valve position matters for testing

If you are collecting a water sample to compare raw water with softened water, the valve position is part of the record. A sample taken on bypass shows what your incoming water looks like, while a sample taken with the softener in service shows what comes out of it. Write down which way the valves were set when each sample was taken. Homeowners with private wells in the St. Charles County area can also use testing for coliform, E. coli, and iron bacteria through the MO State Public Health Lab, which offers low-cost or free options. Matching each sample to its valve setting makes the results easier to read later.

When in doubt

If a valve will not move, leaks, or you are unsure which line leads where, leave the handles as they are and get help. A plain photo, a copy of the softener manual, and a note of the current settings will make any conversation with a licensed plumber in O'Fallon faster and clearer.