How does a bypass valve work?

Table of Contents

• What does bypass mean?
• How do you set the valve to bypass?
• Normal operation

A bypass valve (or also: connection fitting, bypass fitting, 3-way valve) is required to connect a water treatment system. The connection could also be made without this fitting, but there are various arguments not to do this.

What does bypass mean?

The word bypass is mostly known from medicine. A bypass in connection with water basically means that a certain section of a pipe is bypassed. In the specific case of the bypass valve, it is possible to "bypass" the connected water treatment system. This can be advantageous, for example, if the device is defective or needs to be replaced. Without the bypass, the water would have to be turned off completely until the system worked again or was replaced. With the bypass there is almost no interruption in the water supply (assuming the water can be used without treatment).

How do you set the valve to bypass?

Such a valve usually has three taps that can be opened and closed. If all taps are closed, water will not flow through any of the outlets or inlets. If the middle tap is opened and the two outer taps are closed, the valve is on bypass and the water flows from right to left like a "normal" pipe (based on the picture).

Normal operation

During normal operation, the two outer taps are open and the middle tap is closed. If you also open the middle tap in this state, your water treatment system will be at least partially bypassed. Therefore, in this situation you should make sure that the middle tap remains closed.