PVC drain pipe check valve function: installation points to prevent sewage backflow

2025-08-19

Many families have encountered such bad things - the kitchen sink has just finished washing the dishes, and suddenly the sewage "gurgling" surges up, with food residues and unpleasant odors; the occasional dirty water from the bathroom floor drain, which stains the freshly mopped floor again. The source of these troubles is mostly the backflow of the drain pipe - when the whole building is draining at a peak, the sewage pressure in the main pipe is too high, and it flows back to your home along the branch pipe. At this time, a small PVC drain pipe check valve can help you "block" the problem outside the door.

PVC drain pipe check valve's core function is to be the "one-way goalkeeper" in the pipeline. It has a movable valve disc (usually made of rubber or plastic) inside. When your home drains normally, the pressure of the water flow will push the valve disc away, and the sewage will flow smoothly to the main pipe; but once the sewage in the main pipe wants to be poured back, the valve disc will automatically close due to the pressure of the water flow or gravity, strictly blocking the backflow of dirty water. For example, during the morning rush hour, the kitchen of the whole building is draining, and the water in the main pipe is "squeezed" badly. At this time, your check valve will immediately "close" to prevent sewage from drilling into your branch pipe.

However, for the check valve to work, the installation process should not be sloppy. First, choose the right model - the diameter of the check valve must exactly match your PVC drain pipe. For example, 50mm pipe diameter pipes are commonly used in kitchen sinks, 75mm floor drains are generally used in bathrooms, and 110mm sewage pipes are used in toilets. Be sure to measure the diameter of your own pipes before buying. If the model is wrong, either it cannot be installed, or there is a large gap after installation, or sewage will leak.

Then there is the installation location, which is the key to determining the effect of the check valve. The most reasonable location is the connection between your drainage branch pipe and the main pipe of the whole building - that is, the branch pipe is "almost connected to the end of the main pipe". For example, the drain pipe of the kitchen sink extends from the bottom of the sink to the branch pipe of the main pipe, and the check valve should be installed near the main pipe. If it is installed too close to the sink, the branch pipe in the middle will still store water, and the sewage will still flow into the sink during backfilling, which will not intercept it.

also has the installation direction, which must not be wrong! There are generally obvious arrow marks on the check valve, and the arrow points to the correct direction of water flow - from the branch pipe of your home to the main pipe. If it is installed upside down and the arrow points to your home, the valve disc will be pushed to death by the water flow during normal drainage, and the sewage will not be discharged. When backfilling, the valve disc will be flushed open, allowing sewage to flow directly into your home, completely losing its function.

After the installation is completed, be sure to do a sealing inspection. Before installing, check whether the rubber gasket in the check valve is cracked or aged. This is the core component to prevent water leakage. After installing, pour a basin of water and try it to see if the water can flow smoothly into the main pipe without getting stuck. You can also simulate the backflow situation: for example, plug the end of the main pipe with a rubber plug, and then pour some water into the branch pipe. If the check valve does not leak, it means that it is sealed.

Finally, don't forget to maintain it regularly. The check valve has been used for a long time, and it is easy to get tangled with hair, food residues and other sundries inside, which will jam the valve disc, resulting in lax closing. It is recommended to take it apart and clean it every six months, take out the dirty stuff inside, and check the sealing pad for aging - if the sealing pad hardens or cracks, quickly replace it with a new one, otherwise the check valve will "fail".

In fact, the PVC drain check valve is such a "small but powerful" device - it doesn't cost much, but it can help you block the most annoying sewage backflow. As long as you choose the right model, install the right location, and do a good job of maintenance, you can keep your drainage system at ease, and you will no longer have to fear the sudden emergence of dirty water and odor.


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