P Trap Lower Than Drain Pipe- Why & Is It Legit?

Is the p-trap lower than the drain pipe of your house? Then you have got the wrong plumbing idea. Most sink traps people use in their houses or other residents are attached higher than the drain pipe. But what is the reason behind placing the p trap above the drainpipe?

If you have already placed your p trap of a sink or basin lower than the drainpipe, no need to be worried.

In this article, you will see the functions of a P-trap, how it works, and its placement with the drain entry. Though you have gone through some temporary problems, you will be able to solve them after reading this article.

P Trap Lower Than Drain Pipe- Is It Ideal?

Does p trap need to be below drain? Or is it ideal to have a p trap below the drain pipe of your house?

The answer is- No, it is not ideal to have a p trap piping lower than a drain pipe. The reason behind this is very interesting. If you have a slight idea about pressure, you will get it easily.

Water acts downwards due to gravity. In a p-trapping, the tiny particles that come with the water from a basin or sink get precipitated. They are reasonable for the clogging in the drain pipe, which blocks the normal water flow. When they remain precipitate, they break down and get washed away due to the water flow.

But when the p trap is placed lower than the drain pipe, the water gravity works first. As a result, the trap gets filled up first. When it fills up, then the water starts to drain away into the drain pipe. It happens because the water level on both sides needs to be equal at first. Otherwise, water will not flow from low to high levels.

What should you do if you have a p trap lower than a drain pipe?

You have already seen that it is not ideal to have a lower p-trap than the drain pipe. Now, we will go for its solution.

When you have a lower p trap, you need to change its position. Place the p trap above the drain pipe to ensure a smooth flow of water. Otherwise, the drainage of water will not be ensured properly.

First of all, we need to know about the minimum distance from p-trap to drain. According to the universal plumbing codes, the distance from the P-trap to the drain should be 24 inches or less. But what about the height adjustment of the o trap from the ground or sink/basin?

If you are using the trap for a basin then the height of the p trap should be within 26 inches to 30 inches above the ground.

The less the height from the ground, the more the pressure will be. But remember not to cross the drain pipe. Otherwise, the water will not be drained properly.

Place the sink or basin about 8 to 10 inches below the p trap. It is perfect to use the p trap 10 inches below from the basin or sink. Then connect it to the vent system. 

Tips: Don’t go for doing it yourself unless you have the basics. Go for an experienced plumber if you need to change the position of the p trap of the basin or sink of your house.

This Video Will Help You Too!

Frequently Asked Questions (FAQs)

Can you keep the P-trap lower than drain pipe?

No, P-trap can not be lower than the drain pipe because water gravity does not work upwards. Lower p-traps can cause some issues with plumbing.

Can a p trap be too low?

No, the p-trap can not be too low. If so, it will not provide drainage to the water.

What to do when the p trap does not line up with the drain?

When the p-trap piping does not line up with the drain, change the position of the trap under the tailpiece so that it properly keep up the level with both the tailpiece and drain.


Having a p trap lower than drain pipe will bring many issues in the drainage system of your house. So, check whether the p trap used in your house is lower than the drain pipe.

Bring the best plumber in your locality and fix it as soon as possible. I hope that you have got the right guidelines from us. For further problems related to plumbing, you can read other articles on our website. If you have more questions about it, you can comment below. Stay updated with our website.

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