Do Double Sinks Need Two Traps? (Explained)

It becomes difficult to do plumbing when we don’t know everything which helps to fit or fix the draining system with our sinks. If you’re struggling to build out your double sink drain system, you might need more in-depth knowledge.

In this article, we described do double sinks need two traps, and how many traps are fine for double sinks. Using the right number of traps makes your work easier.

Double Sinks only need one trap, single trap pipe vents water fine into the draining system. When we try to add double traps then the chances of drainage issues increase. Two traps cause the air to travel up when the water flows down and it results in no drainage ventilation issues.

When non-technical people try to plumb it themselves, they make some mistakes and those mistakes confuse them with simple fixing.

Do Double Sinks Need Two Traps

Is One Trap Good For A Double Sink?

We approached expert plumbers and kitchen designers to get the right answer to this question. In our research, we found good suggestions and tips from them.

The expert plumber said, “we recommended to our customers to use only one trap for their sinks, it does not matter whether the sink is double or single type.” This suggestion said a lot in itself.

Some Experts said, “One trap is fine. But if you want to use two traps then use one to sink and the second to the floor.  You need weir size perfect, but make sure P traps are not double trapped”.

The sum of our research: One trap is suitable for a double sink. If you don’t know how to plumb your traps, wiring a plumber is the best decision. So you can’t face any ventilation issues in the future.  If you don’t afford a plumber’s fees, try to do it yourself by following the trap fixing guide.

In the next section, you will learn how you can trap a double sink yourself. If you do the plumbing work without any help from a plumber then you will save your money. 

But if you aren’t able to follow these steps then make sure you can hire a plumber for your double sink trap fitting.

What Happens If You Have Two P Traps?

Ventilation is an essential matter for all homeowners. It becomes difficult to work in the home if the ventilation system is done incorrectly.

If you have two P traps for your sink then it will cause drainage issues. Two traps are not best for fast and proper drainage. If there are two p traps for a sink, the air becomes trapped between them. As we know air is lighter than water which will cause the air to travel up as the water flows down in the drain and this will develop no drainage issue.

No one wants to have challenging situations while using sinks or toilet seats. Proper plumbing is very important for a house. 

If we don’t have the right and required plumbing system, it will make it tough to do activities with the help of sinks, seats, and bathtubs.

But what if you want to have 2 P traps in your house? The answer is below:

Some people use two traps in their house which is fine for them because they have a proper slope and a vent within a certain distance of the drain.

You can use two P traps to the single drain, but only when the slope and vent are in the right position for the drain of your house.

How Many P-Traps For Double Kitchen Sink?

A Fixture arm is the main pipe where we connect the P trap for the sink and it’s a special pipe that allows multiple sinks to drain water into it.

We can only use one trap per one fixture arm, Each trap needs its separate fixture arm which means you can use more than one trap for a double sink.

A double kitchen sink requires only one trap to work fine, there is no need to have more than one P trap in multiple sinks. Sink water goes down to the drain with help of the Fixture arm and A P trap. We can’t fix more than one P trap on a single fixture arm. If you try to connect two P traps then it results in no drainage issue.

This is also the same for the bathroom double sink. Bathroom double sinks also require only One P Trap.

If you already have two traps and you’re facing drainage issues, try to use only one trap instead of two.

The cost of fixing drainage issues depends on the scale of drainage, it will cost $500 for small-scale fixes to $18,000 for full-scale solutions. Make sure you’re using the right no of traps to avoid high draining issue fixing costs.

Double Sinks need only under 30 inches of the tailpiece(outlet) to use a single trap. If the outlet centerline is more than 30 inches then using a single trap is difficult.

Is One P Trap Enough To Use Double Sink?

People who don’t know how the drag system works are always confused during fixing or plumbing any part of the home drainage system.

One trap is enough to use a double sink. Water and other soap waste will flow easily with a single trap. If you try to add more than One P trap to the double sink, it will result in drainage issues. One p trap works well and has proven to avoid ventilation issues.

Two sinks can share one P trap, but they require the centerline of the outlet (tailpiece) of both sinks under 30-inches horizontally from the trap centerline. 

You cannot use a single trap for double sinks If the centerline of the outlet of both sinks is more than 30 inches from the trap centerline.

Can 2 Sinks Share The Same Trap?

Most kitchens and bathrooms have more than one sink. If you also have a double bowl sink and you want to start using it, you need to know some essential ventilation factors.

Two Sinks can Share the same trap, there is no requirement to add more than one trap to two sinks. Just take the centerline of the outlet 30 inches horizontally from the trap centerline. It will avoid drainage issues.

Most people have a space issue below the sink, they want to save space by minimizing traps. 

A plumbing code says that we can use two traps at certain distances but the reality is different. It will develop positive pressure issues with two traps.

Final Thought

You have to use only one trap for a double sink, if you try to use more than one trap it will cause serious drainage issues.

The fixture arm down to the sink needs only a single trap, the fixture arm perceives water, and water from the sink travels through the fixture arm to the drain.

If you don’t know how to plumb, hiring a good plumber is the best to avoid issues during the plumbing of traps.