The sink is an integral part of any outdoor kitchen design, and arguably, the most complex. One thing that you’ll need to keep in mind when designing an outdoor sink is how it will drain. In this guide, we’ll walk you through the various ways to design an outdoor sink drain, and help you decide which one is right for your needs. So, whether you’re just getting started with planning your outdoor sink or are looking for an upgrade, read on for everything you need to know about outdoor sink drains!
The best way to drain your outdoor sink is to have a plumber connect it to your home’s main sewer line that runs to the public sewer or your septic system. This can be achieved multiple ways.
For some, built-in plumbing can be a pricey and inconvenient option, due to budget or site constraints. But in the case of the outdoor sink, there is more than one way to achieve proper drainage. How you do it largely depends on your local building codes, your budget, and your needs.
Below are the most effective and common methods used for draining outdoor kitchen sinks, from fully plumbed and built-in to more temporary solutions that will have you prepping food for a bbq by next weekend.
Where To Drain an Outdoor Sink
So, where should you drain your outdoor sink? It depends on various factors. You should think about what works for you, what’s allowed in your location based on local codes and your budget. The size of your kitchen and how you use your sink are also critical considerations.
You can go as simple as placing a bucket under the sink. Or you can just ditch having to pull that bucket out of the cabinet by connecting the drain to the sewer or septic system, which is a more expensive solution.
Important: Prior to installing your outdoor sink, choose a solution and commit to it. Temporary solutions can seem cheap and smart in the beginning, but you’ll end up paying more than you originally intended to change it later.
Consider the Building Code
Your local building code is the most important consideration, whether you opt for a French drain or connect your drain to the sewer. Every jurisdiction has different rules for which drainage designs are acceptable and when a permit is required.
It is critical to keep your building code in mind when the time comes that you need to set your house up for sale. This is because if you need a permit but don’t get it, the house will not pass inspection.
And yes, adding plumbing can seem an expensive and time-consuming process, but it will save you headaches later on.
In many places, the building codes requirements call for outdoor sinks to drain to your septic system or a public sewer. What’s most important is that you check your local regulations for specifics.
One example of unique building code exceptions: If your state regularly deals with drought, (think California or Arizona), the local legislation may be ok with you using recycled water (greywater) for landscaping. In this case, you might consider the French drain method.
Three ways to find out your local building code requirements:
- Call your local building department. This is the most direct option and will likely get you a straight answer.
- Ask your contractor or plumber.
- Most building departments have the building code published on their websites. With a little digging, you can find the information yourself. Be warned that building code language is often vague and you may waste more time digging than if you had just called someone to ask.
Different Options for Outdoor Sink Drain
There are several ways you can drain your outdoor sink. Whether you want to understand what’s required in a fully plumbed or temporary setup, these are the most common.
Connect Drain To a Sewer
This is the built-in luxury option for an outdoor kitchen sink. But, despite requiring the most work, planning, and cost, it is the most comfortable of all the options we’ve mentioned. By connecting the drain to your sewer or septic system, you can use your outdoor sink as you would use your indoor kitchen sink.
With a drain line built in, you can even add a garbage disposal, which is integral to a modern outdoor kitchen design, especially when you wash dishes by hand. Plus, you can add an ice maker to your outdoor kitchen setup, which can drain into the same line as your sink.
However, there are some things to consider when planning a sewer drain line.
For one, running sewer drain lines is often laborious. Since drain lines typically need to drop 1/4-inch every foot, it’s easy to get caught below the line you need to connect to. So if your sink is located far away from your house, you may need to install a small pump to get the wastewater to its destination.
Again, you need a building permit and licensed plumber to do this, and depending on the location of your home’s main sewer line, this could be a costly endeavor. Also, if you live in a colder climate, your outdoor kitchen sink must be winterized to avoid burst pipes.
Dry Well Solution/French Drain
Whether or not you have a fully built-in sink drain, you still have to think about where that drainage goes. If your jurisdiction allows for greywater reuse, you might consider a dry well or French drain solution. The terms dry well and French drain are used interchangeably, but they’re actually slightly different from each other.
A French drain is a rigid tube that diverts water from building structures, avoiding damage in the long run. You’ll see them used often for downspouts and sometimes in landscaping to avoid standing water in low spots. See the photo below.
While they both drain into the earth, a dry well is built differently. It’s a bucket filled with gravel, then it’s buried 4 feet in the ground. The drain line runs into the top of it from your sink. They are fairly easy to install.
A dry well is a great option if your outdoor kitchen is separate from the house and far away from the septic line. Its simplicity of construction, low cost, and functionality also make it a smart way to water the landscape.
However, this solution might not be approved where you live, and you’ll also have to be more conscious about what goes down the drain, as greywater cannot include food scraps or a lot of soap, since those will either get stuck in the dry well bucket or soak in the ground where the soap doesn’t belong.
Use Under-Sink Bucket—A Large One if You May!
One of the easiest and most cost effective ways to drain your outdoor sink is by using an under-sink bucket. It doesn’t involve any plumbing. Just let the waste water drain into the bucket, remove it when it’s full and dispose of the wastewater into a septic system. Plus, it works in many locations, making it a popular choice for temporary solutions.
Besides being the cheapest option, the bucket works behind the scenes since you can hide it inside the cabinet. Depending on the quality of the water that the bucket collects, you might be able to reuse it for other things.
However, while this solution is quick and easy, if you have an ice maker, a bucket may not be enough. This is because those appliances use water, too. Also, emptying the bucket every time it gets full can be a tedious task.
Install a Self-Contained Lift Station
Another option that works hard behind the scenes. A self-contained lift station is completely hidden in the cabinet under the sink. It’s a one-stop solution that comes with two containers: one is for freshwater and the other for greywater.
These containers can be refilled or emptied when needed. The lift station runs on electricity but it can also heat water. It features a pump that delivers clean water to your faucet and the heater. Then, wastewater goes into a greywater tank.
But since fresh and greywater tanks use different connecting systems, the two containers cannot be combined.
By law, this is deemed a temporary solution and it can be a great outdoor sink drain option everywhere. It’s a bit arduous having to fill up the fresh water tank and empty the greywater tank, however, it is a creative solution for some with site constraints.
FAQs
Can I drain a sink outside?
Yes, outdoor sinks are designed for outdoor use, and they can be set up to drain outside. Connecting your sink to the home’s wastewater system should allow you to use the garbage disposal in it and use it similarly to your indoor kitchen sink. Draining your sink into a French drain or a dry well is perhaps the most common solution if you have a remote-located outdoor kitchen.
Does an outdoor sink need P-trap?
Every outdoor sink needs a P-trap. In fact, plumbing codes mandate the installation of a P-trap wherever there’s an open drain line that discharges sewage into a waste-vent system. The P-trap holds water, forming a seal that keeps stinky sewer gasses out of your kitchen.
How much does it cost to install an outdoor sink?
The overall cost depends on your design. You need to also factor in the cost of working with a licensed plumber and any digging and permits required.
Do outdoor kitchens add value to a house?
Building an outdoor kitchen is a serious investment. But experts believe that homeowners recoup the expenses when it comes time to sell their homes with a potential return on investment of 100% to 200%. So, yes, outdoor kitchens definitely add value to your property.
Which Option Works for You?
Placing a bucket under your outdoor sink may seem like the simplest solution, but are you willing to empty it every time?
If your budget allows, have the sink fully plumbed and connected to your home’s sewer line, so you can have hot and cold water for the sink, a disposal, and a water source and drain for your ice maker.
Whichever option you choose, having an outdoor kitchen sink is so luxurious. Food prep for outdoor parties will never be the same. Good luck on your design and install!
