Installing Outdoor Kitchen Plumbing

Plumbing For An Outdoor Kitchen

Most people want a grill on their deck or patio. Adding a small sink nearby helps with food preparation and reduces trips in and out of the house. Plus, a gas barbecue unit that's built into a tiled countertop gives the cook plenty of convenient cooking and prep space.

Construct the cabinets and countertops to resist weather. Unless you live in a very dry climate, provide an awning or some other shelter from rain so the outdoor kitchen is at least partially protected.

If you have freezing winters, install plumbing that can be drained in the fall. Be sure you can shut off water from inside the house. The drain line shown here runs to a simple dry well and needs no venting. It is acceptable for the graywater that a prep sink produces.

Prestart Checklist

Time
A day to run plumbing and a gas line for a sink and barbecue

Tools
Groove-joint pliers, screwdriver, level, shovel, posthole digger, hole saw, tools for joining copper and plastic pipe

Skills
Installing PVC drain pipe, installing a sink, running supply lines

Prep
Plan the location for your sink and barbecue; build the cabinet

Materials
Sink, gas-fired barbecue, supply pipes and fittings, drain pipes and fittings, trap, garbage can, gravel

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Step 1

From inside the house, run supply pipe designed for outdoor use. Slope the pipes slightly to help them drain. Install shutoff valves with drain plugs at the lowest point. Attach the pipes firmly with two-hole clamps every 4 feet or less.

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Step 2

Run the supply pipe through the house wall and to the outdoor kitchen, routing up through the bottom of the sink/grill base cabinet. Sweat male threaded adapters to connect with the supply tubes for the sink.

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What If... The outdoor kitchen is a long way from the house?

As an alternative to bringing hot water all the way from the house, install a hot water dispenser. This simple plug-in unit fits easily in the cabinet. With it, you need only run a cold water line outdoors; a saddle tee and branch line run to the dispenser. It is designed to supply nearly boiling-hot water, but you can turn the thermostat down to 140 degrees, which is within the range of normal hot tap water.

You will have to run 120-volt GFCI-protected electrical line to the unit; use only outdoor cable.

Step 3

Install a PVC drainpipe and adapter for the sink trap. To supply a barbecue with natural gas, run pipe that is code-approved for exposed outdoor gas lines in your region. Some barbecues may require a gas regulator. Install the sink and trap.

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Choosing the right materials

Codes for outdoor plumbing can vary widely from area to area (and even from one town to the next), so check with your local building department before buying any pipes and fittings.

Among the options for supply pipes, PEX and CPVC are easy to run. If you install copper pipe, choose Type L or K, which are thicker and stronger than Type M.

PVC is the standard choice for drainpipe. You may want to run perforated drainpipe underground; this will allow some water to percolate out along the way to the dry well.

Gas pipe options include aluminum composite pipe, and certain types of copper, green-coated steel, galvanized steel, and schedule 80 PVC (which is stronger than standard schedule 40).

Step 4

Dig a hole for a dry well at least 10 feet from the patio or deck (check local codes). Dig a trench to it that slopes down and away from the house. Run the drain line -- 1-1/2-inch PVC probably will be acceptable -- in the trench. Check that it slopes at a rate of at least 1/4 inch per foot.

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Step 5

Punch or drill a grid of holes, about 1/2 inch wide, in a garbage can. Set the can in the hole; its top should be 2 inches below grade. Mark where the pipe will enter and cut a hole for the pipe. Set the can back in the ground, install the pipe into the hole, and fill the can with coarse gravel.

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