This guide describes common practice in the United States for planning purposes. Plumbing and electrical codes vary by state and city and change with each edition, so confirm the details with your local building department and hire a licensed plumber or electrician wherever your jurisdiction requires one.
A wet bar is a home bar with running water, which usually means a small sink, a supply line for an ice maker, and enough power for a refrigerator, lights, and a blender. All of it has to be planned and roughed in before the walls are closed, and the drain shapes the plan more than anything else. The layout advice in Gray Kangaroo's dimensions guide assumes you've settled where the water can go first.
The drain decides where the sink goes
Supply lines are small and flexible, so they can run almost anywhere. Drains rely on gravity. Small drain pipes are typically run at a slope of a quarter inch per foot toward the main drain, so a sink 12 feet from the nearest stack needs 3 inches of drop along the way, and that drop has to fit inside the floor, the wall, or the cabinet base.
Every sink drain also needs a trap and a vent. The trap holds water to block sewer gas, and the vent lets air into the system so draining water doesn't siphon the trap dry. Codes limit how far the trap can sit from its vent, and the limit depends on pipe size and on which plumbing code your area uses, since the International Plumbing Code and the Uniform Plumbing Code set different distances. Where a vent pipe can't reach, many jurisdictions accept an air admittance valve under the sink, a one-way valve that lets air in. Others restrict them, so ask before you design around one.
Bar sinks on an island or peninsula are a common snag because there's no wall to hide a vent in. Island fixture venting and air admittance valves are the two usual answers, and both depend on local approval.
Bars below the sewer line
Basement bars often sit lower than the pipe that carries waste out of the house. When the sink drain can't fall to the main by gravity, it needs a pump. A small drain pump made for sinks and laundry tubs can serve a bar sink on its own, while a sewage ejector basin set in the slab or a macerating upflush unit handles more fixtures. Pump systems need their own power and usually a vent and a check valve, and they make noise, which is worth knowing before you put one under a bar where people sit.
The small-space remodel article weighs the same choice for closets and stair voids, where a bus tub under the counter can be a better trade than a pump. A dry bar with no sink at all is a reasonable choice too, especially when the kitchen sink is a few steps away.
Water supply for the sink and ice maker
Supply lines for a bar sink usually tee off the nearest hot and cold lines, run in PEX or copper, and end at shutoff valves under the sink so the faucet can be serviced without shutting off the house. An undercounter ice maker or a refrigerator with a dispenser needs a cold line of its own, commonly quarter-inch tubing from a dedicated valve. Many manufacturers recommend an inline filter on that line, which also cuts down on scale inside the machine.
Most undercounter ice machines also need a drain for meltwater, either by gravity to a floor drain or standpipe or through a model with a built-in drain pump. Check the installation manual before you finalize the cabinet layout, since the drain connection is often at the back of the unit and low to the floor.
Circuits and outlets
Appliance manuals list their electrical requirements, and many undercounter refrigerators and ice machines call for a dedicated circuit. The building article recommends two dedicated 20-amp circuits as a starting point, one for refrigeration and one for small appliances and lighting, which suits most bars with a fridge and a blender. A bar with an ice machine, a beverage center, and a glass washer may need more, so add up the loads from each manual before the electrician quotes the job.
The National Electrical Code requires ground-fault (GFCI) protection for receptacles within 6 feet of a sink in a home, and recent editions extend it to more receptacles in kitchens and basements. States and cities adopt code editions on their own schedules, often years behind the newest one, so the rule that applies is whatever your jurisdiction enforces. Recent editions also require the GFCI device to be readily accessible, so put the reset button on a cabinet face or backsplash where you can reach it once the refrigerator is in place.
Plan outlet locations around the equipment. A refrigerator or ice machine usually plugs in behind or beside the unit, a blender and any countertop machines need receptacles along the work counter, and a low-voltage lighting driver needs power in a spot you can get to later.
Low-voltage lighting
LED tape under shelves and inside cabinets runs on 12 or 24 volts from a driver that converts household power. Drivers need some air around them and have to stay accessible for replacement, so they belong in a cabinet or behind an access panel, never sealed inside a finished wall. If you plan to dim the tape, the driver and the wall dimmer have to be compatible, and the lighting guide covers those choices.
Permits, inspections, and who does the work
New plumbing and new circuits generally need permits. Many jurisdictions let homeowners pull permits and do the work in a house they live in, while others require a licensed plumber or electrician for some or all of it. On most builds the order runs framing, plumbing and electrical rough-in, a rough-in inspection with everything exposed, insulation and drywall, cabinets and the top, then the sink, faucet, devices, and a final inspection.
Skipping permits saves time up front and can cost more later. Unpermitted work can complicate an insurance claim or a home sale, and an inspector may ask to open walls to see what's inside. If the bar shares a wall with a bathroom or kitchen, ask the plumber to look at tying into those lines before you settle the layout, since a short connection to an existing stack often decides whether a sink is easy or a project of its own.