Can I Install a Dishwasher Without a Sink in an Island?
A dishwasher can be installed without a sink, though it makes it a bit more difficult of a project. Without a sink nearby, separate supply lines for water will need to be run to the island, and a separate drain will need to be laid out. Additionally, many local building codes require that dishwasher drains be ventilated. An island dishwasher will need to have a separate air vent for its drain.
Without a sink to tie in to, an island dishwasher will need to have water supply lines run out to it. This may necessitate gaining access to the crawlspace or basement, and will require hot water be run out to the island from your hot water heater. Some dishwashers can heat their own water, and if access to cold water is more readily available, these models might be preferable.
The island will require an electrical outlet that is rated for at least 20 amps. Care should be taken to check the manufacturer's website or the manual for your specific model to ascertain the electricity requirements before attempting an island installation. Additionally, many larger capacity or commercial dishwashers require a dedicated circuit.
Distance from Sink Drain
A dishwasher can be installed and tied in to a sink drain despite being in an island. Typically the user manual for a dishwasher model will outline how far a unit can be installed from a sink and still be tied in to the drain. Dishwashers have discharge pumps, meaning their water is forcibly ejected from the unit, which extends the distance that you can run the drain hose. Remember, however, that an island dishwasher will need to have its distance measured taking in to account the drain hose being placed under the floor.
Ventilation: Island Loop Vent
The dishwasher will need to have its drain pipe vented to ensure smooth flowing of waste water. In an island, where there is no easy tie-in to a sink vent, an island loop vent will need to be employed. An island loop vent is essentially a length of pipe that loops under your counter top as high as possible, to provide as much air as possible to the drain. The loop vent will be tied in to the sink vent through piping laid under the floor.