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Plumbing a new kitchen

How to

If you’re installing new kitchen plumbing, careful planning can save a lot of trouble and additional cost. Where do you want appliances that need a water supply? Would you like a garden tap plumbed in from the kitchen? Whatever you want, make sure you’ve thought about how you can achieve it with the available space and budget.

Plumbing should be installed before any wallpaper, fixtures or cabinets are installed. This makes it easier to make changes during the planning and in the earlier stages of installation.

The kitchen plumbing you install now will also determine how easy it will be to make changes in the future. So if you think there’s something you may want later down the line, think about what plumbing would be needed.

Before you start plumbing

  • If you live in a flat, check if you need freeholder or management company consent for the work
  • Plumbing is much simpler if your sink and washing machine is in the same place. If not, think about the route the pipes will need to take. Keep it simple with as few connections as possible
  • If you’re fitting a sink into an island, you’ll need to work out how the pipes for water and waste will be concealed in the floor
  • Know your water pressure. Some kitchen taps and washing machines need a minimum pressure to work
  • Many kitchens house all plumbing elements on the same wall. This is known as a wet wall. Plan your new kitchen with this in mind and if you want an American-style fridge with an ice maker, it’ll need a water supply too

Pipes and pipework

All kitchens need a hot and cold water supply and a waste pipe for dirty water. Waste pipes should be 40mm in diameter and positioned so they slope away from appliances, towards the drainage point. The slope should be just enough so the water doesn’t flow back into the appliance.

Try to locate pipes inside cupboards rather than behind them, as this will allow units to sit flush. If you’re moving or modifying any pipework, try to keep bends to a minimum—this will help water flow freely. Gas pipework should only be moved by a professional.

Running supply pipes

Along walls

The simplest way of running new pipework is to clip the pipes to walls. Try to keep them neat and parallel. Conceal them with plastic ducting, box them in or install false skirting. If you’re building a stud partition wall, run pipes through the studs and noggins before closing the cavity.

Under a suspended floor

You can either clip pipes to the side of a joist, support them on battens attached between joists, run pipes through shallow notches cut into the top of the joists, or pass pipes through holes drilled into the joists.

Keep pipes at least 50mm below the top of joists to avoid any potential damage from nails and mark pipework on the boards to remind you of how it runs. If you’re cutting into joists, remove as little timber as possible as joists are critical to the building’s structure.