How to Plumb In a Dishwasher

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The struggle of dealing with a poorly performing dishwasher can be draining, especially if you find yourself having to manually rewash the dishes even after they have been through the dishwasher. So, you decide to upgrade your dishwasher to a better, more powerful version that has no problem tackling even the most stubborn of stains. However, before you can get your dishes sparkling clean with the help of your new machine, you’ll first need to figure out how you are going to plumb it in – either with the help of a plumbing professional or by having a go yourself. Whether you are revamping your kitchen or replacing a worn-out appliance, installing a new dishwasher is a task that you easily accomplish yourself with the right tools and guidance, even if your kitchen has never been fitted with one before. This guide will help you to choose the right location for your dishwasher and install or replace an old one, with a new appliance. Our safety tips will also help you to stay safe whilst plumbing in a dishwasher and make sure your work complies with current plumbing regulations.


There’s lots of useful information to find in this article to help you get your new dishwasher installed and up and running. See a list of all the sections we’ve included below!

Should You Hire a Professional?

If you’ve never plumbed in a washing machine before it can be daunting and you may be considering hiring a professional plumber to do the job for you. A plumber may be able to get the job finished quickly and efficiently but the price for doing so could be far above your budget. In the United Kingdom, a plumber will typically charge around £40-50 per hour and often there is a call out fee added on top. When looking at a couple of hours of work, this could drive up your installation fee to a couple of hundred pounds at least. If you have the time, patience, and tools to install the dishwasher yourself you could potentially save yourself a lot of money. When hiring a professional you will also need to take the extra time to read reviews and shop around so that you can be sure to get the best value for money, this all adds up to extra time in getting the job done. Also, remember that you can always call upon a plumber for advice or even to take over the job if you find plumbing in the dishwasher yourself is too difficult – but why not give it a go first? We have listed all of the steps and tools you’ll need below in an easy to follow format.

Safety Tips Before You Get Started

All DIY work involves an element of risk, so ensure that you stay safe by following our DIY safety tips. Take time to read them through before you get started on installing your dishwasher.

Safety Tips Before You Get Started

Before you get stuck into a DIY task you should avoid wearing loose-fitting clothes or jewellery that could get caught. Also, make sure that your workspace is clean and tidy and that you have enough time to finish the task at hand without rushing. Once you’ve accomplished your task, always remember to tidy up afterwards and store your tools safely. If you are working inside and using hazardous chemicals make sure the room you are working in is well ventilated. Tools and Equipment DIY jobs often require the use of different tools and equipment and its important to ensure you are using the right tools safely. If you need to use a set of ladders always make sure they are placed on a stable, level surface. If you are using A-frame ladders make sure they are locked in the open position, and if you are using a leaning ladder allow for a 1 foot spread at the base for every 4ft of height. Also, remember to never use aluminium ladders near electrical wires. If the job requires specific tools, familiarise yourself with how to operate them safely before using them. If any of the tools need repair or maintenance work, check that they are switched off and unplugged before changing parts or taking the tools apart. Always make sure that you have the right tool for the job and keep your tools in good condition – a dull blade is more dangerous than a sharp one! When working on DIY tasks around the home always keep a fully stocked first aid kit to hand and if possible, have somebody around to help you in case of an accident. Safety Tips For Plumbing Work Any plumbing work that you do must be able to pass inspection by a professional at all times. Therefore, if you are unsure about how to do something correctly you must call and ask the advice of a qualified plumber. Before starting your plumbing DIY work, be sure to turn off the water supply by using the appliance isolator valve or stopcock. Also, make sure to drain appliances of any excess water once the supply is turned off. If the job involves an element of electrical work you should keep a chemical fire extinguisher to hand (never use a water extinguisher) and be certain that the power is switched off if you need to make changes to an electrical system. Important Things to Remember Before You Start While you are eager to get going with installing your new dishwasher, there are a couple of important points to remember before you begin. A dishwasher is classed as a large appliance and on average it can weigh anywhere from 65-80 kilograms, making it tricky to lift and move by yourself. Also, because of their weight dishwashers can pose a damage risk to your flooring so it is recommended to lay down a mat or other protective apparatus to stop your kitchen flooring from being damaged. Before you set about removing an old dishwasher always be sure to check that you have removed all dishes, glasses, silverware, and anything else from the machine. If you are thinking about transporting an old dishwasher yourself you will need to enlist the help of family and friends, or a professional in moving the machine from the kitchen and into a vehicle. Due to the amount it weighs this is no easy feat and you should use the right equipment to avoid injury. If you are selling the dishwasher on or donating it to a good cause you should also think of ways to protect the appliance during transit – if it is left lose to roll around damage could be caused to both the machine and the vehicle transporting it. If you haven’t yet thought about what to do with your old machine, now is the time. You will need to think ahead about how you will dispose of your old dishwasher as they cannot simply be put out with the next rubbish collection. You will have to arrange to sell, recycle, or properly dispose of your old appliance when you are ready to get rid of it. Before you start disconnecting your old dishwasher or looking at installing your new one, you will need to acquaint yourself with the ins and outs of turning off your water supply, and maybe even your electricity supply if you need to move it to a new location. Take some time to find the stopcock to turn off your mains water supply just in case you need to use it.

Removing Your Old Dishwasher

Before you get started with plumbing in your new dishwasher, you will first need to disconnect and remove your old dishwasher. Enlisting the help of a second person for this task is advisable due to the weight and the bulkiness of a dishwasher. Before you begin disconnecting your old dishwasher, first get organised by having the right tools to hand. You’ll need;

  • Channel-lock pliers
  • Screwdrivers

Turning Off The Water And Electricity Supply Your first task is to turn off both the power and water supply to your old dishwasher. To shut off the water you will need to find the shutoff valve that controls the water supplying to your appliance. The shutoff valve is usually found underneath the kitchen sink and may be attached to a hot water pipe or a valve with two openings that control both the water to the sink taps and the dishwasher. In some cases, the original dishwasher may have been installed without a shutoff valve, so if this is the case you’ll need to turn off the main water valve so that you can disconnect the water lines from the dishwasher. If your dishwasher was installed without a shutoff valve, you will need to install one when you plumb in your new appliance. Current plumbing practices dictate that dishwashers require shutoff valves to comply with legislation. Once you have successfully shut off the water to the dishwasher, the next step is to cut off its electricity supply. You can do this by locating the power cord and unplugging it from the wall socket which again, is usually found under the kitchen sink. Disconnecting Pipes From the Plumbing System Finally, before you can move the dishwasher you will need to disconnect the pipes that link it to the plumbing system. There are two of these pipes, the first is the water supply tube and the second is the drain line. The water supply tube can be identified by looking for the tube that connects the dishwasher to the shutoff valve. This is usually a small copper tube or a plastic tube encased in a wire mesh. Once you have found the right tube, take a pair of channel-lock pliers, and disconnect the supply tube from the shutoff valve. If the dishwasher has been installed without a shutoff valve disconnecting the supply pipe is slightly more complicated. You will need to look at unhooking the compression fitting or the coupling nut that joins the dishwasher’s supply tube to the hot water pipe. To disconnect the drain line look for a rubber hose connected to the dishwasher and ending at a fitting that is mounted to the sink or countertop. Unfasten the drain hose from the fitting. Unfastening The Mounting Brackets And Lowering The Dishwasher To hold a dishwasher in place, it is usually fastened with metal mounting brackets that are screwed into the countertop above the dishwasher. Locate the brackets and remove the screws, leaving the dishwasher free. Finally, the dishwasher will need to be lowered by removing its legs. Locate the faceplate at the bottom of the dishwasher and find the legs. Then twisting the legs clockwise you will see that the dishwasher begins to lower. Lower it down as far as it goes to create enough space between the dishwasher and the countertop. Removing The Dishwasher Once the dishwasher is safely disconnected from the water supply and drain lines and you have unfasted the mounting brackets and lowered the legs, its time to move it! Carefully slide the dishwasher out of its cabinet by pulling it towards you. In some cases, you may need to lift it slightly first if it sitting directly on the subfloor. You also might need to ask another person to help feed the connecting hoses through the holes in the cabinet’s side as you move the dishwasher to avoid them becoming tangled and stuck. Disposing of Your Old Dishwasher There are several ways you can dispose of an old dishwasher to make way for your new model but always remember to follow the law and avoid fly-tipping. Firstly, if there is a lot of life left in the dishwasher you could consider selling it. Selling platforms such as eBay or Facebook market place will help you to easily find a buyer that will put your old machine to good use. Alternatively, you could also choose to donate your old appliance to a local charity. If your dishwasher is at the end of its life though, the most eco-friendly way to dispose of it would be to recycle it. Find a recycling hub to help you take care of the old dishwasher – some companies may even offer you cash for it. If there are no recycling hubs local to you, you could also arrange to drop the appliance off at your local tip, where it can be disposed of safely and correctly.

Finding The Right Space For Your Dishwasher

When looking for a home for your new dishwasher many people choose to install it into the same space as their original appliance. However, if you have never had a dishwasher in your kitchen before, or if you are thinking of rehoming it in a new location you may need to install it from scratch. There are a few things to keep in mind when choosing the space where your dishwasher will be installed. Firstly, it will need to be near to an electric plug socket for the power source, typically washing machines and dishwashers run off a 13 amp socket so a standard plug socket is fine. A common problem many people find in their kitchens is that the power sockets are often located above the countertops. If you find yourself in this situation you can run a spur from a socket to a switched fuse connection unit (which sits above your work surface). From this unit you can then run a cable to an unswitched socket below the work surface to power your appliance – just remember to use a connection with a power light so you know when the machine is switched on. Secondly, if the connecting pipe and the waste pipe are not already installed you will have to choose the right location for these. The manufacturer’s manual will tell you the minimum distance that you should keep between your appliance and the cold water tank, and you’ll also need to make sure the appliance is sitting on a firm, level floor. The dishwasher should come with a 1.5-meter hose that you can use to connect to the water supply and most dishwashers will only need a cold water supply. It is also recommended to have your dishwasher sitting against an exterior wall so that you don’t have the waste pipe running along an inside wall within your home. Always refer to the manufacturers’ instructions when choosing the right space to install your new dishwasher.

Installing Your New Dishwasher

Once you have removed your old dishwasher and settled on a sport for your upgraded model it is time to learn how to install it! Before getting started, check to make sure that you have removed all of the transit bolts that are put in place to stop the machine getting damaged in transport. Its also worth checking that the dishwasher is set at the right height, so before you begin plumbing it in, check that it fits into the space you have designated. If it is too tall or a bit wobbly, you will be able to adjust the feet until it sits at the right height.

What Tools Will You Need?

Before you get started make sure you have the right tools to hand. You will need:

How to Add a Water Supply Valve

  1. Before working on the water supply to the dishwasher, you will first need to turn off the main water supply. Once the main water supply is off, run a faucet that is close to the shutoff valve where you intend to install the appliance, or an outside faucet close to your water meter – this will take care of any excess water still sitting in the system.
  2. Look under your sink to find the hot water supply valve. Once you have located the valve, use a pair of pliers to loosen the compression nut that connects the supply pipe to the faucet. However, be aware that loose water within the system could drain out when the nut is loosened.
  3. Find and loosen the compression nut that holds the hot water supply valve to the copper pipe underneath the sink – you will need to do this using an adjustable wrench. Once loosened enough, try to pull the supply valve off the pipe including the compression nut and the copper ferrule that sits beneath the nut. If the supply valve, ferrule and compression nut slide off easily skip to step 6.
  4. If you are having difficulty sliding off the valve, ferrule and compression nut, you will need to hand-tighten the compression nut back onto the supply valve. Then attach a tubing cutter to the copper pipe directly behind the compression nut. Once you have done this begin tightening the handle clockwise on the cutter until the blade rests against the copper pipe.
  5. Start twisting the tubing cutter around the copper pipe, gradually tightening the handle. Continue rotating to cut through the pipe and release the supply valve. Once this is done, use the deburring blade attached to the pipe cutter to smooth the inside edges of the cut pipe.
  6. Clean the outside of the copper pipe to clear away any dirt – use the emery cloth to do this. Then use another clean cloth to wipe away any emery deposits.
  7. Ensuring that the threads are facing outwards, carefully slide the compression nut from a dual outlet/dual shut-off valve over the copper pipe. Then slip the brass ferrule that came with the new shut-off valve onto the pipe. Next, slip the new dual-outlet/ shut-off valve onto the pipe and slide the ferrule against the new valve. Finally, slide the compression nut over the ferrule and onto the threads of the new valve and tighten by hand.
  8. Using an adjustable wrench, hold the new supply valve to keep it stable. Then using another adjustable wrench, tighten the valve compression nut clockwise.
  9. Connect the hot water faucet supply line to one of the dual shut-off valves and leave the other free for the dishwasher supply line. Keep both of the valves handles turned clockwise until tight to make sure they stay in the off position.

Dishwasher Drain With Additional Garbage Disposal

  1. Start by unplugging the garbage disposal from the wall outlet found underneath the sink.
  2. Remove the discharge tube from the side of the garbage disposal by loosening the two screws holding it in place. Then carefully pull away the tube avoiding causing damage to the drain line.
  3. There are three circular tabs on the mounting collar holding the garbage disposal to the mounting bracket. Using a disposal wrench or a flat-blade screwdriver inserted into one of the tabs, turn the collar clockwise to release it from the sink.
  4. Once the garbage disposal is loose, lay it on the floor of your cabinet. Then thread a flat-blade screwdriver into the dishwasher drain connection (found above the discharge tube connection)
  5. Knock the drain plug from the disposal wall (you may need to lightly tap it with a hammer) Then reach inside the disposal unit and remove the plastic knock out.
  6. Replace the disposal in the mounting bracket underneath the sink and use the flat-blade screwdriver or wrench to secure the mounting collar back to the sink using counterclockwise motions.
  7. Reattach the discharge tube to the side of the garbage disposal unit and plug it back into the wall outlet.

Connecting The Dishwasher Drain Without Garbage Disposal

  1. Take a pair of tongue-and-groove pliers to loosen the slip but that holds the drain tailpiece to the drain basket underneath the sink.
  2. Twist the slip nut that holds the bottom of the drain tailpiece to the P-trap in a counterclockwise direction either by hand or with the pliers if necessary. Once loose enough, lift away the original drain tailpiece from the P-trap and remove the slip nuts from the tailpiece.
  3. Carefully measure the length of the original drain tailpiece and mark this out onto a new branch drain tailpiece. A branch drain tailpiece has two pipes, one of which is used to permanently connect the drain to the dishwasher line.
  4. Cut the bottom of the new tailpiece to match the measurements from the original piece and use an emery cloth to smooth the rough edges. Then slip the nuts onto the tailpiece.
  5. Insert the bottom of the new tailpiece into the P-trap and tighten the bottom slip-nut by hand or using the pliers. Be careful not to overtighten the nut and cause damage to the pipe.
  6. Then, insert the top of the new drain tailpiece into the drain basket. Slide the slip nut onto the drain basket threads and use the pliers or your hands to tighten. Again, be careful not to tighten the nut too much as this could cause damage to the drain line.

Adding Access Holes

You are almost ready to install your dishwasher, all that is left to do is to add the access holes for the power supply and pipelines.

  1. First using a drill and a 1 ½ inch hole saw, carefully drill three holes through the wall close to the floor of the kitchen base cabinet. You will need to drill one hole for the power supply, one for the supply line and one for the drain line. Try to keep the holes at least one inch apart and as close as you can to the back wall of the cabinet.
  2. Once the holes are drilled, feed the lines through the cabinet wall. Then attach the drain and water supply lines.
  3. Finally, plug the power cord into the electricity socket.

Testing Your Dishwasher

Before you push your dishwasher back into place, it’s always worth a quick test run to make sure there are no leaks. Significant leaks can be very damaging so double check that everything is working as it should be. Plug it in and run a quick rinse to double-check that all of the pipes and fittings are watertight, then if you are happy, you can put the machine into position beneath the worktop. Try not to push it too far against the wall as this could risk trapping the drainage hoses or damaging the water supply and cause harmful leaks or blockages.

Built-in Dishwashers

If your appliances are built into the kitchen cabinets then you have one additional step to take before you are finished – you will need to fix the appliance to the cabinets and attaching a decorative door so that it matches your kitchen. Fixing The Appliance in Place Usually, the appliance is supplied with fixing screws that go through the carcass from the inside to the worktop above and the sides of the cabinet. You may also need to adjust the height of the appliance to get it in the right position to fix it in place. If you are also installing a plinth to go across the base of your cabinets, you might need to cut a groove along the top edge so that the door opens properly. Adding The Decorative Door The appliance should come with the right fittings to attach the decorative door. Once it is attached and in line with the rest of the cabinet doors, you will need to adjust the tension springs to make sure that the door opens and closes smoothly. Remember, if you encounter any problems whilst trying to plumb in a dishwasher or if you are unsure of anything in this guide always seek professional advice from a qualified plumber. You should also refer back to the manufacturer’s handbook that comes with your appliance for guidance on installing your new dishwasher.