Plumbing-In a Washing Machine or Dishwasher

With today’s easily obtainable plumbing supplies and fittings, plumbing a new washing machine or dishwasher is a relatively straightforward operation. Simple installations are well within the capabilities of any competent DIY enthusiast. Installations that are more complex may need the assistance of a general handyman or plumber to ensure that pipe fittings are correctly incorporated to allow the appliance to function reliably.

Perhaps the simplest installation is the replacement of an existing appliance with a new one. So long as the electricity plug has been removed from its socket, the water in-line supply valve turned off, the hose(s) unscrewed and the waste pipe disconnected; the old appliance can be eased from its existing position and disposed of.

In the case of a new washing machine, first, remove all packaging and either keep it in case it may be required again, or dispose of it. The main thing is to get it out of the way. Then, and with reference to the manufacturer’s installation instructions, the drum transit restraining bolts must be removed completely from the machine. These bolts prevent the drum from moving on its axle during transport. Failure to remove the bolts before operating the machine will seriously damage it. Keep these bolts safe in case it becomes necessary to transport the machine in the future.

To prevent unbalanced drum operation, the machine must be level. This can be achieved using a spirit level whilst adjusting the machine feet. The machine must also be stable and not able to rock when operating. The feet should also be adjusted to ensure that the machine will fit comfortably below any work surfaces.

Modern washing machines now have a single water connection hose. This has a fitting coloured blue and should be screwed onto the cold water supply fitting. This fitting should only be tightened by hand. The drainage and electrical fittings should all fit into the old connections with no need for modification. The new washing machine can then be slid into the existing space, taking care not to kink any of the pipes whilst doing so. The water supply can then be turned back on at the inline valve. Prior to switching on the electrical supply, it is a good idea to ensure that the operating switch on the machine is turned off otherwise the machine door will automatically lock when the power is supplied.

The manufacturer’s instructions will probably recommend running the machine empty on a hot wash prior to attempting to wash any fabrics. During the first operation, it is a wise precaution to monitor the machine and connections for any problems that might arise.

Installing a replacement dishwasher follows the same procedure; however, there are no transit bolts to remove. The machine must be level to ensure effective dish washing operation. Fittings are generally identical the previous installation.

To provide installation points for a new washing machine or dishwasher, slightly more complex plumbing procedures are required; however, it is possible to obtain all the necessary parts in a kit from major DIY outlets.

The first thing to consider is where to position the appliance. Not all appliances have to be located in the kitchen. Some homeowners prefer to locate appliances, particularly washing machines, in garages or conservatories. However, consideration must be given to frost protection.

Dishwashers tend to be located in the kitchen due to the frequency of operation and for convenience.

What both appliances require are a power source and water and waste connections. For that reason, both appliances tend to be located in the kitchen close to the sink where access to a cold water supply and drainage is readily available. In all probability, an electric socket will also be on hand to plug the appliance into.

To make a water connection to a cold pipe, first, isolate the pipe area or turn off the rising main. Drain the system as much as possible and then cut out a section of the supply pipe to accommodate a T fitting. All fittings should be either soldered or compression joints, depending on preference. An adequate length of pipe should be fitted into the T with an isolation valve to cut off the water supply in the event of a hose failure. A suitable connector should then be fixed to the end of the pipe to accommodate the machine hose. Incorporating a check valve should also be considered.

It is possible to obtain self-boring fittings that simply screw into existing pipework. These should be securely attached to a wall and in the off position prior to operating the self-tapping valve. It is also advisable to check with the water supplier that these fittings are permitted.

To fit a waste drainage connection firstly check the appliance manufacturer’s recommendations to ensure that a suitable outlet will be provided. The most common outlet consists of a vertical pipe with a minimum 40 mm diameter. This vertical pipe must have its top opening high enough to prevent any back-flow of water into the machine. This can be plumbed into the sink waste pipe with a suitable connection. The top of the pipe accommodates the machine waste pipe that simply hooks onto it. It is possible for two machine drainage pipes to be hooked onto this down pipe but it might not be advisable to have both machines draining at the same time.

Alternatively, a dedicated drainage fitting can be installed directly into the sink drainage system just above the trap. This fitting usually has two branches to accommodate two appliance drain hoses. Prior to fitting the drain hoses, blocking caps, either fitted internally or externally on each branch must be removed. In some instances, they may need to be sawn off.

To fit either appliance in a garage or alternative position, it will be necessary to provide independent water and drainage supply pipes. Although this can be straightforward if services are within easy access, providing these points may require professional intervention, particularly where new electrical installations will be required.

In general, installing a washing machine or dishwasher can be carried out without the need to employ a professional plumbing engineer.