How to Change Your Kitchen Plumbing

If you decide to update your kitchen, you will find that renewing, re-routing or extending plumbing services is usually needed. While basically hot and cold water is needed at the kitchen sink, you may want to provide services for permanently plumbed-in appliances such as waste eliminators, dish-washers and washing machines.

Kitchen re-plumbing, more often than not, is needed as a result of updating services and fitting new sink units. This may mean re-routing of existing plumbing and the replacement of old lead-work or iron pipe.

For example, an existing set of taps may be of the ‘bib’ or wall-mounted type, which need routing through the base of a stainless-steel sink unit. These are normally fitted with fixing holes to admit pillar taps.


Modern sinks are usually made of stainless steel, vitreous enamel, plastic or plasticized steel. These may consist of single- or double-drainer units. Single-drainer tops can be either left or right-handed. Tops can also have single or double bowls.

The waste outlet on a modern sink is usually of 35mm diameter. If, however, a kitchen-waste eliminator is to be fitted beneath, the hole must be capable of enlargement to a diameter of 90mm. This also almost certainly dictates the use of a stainless-steel sink, as other types are not normally capable of having the outlet enlarged.

Modern sinks are supported on a base cabinet by brackets and fixing rails. Fixing may vary slightly with differing makes.


Taps may be single or mixer. Holes are usually cut in the top of the unit, at the rear, to admit the taps. Taps are bedded in the sink unit in either a thin rim of non-hardening mastic or the joint is sealed with polypropylene washers. A plastic ‘top hat’ connector then screws on to the tails of the taps from beneath; lock nuts are tightened over these.

Next, ‘tap’ or swivel connectors, either straight or angled to meet the pipework arrangement, are screwed on to the tails and tightened. These can be either capillary or compression ended, and may contain a. fibre washer to provide a seal, or PTFE sealing tape is wound around the threads to effect a seal.

Mixers are fixed in basically the same way as individual taps, with hot and cold connections made to the appropriate stems, since the mixing function is performed within the body of the tap.


In the kitchen, service connection normally comes direct from the rising main, using a ‘tee-piece’ branch connection; the service is carried on to supply the cold-storage cistern. Cold-water pipe-work is usually of 15mm diameter but can be 10mm if the service is in plastic tube.

Once the sink top is lined up and taps and terminals are fitted, check that the outlets meet the supply pipes. It may be necessary to angle pipework to facilitate connections. It is best to use a pipe spring or bender rather than small fittings, as this will reduce water turbulence, although there may be cases where the very-tight angle afforded by a fitting is necessary. Pipes should be clipped to the walls at intervals to cut stress and vibration.

Outlets and traps

The waste outlet is next fitted. The waste is either bedded in non-hardening mastic or set into a rubber washer. The waste grill is fixed by a centre bolt. A washer fits over the waste connector which, in turn, is screwed to the threaded sink outlet.

Before screwing the trap on to the outlet stem, check that it is in line with the waste outlet. The kitchen trap should be 75mm deep. You can use either a tubular or bottle trap. These can be made of lead, copper or plastic. The plastic type, screwed together with a rubber ‘o’-ring seal, is quick and reliable to fit and needs no special skills.


Some overflows have a flexible tube connected to the overflow grill and then to a screwed boss on the waste trap. The trap should be readily accessible, in case of possible blockage. The waste-outlet pipe can be in plastic tube, fed into a trapped yard gulley. A slight fall should be maintained on pipework for waste services.

Plastic pipework cannot readily be bent, so fixed or variable elbow bends are used to provide an angle or change of direction. Most plastic pipework and bends are connected by the solvent-weld method. Elastic tube is easily cut with a fine-toothed hacksaw blade.

10. November 2011 by admin
Categories: Featured, Handyman Tips | Tags: , , , , , , , , , | Comments Off on How to Change Your Kitchen Plumbing


Get every new post delivered to your Inbox

Join other followers: