Alterations or improvements to kitchens invariably start at the sink. Fashions and styles have played their part here over the years. Fine 'Belfasts' - deep, white glazed stoneware sinks were once seen as old-fashioned and were replaced in many homes by shiny new stainless steel all-in-one sinks and drainers. Now many have decided these are outdated: stainless and enamelled steel and plastic sinks in a huge range of styles and colours make for more contemporary kitchens, while other people are busy reclaiming and re-installing Belfasts to complete a country-cottage or period-style kitchen.

One-piece sink tops are made to modular sizes that fit standard kitchen base units. Furthermore, they are available with single or double bowls and left or right hand drainers.

To complement the sink, a range of styles of taps is also available. These are much like the taps used in the bathroom except that they have extended pillars to enable you to fill a bucket from them. There is also one other important distinction for a kitchen mixer tap: because mains water for drinking must not be mixed with water from storage cylinders providing hot water within a fitting, a sink mixer has two separate water-ways to isolate one supply from the other. If you are buying a mixer tap for the kitchen sink, make sure it is the correct one, and, if you are installing a double bowl sink, get a mixer with a swivelling spout.

Fitting a like-for-like replacement sink into an existing kitchen unit is pretty straightforward, but if you decide on a different size, combination or layout of sink, then you may have to replace the base unit as well - or at least replace the worktop surround. To do this, you could either purchase ready-made surrounds or make your own - which requires only basic carpentry skills.

Follow the later section on boxing in a washbasin but adjust the design depending on what you want to use the storage space in your kitchen for.

Fitting a New Sink

1 - Fit taps, overflow and waste

If you are making a straight like-for-like sink replacement, fit the taps, waste and overflow to the sink before you position it. Clamp the new sink in position with the fittings provided and then connect to the rising main cold supply, the nearest branch pipe of the same size from the hot supply and the pipes to the taps.

2 - Making a new work top

Where a replacement sink will not fit into an existing kitchen unit worktop, a new one can be made easily. Laminated birch blockboard is available at DIY stores and timber merchants in a variety of decorative colours and patterns. Turn the new sink onto the laminate board and draw around the perimeter.

3 - Measure and mark

If you cut the line you've marked, the sink would fall through it. The edge or lip of the sink should rest on the edge of the aperture. Measure and mark a line inside the first line to accommodate the lip of the sink. Mark also the position of the taps.

4 - Start by drilling holes

To cut the inner line, start by drilling a hole in each corner. This will allow you to insert the blade of the saw to start cutting and will make it easier to saw around the corners.

5 - Cut out the aperture

Using a power saw, cut slowly and carefully along the inner line to make the aperture for the sink. Cut out the holes for the taps.

6 - Fit the new sink

Fit the taps, overflow and waste to the new sink before you put it in position on the new worktop. Clamp the sink to the worktop using the fittings provided.

7 - Connect the taps

Run a 15mm ('Ain) cold supply from the rising main and a branch pipe of the same size from the nearest hot water pipe. Connect the pipes to the taps with standard or flexible pipe and tap connectors.

8 - Fit the trap

It may be possible to fit the trap of the old sink to the new waste outlet. If not, fit a bottle trap with an adjustable inlet which gives the little bit of extra tolerance needed to connect with the old wastepipe. Run a 43mm (1'/in) wastepipe through the wall behind the sink unit to the yard gully.

• The sink waste should be taken to an outside gully rather than connected with the main soil and waste stack. Current regulations require the wastepipe to pass through the grid covering the gully but stop before the pipe reaches the water in the gully trap to avoid siphoning up soiled water.
• When using a power saw, wear goggles to protect your eyes and a dust mask to stop you breathing in fine particles. If you are operating power tools for a long period, it is advisable to wear a pair of ear protectors as well.