On this plan, ignore the location of the existing bathroom suite but mark the location of the waste outlets (especially the soil pipe), the water pipes (hot and cold), door, windows and radiator/towel rail.

Delivery time
Do not start removing the old suite until the new one arrives and has been checked to make sure it is the correct one, and that it has not been damaged.

Shower Or Not? Are you going to fit a shower or not? If so take care to get the correct type of shower that fits your plumbing system. Most DIY stores will have a guide to help you choose the correct type. If you can only get cold water to the shower then it must be an electric one (check you can get an electricity supply to the shower). If you have hot and cold supplies to the shower then you can have a mixer shower. If there is plenty of pressure in both the hot and cold water an ordinary mixer is needed. However, if the pressure in either hot or cold or both is low then a pumped shower may be necessary.

Is the shower going to be into the bath or a separate cubicle? If it is a separate cubicle, check that the waste pipes can be run to the outlet. Take care to waterproof the edges of the bath or shower tray properly. It is best to fit a waterproofing strip before the new tiles are fitted - this makes a more waterproof seal. Resin stone shower trays are more expensive but they do not twist under weight and so are easier to waterproof.

Building regulations insist that the waste trap for the shower tray can be accessed for cleaning. This will probably mean fitting a removable hatch to the front of the tray.

Waste System
The waste system is the least flexible aspect of the bathroom the waste pipes must run downhill from the appliance to the soil pipe or outlet. Bear this in mind when planning the new location of the appliances. The waste system includes the soil pipe - the large (100mm) diameter pipe that the WC flushes into. In newer houses this will be plastic. In houses built before the 960s this may be cast iron. Some older houses (1930s) may have a system where the water from the sink and bath (this is called grey water) go into a hopper set on top of a down pipe on the outside wall.

If this is the case, run the new waste pipe to this hopper. Bath and shower wastes are very close to the floor - to get a good slope (fall) the entry into the soil-pipe must go quite low - in many cases this will be under the floor. Waste water does not run uphill so plan carefully. The only way to overcome this is to fit some form of sewage pump like a Saniflo. However, this may be an expensive way to do the job and a Saniflo does make a noise when pumping.

Waste Pipes
The waste pipe to the basin and shower tray will probably be 1.5" (32mm) and that to the bath 1.5" (38mm). Building regulations will specify the sizes and fall of the waste pipes so, if in doubt, contact your local building control office - in most cases this will not be necessary. Remember to clip these pipes once they have been run- any sagging will allow gunge to build up in them and its weight may pull the fittings apart or cause the pipe to sag even more.

There are three ways that waste pipes can be joined:

Universal or compression fittings These will fit all the slight variations that occur in the sizes of pipes made by different manufacturers. The best way to fit these is to remove the large nut (screw fitting) and rubber ring (washer) from one end of the fitting and feed these onto the waste pipe, taking care the rubber washer is slid onto the pipe the correct way around. Push the end of the pipe into the fitting and screw the nut up a little tighter than hand tight. The reason for removing the nut and the washer is that it is easy not to get the washer onto the pipe but to crunch it up at the base of the fitting. If this happens the joint will leak.

Push-fit fittings are exactly what the sound like, you push the pipe into the fitting. Because the sizes vary a little from manufacturer to manufacturer, you need to use the same make of fitting and pipe.

Stick-fit. These are cheaper to buy and take up less space but once stuck they cannot be taken apart. Plastic waste pipe can be cut sing a hacksaw or a special cutting tool. Use a file or coarse abrasive paper to make sure that all the burs on the inside and outside of the pipe have been removed.

Fit a rodding-eye in the system so that any blockages can be cleared. A good place to locate this is on a bend, a 'T' can be fitted instead of a bend (elbow) and the rodding-eye can be fitted in the spare leg of the 'T'.