Plumbing work: cost of plumbing per point 2026 and process

If you live in an older flat or house, your water probably still comes through galvanised steel pipes. After a few decades they rust on the inside and fill up with limescale. From the outside the pipe looks the same, but the space inside keeps shrinking. You notice it when someone runs a bath and you turn on the kitchen tap: the flow drops right away. After a holiday, brownish water comes out of the tap for a while, and small drips appear at the threaded joints. That is why plumbers usually replace old steel pipework in full when a bathroom or kitchen is renovated, rather than patching it bit by bit.

For new pipework you will mostly come across three materials:

• Polypropylene (PPR): the plumber fuses pipes and fittings together with a heating tool. The joints are strong and the material is inexpensive. PPR pipe grows noticeably longer when hot water runs through it, so hot lines need room to expand and the right fixings.
• Multilayer pipe: a plastic pipe with a thin aluminium layer in the middle. You can bend it, it expands much less when warm, and the joints are pressed with a special tool. It works well in floors and in walls.
• Copper: tough and very long-lasting, but it costs more and takes more skill to join. Plumbers use it less than they used to, often where pipes stay visible.

Waste pipes indoors are usually polypropylene, which copes with hot water without trouble. Underground and outside, you need thick-walled drainage pipe that the manufacturer has designed for burial.

Right after the water meter or main stopcock there should be a filter. It catches sand and grit from the public mains before they reach your taps and appliances. If the mains pressure is high, a pressure-reducing valve belongs here too. Why does this matter? Constant high pressure strains taps, toilet cisterns, the water heater and the washing machine, and they wear out sooner. Pressure that is too low shows up as a feeble shower, especially upstairs in a house.

In many regions the water is hard. Limescale settles in the water heater, in taps, aerators and shower heads, and a scaled-up heater warms water less efficiently. You can fight it with a water softener or a polyphosphate dosing unit fitted after the filter. Which one suits you depends on how hard your water is. Your water supplier can tell you, and a simple test kit from a DIY shop gives a good idea too.

Newer installations often use a manifold instead of one main pipe with branches. A separate pipe runs from the manifold to each basin, shower and toilet. When several taps run at once, the pressure stays steadier, and you can shut off each circuit on its own, for example when you change a tap.

The exact position of the water outlets depends on the sanitaryware you choose. So pick your basin, taps and toilet before the plumber starts cutting channels in the wall. As a rough guide, outlets for a washbasin or kitchen sink sit about half a metre above the floor, outlets for a bath mixer a few dozen centimetres above the rim of the bath, and outlets for a shower mixer at around one metre. The manufacturer's data sheet always has the final word. This matters most with concealed mixers and WC frames, because they need a precise depth as well as height.

Looking at the wall from the front, hot water normally goes on the left and cold on the right. A pair of outlets for a wall-mounted mixer must match the standard spacing mixers are made for, and both outlets must sit exactly level. In practice it often happens that the outlets stick out too far from the tiles, or sit too deep. The mixer then does not fit flush against the wall, and extension pieces rarely look neat.

In the kitchen, place the outlets so you can reach them under the sink and they do not get in the way of the cabinet drawers. For a washing machine and dishwasher, plan an appliance valve with a non-return valve and a waste connection with a trap, so drain smells stay out of the room.

A waste pipe has to slope steadily down towards the soil stack. It must never rise again along the way, and it must not sag, because water sits in a dip and dirt builds up there. The toilet waste is wider than the others and the plumber plans its route first, since it is the hardest one to move later. The other wastes join it, or join the stack directly, with angled branches pointing in the direction the water flows.

Drainage also needs air. When a lot of water rushes down the stack, it creates suction that can pull the water out of the traps. A trap without water leaves an open path from the sewer into your home, and the bathroom starts to smell. That is why stacks are vented above the roof, and why longer waste runs get an air admittance valve.

In blocks of flats, think about noise as well. A plastic stack can carry the sound of running water through the whole building. Acoustically insulated pipe, insulation wrapped around the pipes and resilient brackets that do not fix the pipe rigidly to the wall all make a real difference.

In a block of flats, the water and drainage risers are usually part of the common parts of the building. You do not replace them on your own: the building management or owners' association organises it, typically for a whole stairwell at once. Before you start redoing your bathroom, ask whether riser replacement is planned. If it is, time your renovation around it and adapt the plans.

Some older blocks still have soil stacks made of asbestos cement. An ordinary plumber must not cut or remove such pipe during a flat renovation. Only a contractor licensed for asbestos work may do this.

The water meters and the isolation valves on the supply into each flat are often sealed. If you want to move them, talk to the building management first. Isolation valves should sit behind an access panel where you can reach them, and before anyone works on the pipes, check that they really shut off completely.

For a larger rebuild of a bathroom or kitchen, especially if walls or the soil stack connection change, ask your local building authority whether you need a permit or a notification. Rules differ from country to country, so do not assume a simple notice will be enough.

In flats, water is most often heated by an electric storage water heater, a tank that keeps hot water ready. You choose its size according to how many people live with you and whether you take baths or mostly shower. It needs a safety valve on the cold water inlet. If the valve drips while the heater warms up, nothing is wrong: water expands as it heats and the extra has to go somewhere. That is why the valve connects to a waste pipe and must never be blocked off.

Inside the tank sits a magnesium anode that protects the steel from rust. It slowly dissolves, so it needs replacing after a few years. With hard water, it is a good moment to clear the limescale from the bottom of the tank as well. If you change the anode regularly, the heater lasts years longer.

If you have a gas boiler or a heat pump, your hot water is usually heated indirectly, in a cylinder connected to the heating system. Only a qualified, registered gas engineer may work on a gas boiler or gas pipes. If you ever smell gas, do not touch light switches or use any open flame, open the windows, get to a safe place and call 112 or your local emergency number.

An instantaneous water heater warms water only while you run it. It stores nothing, but it needs a high power supply, so check your electrical connection first. For long hot water runs, consider a circulation loop, so hot water reaches the tap straight away and you do not waste water waiting. It is also wise to heat stored water regularly to a sufficiently high temperature, because bacteria such as Legionella can multiply in lukewarm water that stands for a long time. Your heater's manual usually states the recommended setting.

Plan the outside tap and garden pipes so you can drain them before winter. A separate stopcock inside the house and a drain valve at the lowest point of the pipe make this easy. You can also fit a frost-proof outside tap. It closes the water deep inside the wall, in the warm part of the masonry, so no water stays in the outdoor section. In many places the water regulations also require a check valve on outside taps, so a garden hose cannot draw dirty water back into the mains.

Insulate any pipe that runs through unheated spaces, such as a cellar, a garage or a crawl space under a suspended floor. An outdoor water meter chamber has to be deep enough and properly covered so the meter does not freeze in winter.

A leak is one of the most unpleasant and expensive kinds of damage. Water ruins floors and walls, and in a flat it often reaches the neighbours below. Where do leaks usually start? At the flexible connectors under taps, at washing machine and dishwasher connections, and at pipes that burst in frost. So replace flexible connectors as a precaution after some years, before they start leaking. For the washing machine and dishwasher, hoses with burst protection are worth having.

Another option is a leak protection system. Sensors on the floor next to the washing machine, under the sink and in the bathroom detect water and close the main valve automatically. And when you go away for a while, shut off the main water supply to your home. It takes a moment and can save a lot of trouble. It is also worth checking what your home insurance expects from you here.

If your washbasin drains slowly or a tap gives only a weak flow, you can often sort it out without a plumber. All you need is a bucket, a cloth and a little patience.

1. Place a bucket and a cloth under the washbasin trap.
2. Loosen the bottom part of the trap or the nuts on the bend by hand and remove the trap carefully.
3. Clear out dirt, hair and deposits, rinse the trap with warm water and check the seals.
4. If possible, push a drain spring into the outlet in the wall and break up any blockage further along the pipe.
5. Put the trap back together, hand-tighten the nuts and run the water. Check that the joints do not drip.
6. Unscrew the aerator at the end of the tap spout, using pliers over a cloth if needed so you do not scratch it.
7. Soak the aerator in vinegar or descaler for a few hours, rinse the little screens and screw the aerator back on.
8. Use harsh chemical drain cleaners only as an exception. They damage seals, and if the drain is fully blocked they just sit in the pipe.

• You have received a record of the pressure test carried out before the pipes were covered
• You have photos of the pipes in walls and floors, with distances measured from corners and from the floor
• The main stopcock and the isolation valves for each circuit are accessible and labelled
• Every tap gives a good flow, even when water runs at several points at once
• Wastes drain quickly without gurgling, and there is no smell from the traps
• Under the washbasin, the sink and next to the washing machine everything stays dry after several minutes of running water
• The water heater safety valve is connected to a waste pipe