DIY GUIDE · PLUMBING & HEATING · CHECKED OCTOBER 2026
How to do the small plumbing jobs yourself
An afternoon for all three. £15–£36 for a bleed key, a plunger and a pack of washers.
Bleed and top up, a tap or a waste, a blockage you can reach. Three jobs, done properly — and where each one stops.
- Every step, start to finish
- Checked October 2026 — sources at the end
- Honest about when to call a pro
FIRST, THE HONEST ANSWER
Do it yourself, or get a plumber?
Do it yourself if…
- Radiators are cold at the top, or the boiler's pressure needle has dropped below its green band
- A tap drips, a waste is slow, or a trap under a basin or sink is dripping
- One fitting is blocked and the others in the house drain normally
- The fitting has an isolating valve or the stopcock turns off fully
Get a pro if…
- Anything involves the gas side of the boiler, its burner, flue or the inside of its case
- The boiler keeps losing pressure, the hot water comes from an unvented cylinder that needs attention, or the mains supply is involved
- Pipework has to be moved, added or cut into
- A leak or blockage is out of sight, inside a wall, under a floor or beyond your boundary
Safety first
- Isolate before you dismantle. A tap or joint undone on a live pipe sprays at mains pressure.
- Bleed radiators only when the heating is off and the system is cold. System water is hot, dirty and under pressure.
- Nothing here touches the gas side of a boiler. That work is restricted to Gas Safe registered engineers, and there is no small exception. If you smell gas, leave the house and ring 0800 111 999 from outside.
- Never mix drain chemicals, and never plunge or open a trap after using one. HSE's guidance on hazardous substances applies at home as much as at work.
- If water reaches lights or sockets, switch off at the consumer unit first, without standing in water. HSE's electrical guidance is always to isolate before going near.
Stop here: Stop here: the mains, the gas side and pressurised systems
The householder's part is bleeding, topping up through the existing filling link, a washer or cartridge, a trap, and a blockage within reach. Any work on a gas appliance or fitting, including the gas side of a boiler and its gas controls, is restricted to Gas Safe registered engineers by the 1998 Gas Safety (Installation and Use) Regulations in England, Wales and Scotland and by the 2004 Regulations in Northern Ireland. An unvented hot water cylinder is controlled under requirement G3, with England's Approved Document G as guidance and the other nations' building regulations to the same effect. New or moved water fittings must meet the 1999 Water Fittings Regulations in England and Wales, the Scottish Water byelaws in Scotland, or Northern Ireland's 2009 Water Fittings Regulations. How to hire a plumber →
| MATERIAL | COVERAGE | FOR THIS JOB |
|---|---|---|
| Tap washers | Matched to the tap size | A mixed pack |
| Ceramic cartridge | Matched to the tap's make or spline count | One or a pair, only if cleaning fails |
| Trap washers | Matched to the trap size | A spare or two |
| Silicone grease | For tap O-rings | A small tub |
What the three jobs cost against an hourly rate
Saving = the plumber's hourly rate × hours saved − the tools. One bleed, one tap and one blockage is about three hours of a plumber's time; at a typical hourly rate that is several times the cost of a key, a plunger and a pack of washers.
The tools last. The second time you need them, the saving is the whole hourly rate.
A pressure gauge on the boiler means a sealed system, which loses pressure when you bleed and has a filling link to top it up. No gauge and a small tank in the loft means an open-vented system, which tops itself up. A boiler maker's filling guide we checked sets the sealed system's working band at 1 to 1.5 bar; your boiler's own instructions are the authority.
Turn the handle. Several full turns from off to on means a rubber washer inside; a quarter or half turn means a ceramic cartridge. A single-lever mixer has one cartridge. The tap maker's maintenance page shows how to take the handle off and lift the cartridge out to clean or replace it.
Under a basin there is usually a bottle trap whose bottom unscrews for cleaning. Under a sink there may be a bottle or tubular trap with an appliance spigot. Plastic trap nuts are hand tight, and the washers inside do the sealing. A bottle trap maker's instructions we checked set the outlet with a small fall back to the wall so water runs away.
Most taps, toilets and appliances have an isolating valve with a screwdriver slot; a quarter turn across the pipe shuts it. The stopcock shuts the whole house. Find both and check they turn before you start any of these jobs.
A radiator bleed key, a flat screwdriver, two adjustable spanners, a flange plunger and a plastic drain hook do almost every small job in this guide. A spares box with tap washers, olives and trap washers makes the next one a ten-minute fix.
If you are doing more than one job, do the heating first while the house is cold in the morning, then the tap with the water isolated, then the blockage last, because it is the dirtiest and you want the cleaning kit out once. Keep the stopcock key, a torch and towels on the landing for the whole day so nothing has to be fetched in a hurry.
THE PART THAT DECIDES THE FINISH
Before you start — which small job you have
Four starting points, each with its prep. Find yours and do the prep before you pick up a tool.
Cold radiators or low boiler pressure
Air in the radiators, or water lost from a sealed system.
- Turn the heating off and let the system go cold
- Read and photograph the cold pressure on the gauge
- Find the filling link and the page for it in the boiler's instructions
- Lay towels under the bleed valve end of each radiator
A dripping tap
A washer, a cartridge or a gland.
- Close the tap's isolating valve, or the stopcock
- Open the tap to drain it and plug the sink
- Work out whether it is a washer tap or a ceramic tap
- Lay a towel in the sink to protect it from dropped tools
A slow or dripping waste
Hair, soap or a tired washer in the trap or waste.
- Pull hair out of the plughole with a plastic hook
- Put a bowl under the trap and wear gloves
- Check the plastic nuts are hand tight
- If it drips, note which joint before you dismantle
A blockage you can reach
One fitting slow, the others fine.
- Check other fittings drain normally — if several are slow, it is the drain, not the fitting
- Have a flange plunger, a bucket and gloves ready
- Block the overflow with a wet cloth before plunging a basin or bath
- Do not use chemicals first; they make every later step dangerous
THE JOB
How to do the three jobs
Set up: isolate, cool, find your case
20 minRead the cards above and do the prep for your job. For the heating, turn it off and let it cool. For a tap, close its isolating valve and open the tap. For a waste or a blockage, lay towels, put a bowl under the trap and put on gloves. Find the stopcock in every case, so you know where it is if something goes wrong.
- Photograph anything before you take it apart
- Plug the sink or bath so small parts cannot go down it
- Turn off the boiler or immersion heater before working on a hot tap
Mistake to avoid: Starting a tap with the isolating valve half closed. The headgear comes out and mains pressure follows it.
Bleed the radiators
45 minThis is the first card's job. Start downstairs at the radiator furthest from the boiler. Hold a cloth round the bleed key, a bowl under the valve, and turn the key anticlockwise a quarter turn. Air hisses out. When water runs steadily, close the valve snugly. Work through the house, downstairs then upstairs, checking the boiler's gauge every few radiators.
- A quarter turn only; more and the plug can come out
- Snug, not tight; over-tightening damages the seat
- Note which radiators had most air
Mistake to avoid: Bleeding the whole house without checking the gauge. The pressure falls below the band and the boiler locks out.
Top up the pressure
10 minWith every bleed valve closed and the system cold, open the filling link exactly as your boiler's instructions show. Watch the gauge rise and close the link as soon as the needle sits in the green band. On an external loop, close both valves and refit the caps. Run the heating, let it cool, and check the cold reading again.
- It fills quickly; be ready to close
- If you overshoot, let a little water out of a bleed valve
- Write the cold reading and the date inside the boiler cupboard
Mistake to avoid: Leaving the filling link open. The system stays tied to the mains and the pressure climbs as it warms.
Fix a dripping tap
30 minWith the water isolated, prise off the handle cap, undo the screw beneath and pull the handle off. Hold the tap body still and undo the headgear or cartridge nut. On a washer tap, replace the washer on the jumper. On a ceramic tap, rinse the cartridge under cold water as the tap maker's page shows, and replace it with a matching one if the drip persists. Reassemble and turn the water back on slowly.
- Hold the tap body so it does not turn on the basin
- Grease new O-rings with silicone grease
- Ceramic cartridges need firm tightening, not force
Mistake to avoid: Fitting a cartridge that is nearly the right size. The tap no longer turns fully off.
Clean or change a trap
20 minUnscrew the bottom of the bottle trap, or the trap's nuts, by hand into a bowl. Clean it, check the washers, and refit hand tight. If the trap is cracked, fit a new one of the same size, lining its outlet up with the pipe with a slight fall back to the wall. Fill the basin and empty it to test under load.
- No tape on plastic threads; the washers seal
- Hand tight is enough; grips crack plastic nuts
- A trap pulled up under strain will always drip
Mistake to avoid: Using PTFE tape on a dripping trap thread. The washer cannot seat and the drip gets worse.
Clear the blockage
20 minFor a basin or bath, pull out hair with a hook, then block the overflow with a wet cloth and plunge hard ten or twelve times. For a sink, plunge with the second plughole blocked, then clean the trap. For a toilet, bail to half full and plunge with a flange plunger sealed in the outlet. Test with water poured from a bucket before flushing.
- Overflow sealed, or the plunger pushes nothing
- Push the first toilet stroke gently, then firmly
- If several fittings back up at once, the blockage is outside
Mistake to avoid: Flushing a blocked toilet to see if it has cleared. A full cistern goes over the rim.
Test everything
20 minTurn the water back on slowly. Hold a dry tissue under every joint you touched. Run each tap and fitting at full flow. For the heating, check every radiator is hot top to bottom and the cold pressure is still in the band the next morning.
- Kitchen roll under each repair overnight
- A weep usually needs a quarter turn more, not a full turn
- Air spits from taps after isolation; run them until steady
Mistake to avoid: Declaring it done after one look. Slow weeps show over hours.
Know when it has stopped being small
5 minA boiler that loses pressure again within days, a tap that drips again after a new washer, a blockage that returns, or a damp patch you cannot trace are the signs that the job has outgrown this guide. Write down what you did and what you saw, and call a plumber with that information.
- Note readings and dates; they save the plumber's time and your money
- Ask for the hourly rate and any call-out charge first
- Keep the stopcock and valves working by turning them twice a year
Mistake to avoid: Repeating the same small fix every week. A fault that keeps coming back is a bigger problem underneath.
The mistakes that show
- Bleeding radiators while the system is hot
- Leaving the filling link open after topping up
- Working on a tap with the water half on
- Taping plastic trap threads instead of trusting the washers
- Flushing a blocked toilet again
- Forcing a stiff stopcock or valve with grips instead of steady hand pressure
Stop here and get a plumber
- The boiler keeps losing pressure, shows a fault code, or anything involves its gas side
- Pipework has to be moved, extended or cut into
- The leak or blockage is out of sight, or several fittings are affected
- The hot water comes from an unvented cylinder that needs attention
- A damp patch, a musty smell or a rising water bill with no visible cause
| WHAT YOU SEE | WHY, AND THE FIX |
|---|---|
| Radiator still cold at the top after bleeding | More air has arrived. Run the heating, let it cool, and bleed it again. If it fills with air every week, call an engineer. |
| Boiler pressure keeps dropping | Water is leaving the system. Check radiator valves and the small safety-valve pipe outside for drips; if nothing shows, call a heating engineer. |
| Tap still drips after a new washer | The seat in the tap body is worn. It needs reseating or the tap needs replacing. |
| Ceramic tap drips after cleaning | The discs are chipped. Fit a matching new cartridge from the tap's maker. |
| Trap drips after refitting | A washer is folded or the trap is strained. Reseat the washer and line the trap up so it is not pulled into place. |
| Basin still slow after plunging | The blockage is past the trap. Clean the trap and feed a drain spring into the pipe beyond it. |
| Toilet still blocked after plunging | The blockage may be in the drain outside. Lift the nearest inspection chamber cover; full means it is further down. |
| Boiler shows a fault code after topping up | Reset it as its instructions show. If the code returns, it is not a pressure problem and needs an engineer. |
| Air spitting from every tap after the work | Air entered when the pipes drained. Open each tap in turn, starting downstairs, and let it run until the flow is smooth; it clears within a minute or two. |
| Waste gurgles after cleaning the trap | The trap has not refilled, or a long pipe run is siphoning it. Run the basin full and drain it; if the gurgle persists, a resealing trap is the fix. |
WHAT YOU SAVE
What it costs to do it yourself
| Radiator bleed key | £2–£6 |
|---|---|
| Flange plunger | £4–£10 |
| Tap washers, pack | £1–£3 |
| Adjustable spanner, if you have none | £8–£17 |
| Total | £15–£36 |
| DIY total | £15–£36 |
Guide prices compiled by the Locufy team from published Irish and UK provider price lists and 2026/27 cost guides. Updated 2026.
A plumber's guide price is an hourly rate. The tools for these three jobs cost less than one hour, and they are still in the drawer next time.
RATHER NOT?
Plumbers near you, with prices shown
The ones who cover your area, nearest first, with one score from every review. No account needed to look.
Or post the job free and let them come to you.
Tap washers, olives, trap washers, silicone grease and the bleed key, in a labelled box with the tap and boiler models on the lid.
A cold reading once a month in the heating season shows a slow leak before it becomes a cold house.
Rubber washers and plastic parts go in general waste. Brass tap parts and old fittings go to the metals container at your council's household waste recycling centre, and leftover drain chemicals to its household hazardous waste point. Find your centre on the council website or the recycling pages for your nation.
Turn the stopcock and every isolating valve off and on twice a year so they work in an emergency.
Note what you did, the date and the part fitted in a page at the back of the boiler's instructions. The next plumber, or you next year, starts from facts instead of guesses.
Doing the small plumbing jobs: questions people ask
Bleeding radiators and topping up a sealed system's pressure, changing a tap washer or cartridge, cleaning or replacing a trap or waste, and clearing a blockage you can reach. The gas side, the mains and pressurised hot water systems are for professionals.
With the system cold, open the filling link as the boiler's instructions show, watch the gauge rise into its green band, and close the link. One maker's guide sets the band at 1 to 1.5 bar.
Isolate the water, take off the handle and remove the headgear or cartridge. Replace the washer on a washer tap, or clean or replace the cartridge on a ceramic one.
Pull out what you can see, plunge with the overflow blocked, and clean the trap. Chemicals are a last resort.
When the job touches gas, the mains, a pressurised cylinder or pipework that has to move, or when a fault keeps returning after a careful repair.
Locufy's UK price guide puts a plumber at £40–£90 per hour, typically £60 — the same three figures as the strip at the top of this page.
MORE GUIDES
More DIY guides
Sources — checked October 2026
- Worcester Bosch — system filling guide: the 1 to 1.5 bar band and the filling links
- Bristan — sink mixer installation and maintenance instructions: cartridge removal and cleaning
- Flat-bottom basin bottle trap installation instructions — fall to the wall and cleaning access
- HSE — domestic gas safety: frequently asked questions
- HSE — COSHH basics: hazardous substances
- HSE — electrical safety: frequently asked questions
- Gas Safety (Installation and Use) Regulations 1998, regulation 3
- Gas Safety (Installation and Use) Regulations (Northern Ireland) 2004, regulation 3
- gov.uk — Approved Document G: sanitation, hot water safety and water efficiency (England)
- Water Supply (Water Fittings) Regulations 1999, regulation 5
- Water Supply (Water Fittings) (Scotland) Byelaws Extension Order 2024
- Water Supply (Water Fittings) Regulations (Northern Ireland) 2009
- gov.uk — recycling collections: find your council (England and Wales)
- mygov.scot — find your council's recycling centre (Scotland)
- nidirect — recycling and reusing (Northern Ireland)
- B&Q — price check: radiator keys
- B&Q — price check: plungers
- B&Q — price check: tap washers
- B&Q — price check: adjustable spanners