Domestic plumbing done properly

Cue 1 Five fluid categories as a rising bar, with an everyday example on each.

AMARA 00:00 Do I need to be registered to do plumbing in my own house?

NADIA 00:05 For most domestic water plumbing, no. And that surprises people, because everybody assumes plumbing is like gas.

AMARA 00:12 So it is unregulated?

NADIA 00:13 Not remotely. There is no registration requirement but there absolutely is law. The Water Supply Water Fittings Regulations 1999, and the byelaws in Scotland, apply to anybody who installs or alters a water fitting. Breach them and it is a criminal offence with a fine attached.

AMARA 00:32 What are they actually for?

Cue 2 Air gap versus double check valve, with the valve failing and the gap not.

NADIA 00:34 One thing above all. Stopping contaminated water getting back into the drinking supply. Everything else in them is secondary.

AMARA 00:41 Backflow.

NADIA 00:42 Backflow. And once you understand that it is the point, the whole rulebook stops feeling arbitrary.

AMARA 00:48 Then teach me the framework.

NADIA 00:50 Five fluid categories. One is wholesome water as supplied. Two has changed in taste, smell or appearance but is not a health risk, so warmed water. Three is a slight hazard, a heating system with no additives, a domestic washing machine.

Cue 3 Outside tap and hose in a water butt, with the backflow path highlighted in red.

AMARA 01:06 And the serious ones?

NADIA 01:08 Four is a significant hazard: inhibitor, antifreeze, pesticide. Five is the serious one, and it means human or animal waste or pathogens. A WC. A bidet. A trough. A sink you have been cleaning in.

AMARA 01:22 How does the protection change?

NADIA 01:24 It rises with the category, and at category 5 you need the one protection that cannot fail mechanically. An air gap. A physical vertical gap between the outlet and the highest the dirty water could ever reach.

AMARA 01:39 Why not just fit a good valve?

Cue 4 Street main bursting and the pressure dropping, siphoning the system backwards.

NADIA 01:41 Because a valve is a mechanism, and mechanisms fail. Grit, scale, age. An air gap is a piece of empty space and it has never failed in the history of plumbing.

AMARA 01:54 Give me the everyday example, because this still feels theoretical.

NADIA 01:58 Your outside tap. Hose screwed on, other end lying in a water butt, or a pond, or a bucket you have been washing the car in.

AMARA 02:08 That is most houses in Britain.

NADIA 02:11 It is. And that is a direct path from category 5 water into the drinking main, waiting for a pressure drop.

Cue 5 Notifiable work list: bidet, irrigation, large pond, large bath.

AMARA 02:19 How would the water go backwards though? It comes out under pressure.

NADIA 02:24 Until it does not. A main bursts down the street, the pressure drops, and the system siphons. That is not a hypothetical, it is exactly how contamination incidents happen and why undertakers care so much about it.

AMARA 02:39 So what does that outside tap need?

NADIA 02:42 A double check valve, which is two check valves in series and protects to category 3, plus the discipline not to leave the hose end submerged. About eight pounds of fitting, and it is the most common breach in the country.

AMARA 02:58 Is there anything I have to tell the water company about before I do it?

Cue 6 Isolating valve fitted at an appliance, with the whole house staying live.

NADIA 03:04 Yes, and people miss this. Certain work must be notified in advance and they can refuse consent. A bidet with a flexible hose. Any garden irrigation system. A pond or pool over ten thousand litres. A bath over two hundred and thirty litres.

AMARA 03:21 A big bath needs permission?

NADIA 03:23 It does, because of the draw on the main. It catches out a lot of bathroom installers doing a high end job.

AMARA 03:32 Last thing. Fittings.

NADIA 03:33 Use ones approved for potable water, so WRAS approval or another recognised UK scheme. And fit an isolating valve at every appliance, because the next person to repair it will otherwise be draining the whole house, and quite often that next person is you.

Cue 1 Gas Safe boundary card: what is legal, what is a criminal offence.

AMARA 03:51 Before we start on joints, what is the hard line?

NADIA 03:55 Gas. Under the Gas Safety Installation and Use Regulations 1998, only a Gas Safe registered engineer may work on gas fittings and appliances.

AMARA 04:04 Not a competent amateur.

NADIA 04:06 Not a competent amateur, not a confident plumber, not you. That includes the gas supply to a boiler, gas cookers, gas fires and the pipework serving them. It is a criminal offence, it voids buildings insurance, and carbon monoxide from bad gas work kills people every single winter.

AMARA 04:25 Is there anything I may do?

Cue 2 Three joint types in cross section with the failure mode animated on each.

NADIA 04:27 Turn it off in an emergency, and work on the water side of a wet system. That is the whole boundary and it does not move.

AMARA 04:38 And if I smell gas?

NADIA 04:40 Do not touch any electrical switch, not even to turn a light off. Open windows, turn off at the meter if you can safely reach it, get out, and ring 0800 111 999 from outside.

AMARA 04:54 Right. Joints. There are three kinds and I have never known which to use.

NADIA 04:59 Match the joint to where it is going. Soldered capillary joints are the strongest, cheapest and neatest, so they belong anywhere the joint is going to be forgotten about. Inside a wall. Under a floor.

Cue 3 Capillary action drawing solder into a heated fitting.

AMARA 05:13 What makes a solder joint fail?

NADIA 05:16 Three things, and it is always one of them. The pipe was not clean. There was water in the line so it never got hot enough. Or somebody nudged it while it was cooling.

AMARA 05:29 How do I get it right?

NADIA 05:32 Clean pipe and fitting to bright copper, flux both, and then heat the fitting, not the solder. Let capillary action draw it in. If you are melting solder with the flame you are doing it wrong.

AMARA 05:46 Compression?

Cue 4 Crushed olive from over tightening beside a correctly seated one.

NADIA 05:46 Demountable, no flame, so it is right where a blowtorch is dangerous or where you might need to take it apart. And it is ruined by exactly one thing: over tightening.

AMARA 05:59 Everyone over tightens.

NADIA 06:00 Everyone does, because it feels like security. You crush the olive out of shape and it will never seal again. Tighten until it bites and then usually not more than a turn. Then test it rather than heaving on it for insurance.

AMARA 06:17 And push fit? Real plumbers seem sniffy about it.

NADIA 06:20 Some are, and they are wrong. It is fast, it tolerates a damp pipe, and for a repair under a floor on a Sunday it is excellent. It fails for three reasons and all three are avoidable.

Cue 5 Pencil insertion mark disappearing as push fit pipe seats fully.

AMARA 06:35 Which are?

NADIA 06:36 The cut was not square. The pipe was not pushed fully home. Or somebody left the insert out of plastic pipe. So: deburr it, mark the insertion depth on the pipe with a pencil, and push until your mark disappears.

AMARA 06:52 Let us talk about finding leaks. Water appears on a ceiling and I have no idea where it came from.

NADIA 07:00 Then read the timing first, before you open anything. Constant drip whatever you do means the supply side, because that is under pressure all the time. Only when a tap runs or an appliance drains means the waste side.

AMARA 07:16 And only when the heating is on?

Cue 6 Water tracking along a joist and dropping away from the source.

NADIA 07:18 A heating circuit joint opening up as it expands. That one drives people mad in summer because it does not leak at all.

AMARA 07:28 What about the ceiling stain?

NADIA 07:30 Almost never directly under the source. Water tracks along a joist and drops at the first low point. So look higher and to one side, and do not start cutting the ceiling out where the stain is.

AMARA 07:44 Last thing. What is worth learning to do myself?

NADIA 07:48 Tap washers and ceramic cartridges, traps, toilet fill and flush valves, isolating valves, flexible connectors and blockages. That is the very large majority of every callout a domestic plumber attends.

AMARA 08:00 Any habit that helps?

NADIA 08:02 Three. Fit an isolating valve while you are in there. Photograph it before you dismantle anything. And lay the parts out in the order they came off. The plumber's bill is rarely the part.