How a house works, and where it switches off

Burst pipes rarely pick a good time. When one goes, there is one valve that stops the water to the whole house, one switch that cuts the power to every circuit, and one handle that shuts off the gas. If you've found them already, a burst costs you a mop and a plumber. If you're looking for them with a torch (flashlight) while the kitchen ceiling bulges, it can cost a ceiling, a floor and the wiring in between. This lesson finds all three with you, in a British home and an American one, and gives you the order to use them in. It also sets out how the course sorts every job, because "can I do this myself?" has a different answer for a tap, a fuse box and a gas pipe, and again in Wales and in Texas.

That box opens every lesson in this course, word for word. Its gas advice splits by country on purpose: British gas networks and American gas utilities give different first steps, and lesson 9, "Gas: the smell and the valve", sets them side by side. Follow your own country's.

Wherever this course states a law, one caution goes with it. This is general information, not legal advice. The rules differ between England, Wales, Scotland and Northern Ireland, and between US states and cities, and they change.

A house is four flows

Water in, under pressure. The water company's main runs under the street, and a pipe runs from it, across your land, into the house. The Consumer Council for Water (CCW), the statutory consumer body for water in England and Wales, splits the ownership at the boundary: the homeowner maintains the pipes "on private property up to the boundary of the road where the company’s water main is laid."³ On its way in, the supply passes a valve that WaterSafe calls "the point where you can shut off the water supply to your home or business."¹

Water out, by gravity. Drains don't push; they fall. Every sink, bath and toilet empties through a trap, the U-bend, which holds a plug of water that keeps sewer air out of the room. England's statutory guidance on drainage says traps "should retain a minimum seal of 25mm of water or equivalent" (about an inch) under working and test conditions, and that "discharge stacks should be ventilated", so the seals are not lost to pressure in the pipes.²¹ The American Society of Home Inspectors puts it plainly: "Vent piping allows air into the system so drains flow easily."²² This flow has no shut-off to find. Lesson 4, "Water out: traps, vents and blocked drains", is about what goes wrong with it.

Power in, through protective devices. Electricity arrives at a consumer unit (the British name; people still call it the fuse box) or a panel (the American one), and the devices in it do two different jobs. The US Consumer Product Safety Commission (CPSC) put the difference in 1989: a ground fault circuit interrupter (GFCI) cuts the power fast when current leaks where it should not, "whereas circuit breakers and fuses function primarily to prevent the home wiring system from causing a fire."⁸ Electrical Safety First (ESF), a UK electrical safety charity, says the British equivalent of the GFCI, the residual current device or RCD, "protects you from electric shocks if a product is faulty."⁷ So breakers and fuses are there mainly to protect the wiring, and RCDs and GFCIs to protect the person. Lesson 5, "Electricity: what trips, and why", takes that apart.

Fuel in, combustion products out. Gas (or oil, or wood) comes in, burns in a boiler, a furnace, a cooker or a fire, and what is left after burning has to leave by a flue (the pipe or duct that carries it outside) or a chimney. The gas has a shut-off at the meter. The way out has no switch to find, and lesson 11, "Carbon monoxide and the alarms that warn you", is about keeping it working.

That gives you three controls to find: water, power and gas.

Water: the stop tap and the main shut-off valve

In the UK

WaterSafe, the approved-plumber register run for the water industry, calls the control the internal stop tap, "also sometimes called a stop valve or stopcock". "It looks like a spout-less tap or lever and sits between two lengths of pipe acting as a connector." It is usually under the kitchen sink, and WaterSafe lists other places, from a garage to the space under the stairs.¹

Using it takes three facts, all WaterSafe's: "Turning the valve clockwise will close it"; it "may take a few minutes for the water to stop altogether"; and "Turn it on and off slowly, never force it." It gives the reason for the last one: "If you over tighten or use excessive force you may damage the stop tap." If it won't turn or won't shut off, WaterSafe's advice is to call a plumber.¹

A second stop tap sits outside, and it is not yours. CCW describes "The external stop tap usually located in the public footpath" as the water company's.³ It stops your water too, but it sits under a cover in the pavement, and in an emergency the one inside is the one you reach first.

The Met Office adds a habit: "Make sure you know where your stop tap is and check it’s working every six months."² This is a national weather service's advice, not a law. It gives no reason. This course's reading is that a valve you've tried recently is one you know will turn.

In the US

WSSC Water, a public water utility in Maryland, calls it the main water shut-off valve and says where to look by house type. In a house with a basement it is "typically located near the front foundation wall" and "typically within three to five feet of where the main water enters" (about 1 to 1.5 m). In slab-on-grade houses (built straight onto a concrete slab) and crawl-space houses (with a low open space under the floor) that have no basement, it is typically near the water heater or under the kitchen sink, "but anywhere is possible."⁵ WSSC also says "Every home was required to have a main water shut-off valve installed inside the home when it was built." It describes its own customers' houses, not a national rule, and an old house elsewhere may surprise you.

On operating it: "Round “wheel” handle valves will turn off by turning the handle clockwise. It may take two or more full revolutions." A lever handle is different: WSSC says it takes a quarter turn, "until the handle is not parallel with the pipe. It should stop at a ¼ turn." Turn it back on slowly, part of the way first.⁵ There is also an underground valve outside at the property line (at some homes the meter is out there too, in a pit, WSSC says). WSSC says that one is for a registered master plumber (a licensed plumber) or the utility, and that it charges a fee to operate it.⁵ One more detail matters in some houses: where a home has fire sprinklers, WSSC says you shut off the plumbing supply and leave the sprinkler pipe live, unless the sprinkler pipe is what is leaking.⁵

This course read no US source giving a householder the six-monthly check.

Two houses, first look

First, the simple case. A couple have just moved into a 1930s semi-detached house in England. The stop tap turns out to be where WaterSafe says it usually is, under the kitchen sink, behind a bottle of bleach and a bucket.

They turn it clockwise, slowly, with the kitchen cold tap open. The flow stops after a couple of minutes, which is WaterSafe's "may take a few minutes". Turning it back, anticlockwise, it goes stiff half a turn in, with the water flowing but not at full strength. WaterSafe says never force it, so they don't reach for pliers. They note on their shut-off map that it is stiff, and book a plumber.

Next they open the door of the consumer unit: a main switch, a row of circuit breakers and a button marked "T". ESF: "To check whether your consumer unit has an RCD, look for the ‘Test’ or ‘T’ button."⁶ They leave the button for lesson 5. Two breakers have no label, so they switch each off in turn, walk round to see what stopped, write it down, and switch it back on. This is labelling from the front of the box, this course's reading of the University of Georgia's home maintenance checklist, which says "label switches if needed".¹¹ A breaker that wouldn't go back on, or tripped again, they'd leave off and call an electrician about, as the box at the top says.

Electricity: the consumer unit and the panel

The main switch on a British consumer unit, and the main breaker in an American panel, cut the power to the house's circuits. A householder's work on the box stops there.

CPSC gives the reason in its leaflet on AFCIs, a type of breaker it says a householder shouldn't install: "Be sure to have a qualified electrician install AFCIs; do not attempt this work yourself. The installation involves working within electrical panel boxes that are usually electrically live, even with the main circuit breakers turned off."⁹ CPSC doesn't say what keeps the box live, and this course won't guess.

Two more facts go wherever electricity does in this course. First, a pocket "volt stick" that stays silent proves nothing: Britain's Health and Safety Executive (HSE), in its guidance for people who work on electrical systems, says the use of "non-contact devices such as 'volt sticks'" is not recommended for proving a circuit dead.¹⁰ Second, the course teaches no wiring at all. Lesson 22, "Who may do what: reserved work, and the argument about licensing", explains which electrical work the law lets a householder do in each UK nation and in five US places, and teaches the procedure for none of it. This is the course's decision about what a page can check, not a claim that the work is unlawful wherever you are.

So the front of the box is yours: the switches, the test button and the labels. Behind the cover is somebody else's.

Gas: the emergency control valve

In Great Britain and Northern Ireland

Cadent, the largest gas distribution network in Great Britain, describes the valve on its own meters in its guide to locating the meter. The meter may be inside (a garage, under the stairs, the kitchen) or outside, in a box that needs a key.¹² Then: "Open your gas meter box and locate the red tap handle near to the pipe. This is the emergency control valve (ECV). This handle will be aligned with the pipe; to switch off the supply you should turn it either 90 degrees to the left or 90 degrees to the right (a quarter turn clockwise or anti-clockwise)."¹² This is Cadent's description of the meters on its own network; this course didn't read other networks' guides.

Cadent's page on smelling gas says when to use it: open doors and windows, turn the gas off at the meter, and "If the gas leak is in a cellar or basement, do not enter and instead evacuate the building." The number is 0800 111 999, day or night.¹²¹⁴ In Northern Ireland, one gas supplier's advice (SSE Airtricity's) is the same shape, with its own number: turn the gas off at the meter "unless the meter is located in a cellar or basement", and phone 0800 002 001.¹³

Find the meter and the handle now, and look, but don't turn it to see if it moves. Gas isn't water: Cadent says that once it is off, "Don’t turn it back on until advised it’s safe to do so."¹²

In the US

The US utilities this course read give a different first step. Con Edison, in New York: "Leave immediately and take others with you." SoCalGas and Atmos Energy say the same: leave, and call from a safe distance.¹⁵ So in an American house, the course's advice is to know where the meter is and then leave it alone; this course read no US instructions for turning one off.

Gas and the law, in brief

This is general information, not legal advice.

In Great Britain, regulation 3 of the Gas Safety (Installation and Use) Regulations 1998 requires anyone who does gas work to be competent, and HSE's guidance says that includes people doing their own (regulation 3(1)). It requires employers and the self-employed to be on the Gas Safe Register, the HSE-approved register of gas businesses (regulation 3(3)). HSE's code of practice sets competence at an industry-recognised course followed by an assessment.¹⁶¹⁷ Northern Ireland's own 2004 Regulations have the same shape. So "it's illegal to do your own gas work" overstates the law, and "it's legal" leaves out the competence duty.

The advice is not in doubt. HSE: "HSE strongly advises that all gas appliances, flues and pipework should be installed, regularly maintained and serviced at least annually by a Gas Safe registered engineer."¹⁸ Gas Safe says "Don’t DIY with gas appliances, always use a Gas Safe registered engineer", and that a householder can do the tasks the maker's user instructions give the user.¹⁹ Lesson 10 has the rest.

When a pipe bursts

In the UK

What insurance covers is Personal Finance Fundamentals lesson 8, "Handing off what you cannot absorb".

In the US

This course read no US agency's burst-pipe order. The one American utility page it read, WSSC's in Maryland, says that once the main valve is closed you "Open a tub or sink faucet (hot and cold) on the highest level of the home to relieve pressure, and watch that spout to ensure that water has stopped flowing."⁵ This is one utility's advice to its own customers, not a national rule. After that, call a plumber; that step is this course's line, not WSSC's.

When the water reaches the electrics

This is the part that can hurt someone, and the Met Office's wording needs care. It says: "If water has leaked near your electrics, do not touch them and switch them off at the fuse box."² Read quickly, that tells you to go to the fuse box whatever state it is in. ESF's current advice after flooding adds a condition. "Switch off the electricity supply at the consumer unit/ fusebox, only if it is safe to do so." And: "Seek professional advice from a registered electrician if there is any sign of water inside the consumer unit/ fusebox or any signs of arcing or overheating." It also says: "Keep away from any exposed wiring as it may still be live."²⁰

Neither source says what makes it safe. So here's this course's own plain reading, not a quotation. Don't touch wet switches, sockets or fittings. Go to the consumer unit or panel only if the box and the wall around it are dry, with no water on it, in it or running towards it, and you can reach it without standing in water or touching anything wet. If you can't, keep clear and call an electrician. Both sources are British, and this course read no American source on water near a panel, so for a US panel this reading is the course's own. This is the idea behind First Aid and CPR lesson 2's danger step: make sure the power is off before you touch someone in contact with a supply.

The second house

Now a harder case: winter, in a two-storey house in the American Midwest. A pipe to the upstairs bathroom has split, and water is coming through the fitting of the hall ceiling light. The panel is on the basement wall, and when the owner opens the basement door there is already about an inch (2.5 cm) of water across the floor. The main shut-off valve is where WSSC says to look, near the front foundation wall, on the far side of the basement.

The light first: the switch and the fitting are wet, so the owner touches neither.

The owner gets everyone out of the wet hall and the basement, and calls their water utility, whose number is on its website or the bill, or a plumber. WSSC in Maryland, the one water utility this course read, says the underground valve at the property line is for the utility or a registered master plumber, and that WSSC charges to operate it.⁵ A utility in the Midwest may work differently, so ask it. Either way, the water can be stopped outside without anyone going into the basement. The owner also calls an electrician about the wet circuit and the panel: on this course's reading, water that may have reached a panel is an electrician's to look at (Electrical Safety First says the same of a British consumer unit).²⁰ Until someone closes that outside valve, the water keeps coming. This is the cost of a valve out of reach, and the reason to find out, before a winter, whether you could reach yours with the basement flooded.

Law or advice, whose, and where?

This is general information, not legal advice.

Household advice most often goes wrong one way: a rule from one place, or one kind of body, gets repeated as if it bound everyone everywhere. You have met three already. WSSC's "Every home was required" is about homes in one utility's area. The six-monthly stop-tap check is the Met Office's advice, not a law. And "gas work is illegal" is half of a two-part rule that binds businesses one way and everyone another.

So every rule in this course carries three things. Who says it: a law, a regulator, a charity, a maker about its own product, or a university's public advice service (in the US, an "extension service"). Whether it is law or advice. And where it applies: each UK nation by name, and the US federally or by named state or city.

Every job the course names carries one of three labels, too:

• Yours. The sources put it in a householder's hands, like turning off the stop tap.
• Yours, on conditions. Allowed if a named condition is met: "only if the box and the wall around it are dry", "not if the meter is in a cellar".
• Call someone. The law where you are reserves it, or every official source the course read advises against a householder doing it.

Where the law allows more than the advice, as with gas in Great Britain, the course gives both, law first, and the label follows the advice. So gas work is "Call someone" though the registration duty does not bind a householder.

What this course leaves out

No gas work and no wiring: the course explains the law on both, and stops at the front of the box and at the user instructions. Structural work, extensions, loft conversions, roofing and planning permission can need permission as well as professionals; these are named, not taught.

Fitting a lock. This course doesn't teach it: its research found no source on fitting or maintaining a lock to teach from, and this institute doesn't publish lessons written from general knowledge. For which locks and lights make a difference to burglary, Personal Safety lesson 5, "Home, the door and the doorstep", is the place to go.

Some jobs weren't researched and so aren't taught (tiling, flooring, appliance repair), and some belong to other courses: insurance and scams to Personal Finance Fundamentals, first aid to First Aid and CPR. Landlord and tenant law isn't taught either. If you rent, every exercise that changes anything says "if it's your home to repair, or your landlord agrees", and that's the course's own line, not a statement of tenancy law.

What people get wrong

"Clockwise opens it." It closes a stop tap or a wheel handle (WaterSafe, WSSC).¹⁵

"The stop tap in the pavement is the one to use." It's the water company's (CCW); in the US, the valve at the property line is for the utility or a master plumber (WSSC).³⁵

"Once the main switch is off, the fuse box is safe to open." CPSC says panels are usually live even with the main breakers off.⁹

"It's illegal to do any gas work yourself." It overstates the law, which binds businesses one way and everyone another (see "Gas and the law, in brief" above).

For your plan

The course project is a maintenance plan for your own home. This lesson adds three things: the shut-off map (where the three controls are, with photographs, and whether the stop tap turned freely), the emergency card (the burst-pipe order and the gas number or utility for your country), and the first item on the calendar: try the stop tap every six months, the Met Office's interval.²

Connections

Next, lesson 2, "Water in: supply, leaks and frozen pipes", goes to the other side of the stop tap, and lesson 3, "Taps and toilets", to the tap that drips and the toilet that runs. Lessons 5 and 9 come back to the consumer unit and the gas meter in full, and lesson 22 is where "law or advice, whose, and where?" becomes the whole subject.

Go deeper

• WaterSafe, "How can I locate my internal stop tap to turn off my water in an emergency?", free: a British account of where the stop tap is and how to use it.
• WSSC Water, "Find and Operate Your Home's Main Water Valve", free: a Maryland utility's guide for its own customers, with the valve set out by house type.
• University of Georgia Cooperative Extension, Home Maintenance Checklist, Circular 1082, reviewed June 2021, free: three pages of spring and autumn checks that the course project borrows from.

Sources

1. WaterSafe, "How can I locate my internal stop tap to turn off my water in an emergency?". Read: full text. No date shown; re-read 25 September 2026.
2. Met Office, "What to do if you have a frozen or burst pipe". Read: full text. No date shown. The burst-pipe order, the sentence on electrics, the six-monthly check.
3. Consumer Council for Water, "Who is responsible for my water pipes?". Read: full text. England and Wales.
4. Consumer Council for Water, "Winter advice". Read: full text. The burst-pipe steps and photographing the damage.
5. WSSC Water (Maryland), "Find and Operate Your Home's Main Water Valve". Read: full text, re-read 25 September 2026. About its own service area.
6. Electrical Safety First, "RCDs Explained" and "FAQ for Electrical Safety". Read: full extracted text of both; the RCD page's main explanatory body loads by script and did not come through.
7. Electrical Safety First, "Plugs and fuses". Read: full text.
8. US Consumer Product Safety Commission, news release 89-031, "Easily Installed Device Protects Family Against Electrocution", 28 May 1989, Internet Archive capture 20260311171701 of cpsc.gov. Read: full text.
9. US Consumer Product Safety Commission, Publication 5133, "Preventing Home Fires: Arc Fault Circuit Interrupters (AFCIs)", dated R042012. Read: full text.
10. Health and Safety Executive, Electricity at work: Safe working practices, HSG85, third edition, 2013. Read: the whole PDF extracted; "Proving dead" paragraphs 53 to 55 read. Workplace guidance, used here only for what it says about non-contact testers.
11. P. R. Turner and L. Bailey, Home Maintenance Checklist, Circular 1082, University of Georgia Cooperative Extension, reviewed June 2021. Read: full text.
12. Cadent Gas, "What to do if you smell gas" and "Locating your meter and turning off the gas". Read: full text of both, 25 September 2026. Cadent's network in Great Britain.
13. SSE Airtricity Gas Supply NI, "In an Emergency". Read: full text, re-read 25 September 2026. Northern Ireland.
14. National Gas, "Emergency Contacts". Read: full text, re-read 25 September 2026.
15. Con Edison, "Gas Safety"; SoCalGas, "Natural Gas Leaks"; Atmos Energy, "Recognizing a leak". Read: full text of each. US utilities, each about its own customers.
16. The Gas Safety (Installation and Use) Regulations 1998 (SI 1998/2451), regulation 3. Read: in full, re-read on the live page 25 September 2026. Extends to England, Wales and Scotland.
17. Health and Safety Executive, Safety in the installation and use of gas systems and appliances, L56, fifth edition, 2018. Read: guidance paragraphs 52 to 55, ACOP paragraph 81, guidance paragraphs 82 to 87, and the glossary entry "gas engineer".
18. Health and Safety Executive, "Gas safety: home owners". Read: full text.
19. Gas Safe Register, "Don't DIY when it comes to gas appliances", Internet Archive capture 20251023004454 (the live site blocks automated readers). Read: full page text of the capture.
20. Electrical Safety First, "Electrical safety after a flood". Read: full text, 25 September 2026. Written for flooding; it names a burst pipe as a case of clean-water damage.
21. HM Government, Approved Document H, Drainage and waste disposal, 2015 edition, for use in England. Read: Section 1, paragraphs 1.1 to 1.34, and Table 1.
22. American Society of Home Inspectors, "Plumbing System". Read: full text. A US trade body for home inspectors.