On site, they're called buried services or underground utilities: the pipes and cables of the water company, the electricity network, the gas network, telecoms and sewers. The network owners keep records of their own assets. What happens after the meter or the property boundary, though, is often written down nowhere: the cable to the shed, the drain from the kitchen, the overflow from the rainwater tank, the land drain laid around the foundations.
Nobody will draw that plan for you. You need it every time someone digs: a patio, a pool, an extension, a fence, planting a tree, tracking down a leak or a blocked drain. And it's worth something the day you sell the house.
Why draw this plan now
The best time to record a pipe is when the trench is open. The second best is before the next job. A few situations where the plan saves you trouble:
- Before you dig foundations, a pool or fence post holes: a cut cable is a power cut at best, an accident at worst.
- When a drain blocks: knowing where the inspection chambers are saves the drainage engineer half a day.
- Before an extension: building over a sewer or a water main means diverting it, or getting the water company's agreement, and you'd rather know before the quote.
- For a tradesperson who doesn't know the house: they see the routes before they turn up.
Public and private networks: who knows what
There are two worlds to tell apart.
The network owners' assets, up to the connection point or the meter. Before any digging, check with them. In the UK, the free LinesearchbeforeUdig service (lsbud.co.uk) lets homeowners check a planned job against the assets of the network owners that are members. Not all of them are: it's up to you to contact the others in your area. Your water company keeps the records of public sewers and water mains. In Ireland, ESB Networks and Gas Networks Ireland each run their own request service for maps of their networks. The network owners reply with their own plans.
Private services, on your plot, after the meter. These don't appear in any of those records. That's what your plan is for. Add the public services up to the meter too, as shown by the network owners: you'll have everything in one place.
What to look for at your place
| Service | Where to start looking | What to record first |
|---|---|---|
| Drinking water | Meter, outside tap, where the supply enters the house | Route, depth, material |
| Foul drains and sewer | WC and kitchen outlets, inspection chambers, connection to the road | Chambers, direction of flow, diameter |
| Surface water | Downpipes, rainwater tank, overflow | Where the overflow goes (sewer, soakaway, ditch) |
| Electricity | Consumer unit, cables to shed, gate, lighting, car charger | Route, depth, what the cable supplies |
| Gas | Meter, entry into the house | Route up to the meter |
| Fibre and telecoms | Entry box, duct from the road | Route of the duct |
| Land drainage | Base of below-ground walls, drainage chamber | Route, outfall |
| Irrigation | Valves, timer, sprinklers | Route of the lines and valves |
| Heating, ground source | Heat pump, buried collector loops | Footprint of the loops |
Add the structures: rainwater tank, septic tank or small sewage treatment plant, manholes and inspection chambers, well, soakaway, meters. They're often what lets you work out the route of the pipes.
What to record for each pipe
A line on a plan isn't enough. For a tradesperson to use it, each pipe needs a few pieces of information:
- The service: drinking water, foul water, surface water, electricity and so on. A rainwater pipe and a foul drain look very alike once they're buried.
- The route, point by point, with the changes of direction.
- The depth, in centimetres, measured wherever you could see it: in a chamber, an open trench, an exposed joint.
- The diameter, in millimetres. On plastic pipes it's often printed on the pipe itself.
- The direction of flow for services that work by gravity, such as foul drains and surface water.
- How sure you are. This is the most important point. “Measured during the 2024 works” and “assumed, straight line between two chambers” aren't worth the same. Note it for each section.
Always say where you measured the depth from, ideally from finished ground level. If the garden level has changed since the pipe was laid (built up, a new patio), the pipe is no longer at its original depth: a classic trap.
Trace a route without digging everything up
You don't need to dig a trial trench everywhere. A few methods, from the simplest to the most technical:
- Lift the inspection chamber covers. You can see where the pipes come in and where they leave. With a tape or a straight batten, measure the depth to the bottom. Between two chambers, a drain often runs in a straight line, but not always: record it as “assumed”.
- Follow the visible points: downpipes, pipes coming out of walls, meters, outside taps, stopcocks, tank lids.
- Dig through your records. Photos taken during building work, even on a phone, often show open trenches. Drawings from past planning applications, a builder's as-built drawings and connection invoices are useful clues too. Ask the previous owner.
- Call in a professional for what's still unclear: a CCTV drain survey by a drainage company or a plumber, or a cable locator survey.
Many services have a coloured warning tape laid above them, which helps identify them as you dig. The colours follow conventions that aren't the same everywhere, and old installations don't always follow them: don't rely on colour alone.
Draw it in Architektor
Switch to the underground level, the one for utilities. The house and the garden stay visible, faded: you place the pipes relative to the walls and the trees, not in empty space.
- Pipes are drawn with the Pipe tool (U key): click each point along the route, then double-click or press Enter to finish. Choose the service from drinking water, sewer / wastewater, stormwater, electricity, gas, fibre / telecom, drainage, irrigation, or heating / geothermal. Each service has its own colour. Set the diameter in millimetres and the depth in centimetres.
- Structures go in with the Tank / manhole tool (K key): rainwater tank, septic tank or treatment plant, manhole or inspection chamber, well, soakaway, meter, with their dimensions, their depth and, for a tank, its volume.
- The Notes field of each element takes whatever doesn't fit in a box: “measured in 2024”, “assumed”, “2.5 mm² SWA cable to shed”. These notes stay private: they're never shown in a share.
- Statuses work here too: a planned connection is drawn as “To build”, a section that will be removed as “To demolish”.
Share it with a plumber or a groundworker
A map of buried services is only useful if it ends up in the hands of the person digging.
The share link is the simplest. Choose “Underground utilities” under “Who is it for?”: only the utilities level is shown, without the details of the house. The person opens the link in their browser, without creating an account. They can zoom, measure a distance and pin a comment in the exact spot (“the pipe is deeper here”). You choose whether the link follows your changes live or shows a frozen version, and you can deactivate it at any time.
The PDF to scale is for the site. Hide the other levels, keep the utilities and perhaps the garden for reference, and export to A3 or A4. The title block shows the scale and the north arrow: you can measure a distance off it and set it out on the ground. Print it out; paper is still what copes best with mud.
Ask the tradesperson to correct the plan with you after they've been. They're the one who saw the pipes.
Keep the plan up to date
The plan goes out of date with the next job. One habit is enough: every time a trench is open, take a photo with a tape measure extended in the hole so you can read the depth, and a wider one to show where it is. Update the plan that same evening, then save a named version, for example “Shed cable, March”. You can always go back to the previous state.
This plan then becomes the base for your other projects: placing a swimming pool clear of the sewer, planning an extension without building over a pipe, or planting a tree away from the drains.