Drainage: Soil and Waste Pipes, Vents, Manholes, Gullies and Rainwater

Its three tools

Open **CAD tools** in the tool rail and then **Drainage**. The group has three tools, and each has a command you can type.

**Catalogue** (`DRAINAGE`): browse the trade's fittings by system, with each one's plan symbol. Picking one arms Place with it.

**Drain** (`DRAIN`): draw a run. Click each point; press Enter to finish. The run starts on the trade's usual size, and its size, system and levels are in its panel afterwards.

**Place** (`PLACEDRAIN`): put down the fitting you picked. Each fitting stands at its usual height, which its panel can change.

A run snaps to the connection points (ports) of fittings, so a pipe or a cable that starts on a fitting is joined to it. A fitting that should be connected and is not is listed in the Issues tab as not connected.

What is in the catalogue

**Fixtures**: WCs, wash hand basins, baths, showers, kitchen and utility sinks, washing machine and dishwasher connections, bidets, urinals, traps, floor traps and wastes.

**Soil and vent**: vent stacks and terminals, air admittance valves, cleanouts, septic tanks.

**Below ground**: inspection chambers, manholes, inspection pits, rodding eyes, sumps and pumps.

**Surface water**: gullies, soakaways, drainage trenches and interceptors.

**Rainwater**: downpipes, roof drains and hoppers.

Falls and levels

**Gradient**: a drain's panel shows its fall as a gradient, and the **Invert at start** and **Invert at end** that follow from it.

**Chambers**: a chamber's cover level is where the ground is; its invert comes from the drains running into it, and its depth is the difference. Move a chamber further away and it goes deeper, because the fall is held.

**Branches**: a branch joins a main above it, never below.

Generate the drains

Settings › Structure › **Drainage** runs the soil, waste and rainwater from the fixtures in the rooms out to the boundary that faces the street, where the sewer is.

Name the rooms first: it finds fixtures in rooms named as a bathroom, a kitchen or a utility. Every invert comes from one fall, and what it writes is marked as proposed.

Generating again replaces its last run; what you drew stays. With no plot boundary it stops a fixed distance from the house and says so. See [Site plan](/docs/site-plan).

Tip: nothing generated is designed. It is a first layout to check and change.

The checks

**Falls**: a drain with no fall, too flat, too steep, or too shallow under the ground.

**Chambers**: a chamber too small or of the wrong kind for its depth, an inverted chamber.

**Stacks**: a soil stack that does not line up from storey to storey.

**Rainwater**: a gutter too small for the roof that falls on it, a missing downpipe, downpipes too small or too far apart.

In 3D and on paper

**3D**: runs are built as real cables, pipes and ducts at their levels, and fittings stand at their mounting heights. In 3D you can drag a run's end or its body, and it snaps to corners and to other fittings' ports.

**Through walls**: a run that crosses a wall or a floor cuts its own hole through it, and the hole moves with the run.

**Showing and hiding**: the Layers tab has a switch for each trade, and an X-ray switch that shows the services through the building.

**Sections**: a run cut by a section is drawn as its section, and the ones beyond it along their line.

**Schedules**: the Schedules tab lists runs by size, fittings by kind and boards by circuit. See [Sheets and schedules](/docs/sheets-and-schedules).

Read next

• Plumbing and heating
• Site plan
• Roofs
• Checks and issues

Frequently asked questions