Driveway Drainage Johannesburg

Johannesburg's rain

Johannesburg gets most of its rain between October and March, much of it in short, heavy afternoon and evening thunderstorms, and December is usually the wettest month. Climate averages for O.R. Tambo show April to August as markedly dry. The South African Weather Service describes October as the start of the rainy season for the summer rainfall region. That pattern has two consequences for paving: it is best built in the dry months, and it is tested in the wet ones.

Sources: timeanddate.com, Johannesburg climate averages (O.R. Tambo, 1992-2021); South African Weather Service media release, 12 November 2025

Falls: the slope you do not notice

Paving should never be perfectly flat. It needs a fall, a slight slope that carries water off the surface, towards somewhere it can go. The right fall depends on the paver and the site, and you should ask your contractor what fall they will build in and where it leads. We do not publish a single figure here because the ones that circulate in the paving trade are usually from contractors' marketing, not from a standard document we have checked.

The direction matters as much as the amount. Paving must fall away from the house, away from the garage door and away from the neighbour's property, towards a drain, the street or a planted area that can take the water.

Channel drains and outlets

Across the garage door: the classic fix where a driveway falls towards the house.
Across the gate: to stop water running out of, or into, the property along the drive.
Part way down a steep drive: to break up the flow before it builds speed.
At downpipes: roof water should go to a proper outlet, not into the paving bed.
Permeable paving: special pavers and a purpose-built base that let water soak in, used where the design allows. A contractor should explain whether it suits your ground.

Sources: Bosun, South African permeable paving guidelines

What the rules say about storm water

South Africa's national building regulations deal with stormwater disposal in SANS 10400 Part R. A plain-language summary of Part R notes that the regulations give clear guidelines for stormwater control and that these do not include discharging water into your neighbour's garden. If your paving project changes how water leaves your property, ask the contractor how it complies, and whether any approval is needed.

Sources: SANS 10400 Part R, stormwater disposal (summary)

Slopes and ground

Steep driveways are common in Northcliff, Bryanston and parts of Sandton and Roodepoort. On a slope, water moves faster and carries joint sand with it, edges are pushed downhill, and the base at the bottom of the drive gets the most water. Good practice is a pattern that locks blocks together, strong edge restraint and drains that slow the water down. On dolomitic ground, found in parts of the West and East Rand, engineers stress that concentrated water is a trigger for internal erosion, so spreading and piping water away is especially important.

Sources: Stiff, Booyens and Mmileng (SRK Consulting), Protecting infrastructure from dolomite-related subsidence and sinkholes, Civil Engineering, April 2025

Checklist for your quote

Which way will each part of the paving fall?
Where does each low point drain to?
Are channel drains included, how long and where?
Where do the downpipes discharge now, and after the job?
Will the work send more water onto a neighbour or the street?

See driveway paving and paving design and layout for more.

Frequently asked questions

Why does water run into my garage?

Usually because the driveway falls towards it with no drain across the door. A channel drain and corrected falls are the usual fix.

Can my neighbour's paving drain onto my property?

A plain-language summary of SANS 10400 Part R says the stormwater guidelines do not include discharging water into a neighbour's garden. For a dispute, get proper advice.

When is the best time to fix drainage?

Before the storm season, ideally in the dry months from about April to August.

Driveway drainage in Johannesburg: slopes, falls and channel drains