Apr 032013

Stormwater Disposal-Part R, What the Regulations Say

a street totally flooded.

When the heavens open up and flood gardens and roads, you rely on storm water drains to deal with the excess water.

A flooded street overflows into a residential property

The house on the far side of the road was totally flooded during a major downpour. The question is, whether the house was built with sufficient drainage to be able cope with all the storm water.

Property owners are responsible for the removal of storm water from their property. They may NOT simply discharge excess water onto adjacent land or into the street unless this is permitted by neighbors and/or the local council or municipality.

SANS 10400: Part R Stormwater Disposal

The law is very clear on the issue of stormwater disposal, although sites used exclusively for “dwelling houses” and dwelling units (defined as “one or more habitable rooms and provided with sanitary and cooking facilities”) are not as carefully controlled as larger buildings.

Note that a dwelling house is (in terms of the legislation) a single dwelling unit and any garage and other domestic outbuildings that are situated on the site. A dwelling unit contains one or more habitable rooms and it provided with both cooking facilities and adequate sanitary facilities.

Part R of the Act states: “The owner of any site shall provide suitable means for the control and disposal of accumulated stormwater which may run off from any earthworks, building or paving.”

The legislation also states that the “means of stormwater disposal” used may be addition to, or in combination with any drainage that may be required in terms of F4(2). SANS 10400: Part F Site Operations is described in more detail in the section on site operations on this website. The relevant section – 4(2) – is also discussed below.

These legal requirements will be “deemed to be satisfied” if the stormwater is provided in accordance with SANS 10400-R (the SANS drawn up by the SABS for “The application of the National Building Relations”, Part R), which is available from the SABS online store  for R174.42 incl. VAT.

SANS 10400, Part R deals with all types of stormwater disposal, including rain water from gutters, downpipes, roofs, and paving, and any other excess water that may accumulate on the property. It refers readers to Part H, Foundations stating that it is essential to have good, effective drainage of areas that are in close proximity to buildings, to ensure that ground movement is minimized.

Scope of Part R, Stormwater Disposal

The focus of Part R is on the disposal of stormwater on individual sites, but also included interconnected complexes that have multiple dwelling units, including both cluster homes and retirement, village-type properties where management of common property is often controlled by a management body of some sort.

Two types of stormwater system are defined in the regulations:

  1. Major stormwater systems that cater for severe, infrequent storm events
  2. Minor stormwater systems that cater for frequent storms of a minor nature

The rational design of these systems – if required – must be undertaken by “a competent person involving a process of reasoning and calculation and which may include a design based on the use of a standard or other suitable document.” The concept of a competent person is discussed in some detail in another article. However Part R states that a competent person required for stormwater system designs must be a civil engineer who is registered in terms of the Engineering Profession Act 2000 as a professional engineer or professional engineering technologist. Alternatively this person must have a tertiary qualification (a degree or a diploma) in civil engineering.

The legislation (the Act itself rather than the deemed to satisfy rules compiled by the SABS) states that it is the right of the local authority to demand that storm water disposal is provided in accordance with “an acceptable rational design prepared by an approved competent person” So if your local authority is of the opinion that a qualified person should design a stormwater disposal system for your property they must notify you (or the owner of the property) and explain their reasons in writing, and demand that plans and particulars of “a complete stormwater control and disposal installation” for the site and any buildings on it, are submitted for approval.

Stormwater Control and Disposal

The legislation states that the regulations should not be interpreted specifically as requiring roof gutters and downpipes if another suitable means of drainage has been provided to remove or disperse rainwater from the roof of the building. There are alternatives that architects sometimes prefer.

As always, the deemed to satisfy rules take this further. These state that any stormwater that emanates (or flows) from the roof, paving or any area that is in the immediate vicinity of a building shall not cause damage to the interior of the building, its structure or its structural elements. Steps must be taken to ensure that water does not accumulate in a way that “unduly inconveniences” the occupants of any building.

Part R also specifies other requirements of stormwater disposal arrangements. The system:

  • must not undercut foundations by erosion or flooding
  • must drain away from all buildings
  • must not allow water to accumulate against or close to external walls
  • must make provision for the drainage of any sites on the property that become waterlogged at any time
  • must be capable of being easily maintained and cleaned

Part R also specifies some of the disposal arrangements that need to be addressed, specifically:

  • those that allow rainwater to flow off the roof and away from the building, including roof valleys, gutters, and downpipes
  • those that channel surface water into stormwater drains that are either on the surface or below-ground, or channels – depending was is needed to remove stormwater from the site or to another part of the site where it will not affect the buildings

Ultimately, all drainage must  be shown on plans submitted to the local authority, and it is up to the local authority to decide whether these are suitable and adequate for each individual site. Also, it is the decision of the local authority whether stormwater may discharge into a stormwater system that is provided for a public road, or any servitude, or onto the street.

One of the major issues is people simply discharging their stormwater onto neighboring properties.  While the Building Regulations do not state that this may not be done, the Building Regulations do give very clear guidelines for stormwater control and disposal, and these DO NOT include the discharge of water into your neighbour’s garden! 

Stormwater Disposal in Interconnected Complexes

While the regulations and deemed to satisfy requirements described above apply to all properties, including complexes that are interconnected, there are additional requirements for the latter. For instance it is essential that stormwater is “controlled, safely routed and discharged from interconnected complexes without unduly eroding land, unsurfaced roads or water courses, contamination water resources or compromising environmentally sensitive areas identified in environmental impact assessment reports.”

In addition, both major and minor systems must be designed to cope with design flood recurrence intervals of both 50 and two years. At present there is legislation that requires flood lines for “townships” to be determined for 100-year recurrence intervals. This is because the storm water flow from 100-year floods is typically 25 percent greater than for 50-year floods. Part R states that major storm systems can be designed for a 50-year flood provided that the certified 100-year flood lines remain unchanged. This is very important.

Other requirements include:

  • the creation of terraces for dwelling units, where needed, that will allow the water to drain by gravity
  • the avoidance of erosion caused by too much water
  • specifications for the velocity of stormwater flow in road-edge channels constructed as part of a minor stormwater system
  • the need for channels built in soil that is susceptible to erosion to be lined
  • a specification that pipes in servitudes must have a diameter of no less than 300 mm

There is also a table that specifies minimum stormwater pipe gradient in relation to the diameter of the pipe. So if the minimum 300 mm pipe is used the desirable minimum gradient is 1 in 80, and the absolute minimum gradient is 1 in 230. If the maximum 1 200 mm diameter pipe is used, then the desirable minimum gradient is 1 in 520, and the absolute minimum gradient is 1 in 1500.

Gutters and Downpipes

There are some important specifications that relate to gutters and downpipes, including a table that gives roof, eaves and valley gutter sizes. In summer rainfall regions, the internal cross-sectional area of a valley or gutter per square metre of the roof plan area served (per square mm) is 140; in winter rainfall regions this is 80; and in areas where it rains all year round, the figure is 115.

In addition, the internal cross-sectional area of downpipes shall be not less than 100 square mm/square m of roof plan area served by such downpipe, or 4 400 square mm.

SANS 10400: Part F Site Operations F4(2)

Part F4 deals with preparation of a site that is to be built on. Point (2) states that when a building is to be erected on a site that is waterlogged or saturated with water, or where any building is going to be situated so that water will drain naturally towards it, drainage must be provided to direct the water away from the site or building, to a storm water drain, or somewhere that it can be disposed of in some other safe and approved manner.

Note that these requirement are in addition to Part R.

SANS 10400: Part L Roofs

This part of SANS 10400 is dealt with elsewhere on this site in the section on Roofs.

Waterproofing and runoff are dealt with in some detail in the relevant SANS for The application of the National Building Regulations.

Other SANS that deal with Stormwater Drainage

Additional SANS that deal with storm water drains and gullies are intended for the use of civil engineering construction and include:

  • SANS 1200 LE – Standardized specification for civil engineering construction Section LE: Stormwater drainage.

This is a drawing from the above SANS that shows how a precast concrete manhole for storm water should be built.stormwater disposalstormwater disposal

  • SANS 10120 – A Code of practice for use with the above, including:
  1. Part 2: Project specification Section LE: Stormwater drainage
  2. Part 3: Guidance for design Section LE: Stormwater drainage
  3. Part 4: Typical schedule of quantities Section LE: Stormwater drainage
  4. Part 5: Contract administration Section LE: Stormwater drainage


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  128 Responses to “Stormwater Disposal”

Comments (127) Pingbacks (1)
  1. Hi there
    My neighbour next to us has covered the manhole with paving. Telkom came out to install lines at our house and could not get the Telkom lines through the manhole as the Telkom wires run underground. Is he allowed to cover up a manhole? Telkom doesn’t want to get involved and tell him that there is a problem and our Estate Manager says it Telkom problem.

    • Manhole as in what? Surely not sewerage? I’m confused. But no, any type of manhole MUST be accessible otherwise why would it be a manhole? If it is a Telkom issue then it doesn’t relate to National Building Regulations. What puzzles me further is that you have posted this in Stormwater Disposal. Am I missing something?

  2. Hi
    Question; I want to get rid of the rainwater coming from my corrugated iron roof (344 m2 of roofing). Am I allowed to drain into the sewerage system? The slope of the property makes it difficult to drain it into the street. Can someone give me n answer on this?

  3. Hi, We have a house behind us where the owner runs his business from. He recently bought the premises and has done various renovation to the property. Our house has a cottage and the stormwater from this house accumulates behind the cottage and often floods the cottage. The owner of the company refuses to sort this out. He initially had plans to extend and build on his property further and we refused to sign the plans. He states that if we do not sign the plans he will not fix the water problem. What I would like to know is if that water needs to be sorted out by him and if there is anything I can do legally to get him to sort it out.

    • That’s blackmail! The law is very clear, that the “owner of any site shall provide suitable means for the control and disposal of accumulated stormwater which may run off from any earthworks, building or paving.”
      The deemed-to-satsify requirements as determined by the SABS are discussed on this page. Start by reporting him to the local authority; you might even find that he didn’t have plans to do the renovations!

  4. Hi. I recently built a house in a new complex (full title). My plot is at the lowest point of the complex and is at a dead-end. When it rains the road water from the entire complex flows towards my house and builds up at the wall by the dead-end. Last week it built up so much that the water erroded the soil and gushed under my boundary wall and driveway paving, down the driveway and into the house. The builder says it is my fault and I need to ensure that I dispose of any water coming down the driveway. My opinion is that all complex water should not be directed to my house in the first place and the builder needs the ensure there is sufficient drainage on the road of the complex. Please give me your views?

    • I agree with you 100%. The law is very clear on this: “The owner of any site shall provide suitable means for the control and disposal of accumulated stormwater which may run off from any earthworks, building or paving.” Part R of SANS 10400 gives guidelines on how this should be done (this page has some commentary on the guidelines). What is clear is that people above you need to take responsibility for stormwater from their properties.

  5. Hi

    We have been in our house for about 2 years now. We have recently done the paving as well as new gutters and all the trimmings. We stay on a terraced property and are 3rd from the top. To date our neighbour above us has 5 holes through the wall on his side (higher side) that dumps huge volumes of water on our property, logging it for ages.

    Our neighbour at the bottom has one hole coming from us and he`s now moaning about the volume of water coming through. I asked him to cut another hole through the property at the back to relieve some of the water, but he said the neighbour behind him is moaning with him.

    Our properties slope down from the street inwards, so the natural catchment point is in our far corner. I don`t want to tell my neighbour above us that he can`t flow water through anymore,but if it`s staying on my side then I don`t have a choice. Help?

    • Gary if you have read the article on this page you will see that the law states: ““The owner of any site shall provide suitable means for the control and disposal of accumulated stormwater which may run off from any earthworks, building or paving.” SANS 10400 – Part R: Stormwater Disposal gives guidelines on how this should be done. It is not acceptable to simply make holes in your wall and drain to a lower neighbour.

  6. HI

    I live in a cluster complex with Tuscan architecture where the wall dividing my property from that of my neighbour is a meter away from my back door. We therefore do not have proper gutters around the roofs of the structures. The natural lowest point in the neighbours’ garden where the stormwater was supposed to drain to as per Council plans has been impaired with the installtion of a jacuzzi, wooden fences and artificial grass.

    They have a patio facing the jacuzzi with two holes from the patio roof which flood with water when it rains. In 2010 holes were made in this boundary wall to take the water facing the gutters in the exact spot where the water hits the ground and these drain into my property. It was agreed that the “normal” (after the grass has become saturated) stormwater could drain into my property as a good neighbourly gesture. HOWEVER that was on the understanding that the natural grass would remain and then there was only the jacuzzi and no mention of any more construction. These holes are not made at the lowest point in the next door property and in fact are at a level point in the erf.

    In December 2014 they installed wooden fencing and in the process damaged the wall on my side. They also installed artificial grass in the path which collected the water from the holes on the patio. The spot around the actual holes has also been paved. It is now as good as a tap being turned on and left open. I have serious erosion to my property as well as big damp problems with the foundations and walls of the house. The additional construction and change in the natural grass was NEVER discussed with me.

    Is there anything I can do about this? Please let me know should you require any more information or photographs or the like.

    Thank you

    • If there are not proper gutters on the buildings in your complex, they may be contravening the National Building Regulations. I would ask a building inspector to come and look and if it is acceptable, to explain why it is acceptable. The law is clear: “The owner of any site shall provide suitable means for the control and disposal of accumulated stormwater which may run off from any earthworks, building or paving.” And Part R Stormwater Disposal of SANS 10400 gives guidelines on how builders can ensure they comply with the regs.
      Essentially your neighbour is breaking the law by draining stormwater onto your property. He/she is also liable for any damage to your wall as well as all damage caused by the water they channel onto your property. If the council won’t do anything then you should take legal action. My guess is they will also be held liable for legal costs at the end of the day.

  7. Hi, I dont know if you would be able to answer my question but here goes:

    we live on a farm close to a river. On our way home on the dirt road the dam of the farm that is higher up from us on the other side of the road over flowed just when we drove past after a short but heavy rain fall, which damaged our car to a point that it is a write-off (we had to swim to safety with our small kids).Unfortuninately it was not yet insured as we just got it.

    The run-off also flooded part of our house but there is no damage. So my question is: will we have a public liablility claim from the farm owners’ insurance who’s storm water run-off caused damage to our car? is it not their responsibility to ensure that the water that come through their lands does not endanger the people on the road or cause damage to the properties below them. The flooding is not the first but at least the third.

    looking forward to your answer!

  8. Hi Team,

    My query is very similar to the one posted by luigia. I have lived in a house for approximately three years now and this year, all of a sudden, the drainage holes in the boundary wall that drain stormwater runoff into my neighbours property appear to be blocked off. My understanding from the previous owner of the house where I now reside is that the boundary wall was built by the current neighbour some years ago. The holes that I refer to appear to be properly designed and installed drainage holes (100 mm diameter steel pipes that project through the wall and then turn downwards on the neighbours side of the wall) and I can only assume that the building plans for the wall that were submitted to the Johannesburg council showed these as weep holes. If these weep holes were approved as part of the approval process for the boundary wall, do I have any right to insist that the holes be unblocked?

    • David you have absolutely no right to drain your stormwater onto your neighbour’s property. NB the law says: “The owner of any site shall provide suitable means for the control and disposal of accumulated stormwater which may run off from any earthworks, building or paving.” Part R of SANS 10400 gives guidelines on how to do this.
      I suggest you contact the City of Jhb and ask a) if this is in the plans and b) ask for advice on how to resolve the problem.

  9. Hi there I know you have answered this question quite a few times but I need to find out how do I approach my Neighbour who has drilled a hole in my wall so that I am forced to take his storm water drainage. Shall I ask him to show me the approved plans indicating this, or shall I send him a letter to just ask him to close the hole up?
    Should I approach a lawyer?

    • Tracy this question probably comes out tops… the law is clear and it is all in the article on this page. There is no way that you have to accept his water. He must take steps to get rid of the water from his property and cannot legally simply channel it onto neighbours’ properties. Plus he cannot drill holes in YOUR wall! Get a lawyer who understands the NBR. Good luck

  10. Hi Penny, hope you can give me some advice.
    I’m living in a full title complex for the last 12 years and there is a drain hole through the wall from the start as build by the developer. Just now my neighbor decided to interfere with the hole and reduce it down to small pipe and basically blocking the hole as it would not handle the water in case of a storm and refuse to remove his blockage. In case of a storm water will flood my garage and could cause damage to the wall. There is no way I can make any plan on my side as the building level do not make is possible for me to alter the flow of water.
    What should I do?

    • The law states: “The owner of any site shall provide suitable means for the control and disposal of accumulated stormwater which may run off from any earthworks, building or paving.” So you cannot drain onto your neighbour’s property – you need to have proper drainage. The builder should have had proper drainage installed – and you may have a claim against him.

  11. Hi

    I recently purchased an off plan property. After signing and the construction going up, I see that they are installing 2 manholes in my property. The developer says he cant do anything about it, Johannesburg water decides on placement.

    If I knew about these placements I would not have purchased etc. After spending so much of money I am dissapointed.

    What can I do? Please assist urgently.

    • You can object directly to the council. The manholes are there to remove your sewage and that is where they link up to the mains. There are ways to install waste pipes without manholes and by using rodding eyes. These can be used at junctions and bends as well. Look at this picture that I took at a University of Technology plumbing training center. This is how they are taught, from the bottom of the picture up, on the left is the toilet waste pipe this joins to the main line. Bottom right is a rodding eye, next up on the left is for the waste water from a basin and at the top is a rodding eye that is situated at the bend so that any blockages can be cleared. Ask your architect to specify this method if he is allowed to.
      Sewage pipe installation

  12. we are in the dominanr tenament in a townhouse and our neighbours decided to plug the drainage holes in the wall that we share causing the water to dm up in our courtyard. as a result, the cement in our wall is becoming porous. is it legal to plug weepholes if they were approved by the council when the property was built?

    • Do you have proof that the weep holes were approved by council? I ask because it is your responsibility to dispose of water via drains and not through holes in a neighbour’s wall.

  13. Also looking at a green way to conserve water and reuse…thanks

  14. Hi Penny

    We are 3 complexes next to each other on a decline, with our complex in the middle. We are installing drains on the higher side of our complexes’ units for their drainage problems. On the lower side, the complex next to us has blocked off all the drainage holes in the wall so the back gardens are flooded in the rainy season. The actual wall is about to collapse. We are going to replace the wall out of our complex budget as the complex next door does not have funds. We want to know if it is legal for us to insist that drainage holes be put into the wall so that the water can flow through. Thanks, Venecia

    • Anyone on a lower property is not obliged to take the stormwater from the higher property. So you cannot just break holes through the wall and flood their garden. You must make provision for the water to be channelled or piped away to the street or a stormwater drain

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