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 , I am currently renting business premises and have been told that this building might be illegal as it has storm water manhole covers on the floor . Anyone know how i can find out more about the legality of this ?

    • Jeff you can either ask a qualified and registered plumber to inspect (and pay his fee), or ask the local authority to send someone out to inspect. The latter would probably be the best bet because they are ultimately the people who will take action if there are illegal elements in the building.

  2. We bought a house in Paarl. The transfer is still in the process. We have discovered that storm water from all pipes/gutters etc. just coing onto the ground. The plot has a slope – so the water is actualy flow down the neighbor’ property. Who will have to be responsible to maintain it in a right way? Am I entitled to force ex-owner to sort that out? Any suggestions please.

    • Olga you can try and hold the former owner liable, but it is likely to end up in a court case unless you stop the transfer process and use that to force him/her to take corrective action. If you weren’t aware of the situation it would be a latent defect and the previous owner certainly is liable – it’s just that it becomes a legal issue.

  3. Hi,

    I have a query, can I create a drainage systems that flows down my driveway and onto the road?


    • Terence you need a channel of some sort next to the driveway and this needs to direct the water into a stormwater drain – or the council’s stormwater system.

  4. Thanks Penny,this is just the answer I have been looking for.do you recommend that I write my neighbour a letter requesting him to install gutters and down-pipes on the said portion of roof to direct the water to ground level and if need be I will accept his ground run off water,failing which we go the legal route

    • Brian it’s your call. But (1) the regulations don’t say you have to have gutters and downpipes, just that the water must be carried away … and (2) you do not have to accept his water any which way. But if you feel you will be better off that way then make the offer. By compromising you may find that the resale value of your house decreases.
      If I was in your shoes I would demand that he directs the water to ground level to a legal drain, approved by the municipality, that carries the stormwater to the municipal stormwater drain.

  5. House A has no gutters,what is the regulation regarding the direct
    discharge of rain water over the boundary wall into my property
    causing damage and rising damp


      • Brian it sounds as if your neighbour is in breach. He isn’t allowed to discharge stormwater onto your property in any event. My opinion is that he is liable to damage to your walls. But I am not a lawyer, just an educated layperson. If I was in your position I certainly wouldn’t accept what he is doing. Contact the building inspectorate at your local authority and ask them to help you. If they can’t or won’t – then you will probably need to enlist the help of an attorney. Good luck.

  6. What are the rules and regulations regarding direct discharge of rainwater from a roof (no gutters)into adjacent property creating damage to walls and rising damp?

    • Brian, please read all the comments and replies at the bottom of the page. I am pretty sure we have covered this already. Basically this in not a natural path of water and so your neighbour (I presume) needs to take steps to channel the stormwater into an appropriate drain.

  7. Hi there,

    We have recently bought a Sectional title unit in Benoni. The unit is a first floor unit which makes use of a centralized staircase which leads onto a landing supplying access to the 3 first floor units.

    The staircase has a full IBR roof on it but the staircase landing itself hasn’t got a full roof on it resulting in rainwater and roof condensation dripping directly onto the floor resulting in access water being left on the floor.

    Upon discussing this with the developer they confirmed that they would simply install a gutter that would lead the water away from the edge of the roof onto the floor but instead onto the stair cases roof.
    This was not done…….instead they installed a 40cm piece of gutter with a down pipe that leads the water onto the first floor landing area, resulting in more water being dumped onto the floor causing a slippery hazard as well as possible future damp and water damage.

    Where can we find in the act the piece that covers this scenario described ?

    • Clearly this is not legal. But I think you need to do more than find legislation to prove this.
      In terms of the National Building Regulations, Drainage is covered in Part P of SANS 10400, but it doesn’t go into gutters and downpipes. This is covered in Part R, Stormwater Disposal which, in general terms, address how stormwater needs to be disposed of.
      First of all, a qualified registered plumber should have been appointed to do this job. But this sounds as if it could also be a design issue with safety implications.
      If I were you I would contact the chief building inspector at your local authority and ask them to do an inspection.

  8. My Neighbour has been doing extensive building and paving etc to accommodate a B&B and a second dwelling. He has a sloped property and has obviously experienced water drainage problems with the Neighbour below his property. I say this because he has built structural supports to support that wall and it is downside from his property. He also appears t be diverting water from that boundary to my boundary.

    I now notice that he has punched two holes in my/our adjacent concrete wall to allow run off. We have never in 30 years ever been on the receiving side of any run off from his property as we are more adjacent than below his property. I contend that he cannot divert storm water onto my premises and that his building plans must deal with water drainage. Who do I approach?

    • Peter, Contact the chief building inspector at your local municipality/council.
      The law (The National Building Regulations and Building Standards Act) states:
      R1 Stormwater Disposal Requirement
      (1) 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.
      (2) Such means of stormwater disposal may be in addition to or in combination with any drainage works required in terms of regulation F4(2). see below
      (3) The requirements of subregulation (1) shall be deemed to be satisfied where such means of stormwater disposal is provided in accordance with SANS 10400-R: Provided that where a local authority is of the opinion that the conditions on any site render it essential for stormwater disposal to be the subject of an acceptable rational design prepared by an approved competent person, such local authority shall, in writing, notify the owner of such site of its reasons for the necessity for such design, and may require such owner to submit for approval plans and particulars of a complete stormwater control and disposal installation for such site and for any building erected thereon, based on such design.”
      SANS 10400-R is very short – eight pages in all. The requirements are dealt with in three parts, General, Stormwater & Disposal, Gutters & Downpipes. These describe acceptable ways of dealing with storm water – and channeling it onto a neighburs property is NOT an option.

      F4 Preparation of Site (this is in Part F, Site operations)
      (2) Where any site upon which any building is to be erected is waterlogged, seasonally waterlogged or saturated, or where any building is to be so situated that water will drain naturally towards it, drainage shall be provided to direct such water away from such site or building to a stormwater drain or to dispose of it in some other safe approved manner.

    • Peter

      Re the drainage issue from your neighbours site that is above yours.

      Drainage of surface water is a bit more complicated as laid put in SANS 10400 part R.

      Below is an extract from a property law course I did a while back with the relevant cases and decisions listed: (Please note, I am not lawyer!)

      “An owner of property has the right to discharge the natural flow of water onto adjoining property, and the owner of the adjoining property is under an obligation to receive this flow.

      Thormahlen v Gouws 1956(4) SA 430 A (case)

      This right is limited to the discharge of natural flow in its natural course, so the owner may not erect an artificial construction which concentrates or increases the natural flow onto adjoining property. Similarly, the owner may not discharge ‘alien’ water onto the property of his neighbour.

      New Heriot Gold Mining Co Ltd v Union Government 1916 AD 41 5 (case)

      The owner may discharge more than the natural flow of water in the following situations:
      -under contract
      -under servitude
      -through immemorial user
      -under the authority of statute
      -in the course of reasonable natural cultivation

      Re ‘reasonable natural cultivation’ see:
      Benoni Town Council v Meyer 1959(3) SA 97 W (case)

      The aggrieved owner has a number of remedies available:

      These remedies are divided up according to the usage of the property. For this purpose property is divided into two usages: rural and urban. The classification is based on the size and usage of the property, rather than on its location. Thus large property with limited usage will be regarded as rural, whereas a smaller property with intense usage would be regarded as urban. “

      • J – Diverting water is not allowing the water to flow along its NATURAL course. Peter’s neighbour is way out of line!

      • Hi All,
        I have found the relevant clause in the “Johannesburg Town Planning Scheme 2011”. And it states (in full) under section 14 (General conditions applicable to all erven) – Paragraph 2: “Where, in the opinion of the Council, it is impracticable for stormwater to be drained from higher lying erven direct to a road, the owner of the lower lying erf shall be obliged to accept and/or permit the passage over the erf of such stormwater: Provided that the owners of any higher lying erven, the stormwater from which is discharged over any lower lying erf, shall be liable to pay a proportionate share of the cost of any pipe line or drain which the owner of such lower lying erf may find necessary to lay or construct for the purpose of conducting the water so discharged over the erf.”
        I am still investigating if other Local Authorities follow the same or similar rulings. I will post the findings here as soon as I have these.

  9. Hi
    my neighbour’s property is higher than ours by approximately a metre and they had a brick missing in the boundary wall which allowed their storm water to pass from the front of their property into the front “verge” of our property.
    We recently built a new front road facing boundary wall and established that a portion of our property was on the “verge”. Basically the fence was previously built well inside our property. When we completed the new wall on our true road-facing boundary, the hole in the shared boundary wall was plastered in. They have asked us to reopen this hole. Are we required to do this and allow them to divert all their storm water into our front yard.
    Also the shared boundary wall is in a seriously bad condition due to a creeper that they have growing from their side. There is also evidence of water damage/erosion on the wall as the paint has peeled off and the wall is powdery on our side. We have kept the wall bare on our side.
    Are they supposed to have a proper drainage system in place?

    • That missing brick story is illegal for starters! And no you do not have to oblige. And yes they should have a proper drainage system. BTW the reason the wall is well into your side might be due to extensive foundations – which is a good thing. We have just done a piece on boundary walls that we will be posting in the next day or so – if SEACOM gets its act together. Check back for the new post.

  10. Please can you advise what is the legal distance for a dwelling (granny flat or garage ) to be from your neighbours boundry wall?

    Many Thanks

  11. A stormwater drain has been blocked on our neighbour’s property which
    means that every time it rains, stormwater dams up on our side of the
    Our neighbour says that the pipe was blocked by the previous owners
    and refuses to reopen it. He also says that as he is on a higher erf
    he does not have to take our water. This is absurd as we are on a hill
    and it is patently obvious that his property is lower than ours.
    Can I open weep holes in our wall in order to force him to take some

    • John, you cannot legally open up weep holes in the wall. Stormwater must be discharged into a drain approved by the local authority. If the pipe you are referring to was part of the storm water system the municipality approved, then your neighbour will have to unblock the pipe. Perhaps the storm water drainage issue was part of a dispute between previous property owners?
      I have added to the article on this page, and you will see that people cannot simply discharge water onto an adjacent site. Not knowing the exact layout of the properties to the road and so on, it’s difficult to know what to suggest. Your best bet is to ask your local authority for advice.

  12. Good morning, I hope you can help. I reside in Roodepoort. What can I
    do when my neighbour washes his driveway and paving down regularly and
    the waste water then runs onto my property via the opening for the
    drainage of storm water in the boundry wall. My property is lower than
    the neighbour’s, and I know that stormwater must have free flow,
    however can he just use the excuse that as water flow down, he has the
    right to dispose of his waste water onto my property. My plants and
    grass are now starting to die as a result of the excess water and
    chemicals/soap in the waste water.
    I have tried to reason with him, but to no avail.
    Hope you can help.

    • I am not sure when you posted your comment Anton, but I recently updated this page. If you want more detail, you can access SANS 10400: Part R Stormwater Disposal from an SABS library.

  13. I am a trustee of a sectional title complex in the E Cape. With all
    the recent heavy rain parts of the common property have been flooded
    by storm water emanating from the Municipal system which ends suddenly
    with an open pipe at the boundary of our land. The Municipality
    contends that it was the responsibility of the developer of our
    complex to have installed a storm water system to connect into the
    muncipal system which would dispose of “their” water (into the sea).
    Is the municipality correct ? This means running a 450 mm concrete
    pipe over a distance of 130 meters which is expensive and far in
    excess of the requirement to simply drain syrom water otherwise
    accumating on our property. Please advise. Thank you

    • Yes Errol, the municipality is correct. I have recently added more information to this page – it may be helpful to you. If you need more detail, you can access SANS 10400: Part R Stormwater Disposal from an SABS library.

    • Dear Errol – I am trying to contact you about your property in Cape Town. Please can you get in touch

  14. Hello

    My property is naturally lower than my neighbours. They recently paved
    their entire yard and made the lowest point at the back of their
    property where they allow all their stormwater to flow through a
    drainage panel in the boundary fence into my back yard. Is this legal
    and allowed? I now have to do some work to my levels to allow the
    water to drain away.

    Is this allowable? Should they have asked me or the municipality
    before they paved their yard?


    • Viroshka I have added to the article on this page – and have recently answered several queries very similar to yours. They cannot simply allow stormwater to flow into your yard. While they did not need permission from the municipality or from you to pave their yard, it is their responsibility to ensure that stormwater is channeled to a suitable storm water drain.

  15. My neighbour, whose property level is above mine has no drainage for their rainwater downpipes, all the water from their roof runs over their driveway, down a once grassy bank and into my property. Their bank is being undermined and so is mine, to the point that there is a gap under the fencing where rocks and sand have been washed away. All this mud and water flows down my path and into my pool every time during our Spring rains and Storms. I have tried to dig trenches on my side of the fence to control the water but unfortunatly they get filled up with mud very quickly. Are they obliged to have some sort of drainage system in place or am I fighting a losing battle?

    • They absolutely are required to have adequate drainage. In fact the SANS for drainage are very strict and specific.
      I suggest that you call the local council and ask for a building inspector who deals with plumbing issues to come and assess the problem.

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