Stormwater Disposal
Stormwater Disposal-Part R, What the Regulations Say
Property owners are responsible for the removal of stormwater 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 is 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 R977.50 incl. VAT.(This is an old price please co to the SABS and check)
SANS 10400, Part R deals with all types of stormwater disposal, including rainwater 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:
- Major stormwater systems that cater for severe, infrequent storm events
- 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 stormwater 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 storm water drains that are either on the surface or below-ground, or channels – depending what 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 neighbouring 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 stormwater 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 stormwater drain, or somewhere that it can be disposed of in some other safe and approved manner.
Note that these requirements 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 stormwater 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 stormwater should be built.
- SANS 10120 – A Code of practice for use with the above, including:
- Part 2: Project specification Section LE: Stormwater drainage
- Part 3: Guidance for design Section LE: Stormwater drainage
- Part 4: Typical schedule of quantities Section LE: Stormwater drainage
- Part 5: Contract administration Section LE: Stormwater drainage
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Hi, I’m about to start building my house. The issue I have is the following. I Have the lowest level property. The guy next door made a hole in his wall for his drainage that goes into my property. The thing is, the stormwater of the two properties next to him goes into his property. Effectively my property would carry stormwater of all 3 properties next to me. I Bough a stand next to the boundary wall of the estate, the other issue is that the road on the other side of the boundary is higher than my stand so I can’t even drain all this water out there. According to my knowledge I must carry my neighbors stormwater, but only his. Not all three properties. I have no idea what to do. Please help
Anoop, I would refuse them access and notify the municipality that you are doing so because of the fact that they have ignored the municipality’s non-compliance notifications. Further, I would demand that the municipality take urgent steps to have the illegal building demolished. At the moment it seems that you have the upper hand in terms of the stormwater drain… Probably the people at the municipality who are making these recent demands are not aware of the previous actions. Go into their offices with all the details and any proof you have, and demand to talk to a senior person. From your email address, I’m wondering where you work 🙂
The land adjacent to mine (residential) was re-zoned to religious site. I had given the owners (Trust) permission to build on the boundry line in terms of the approved plans. However they have built thus far not in accordance with the approved plans. The approved plans showed an open basement parking. However, they have deviated in that they built boundary walls with windows and converted this into a hall. My home is affeced by the light & noise eminating from the functions they have during weekend that goes late into the night/ next morning.Their stromwater is draining into my backyard.The building remains incomplete from 2004. After lodging numerous complaints for years with the Municipality, the municipality had issued a letter of non-compliance and summons twice, and no further action was taken by the municipality.
Now the municipality has notified me that according to the National building regulation I am oblidged to give the Trust permission to construct a storm water drain over my property to be deposited into the bottom stream at their cost which the municipality will oversee.
Do i have a right to have them remove the boundary walls with widows and deny them use of my property to construct a storm water drain?
Alleen, Part R of SANS 10400 covers stormwater disposal. I don’t have a copy of that available to me right now, so can’t give you the wording, but you can buy a copy from the SABS online store, or have a look at it at one of their libraries. However the legislation states 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.” If necessary, the local authority may (according to the Act) insist on a “rational design prepared by an approved competent person” e.g. an engineer. They may also insist on plans for this. Part R – which is the “deemed to satisfy” part of the regs – gives guidance on how stormwater should be disposed – e.g. gullies, drains, downpipes and gutters etc
So you will see that the owner of a property is obliged to take care of his/her own drainage of stormwater – and this does NOT mean that you must expect your neighbour to take the flow of water onto their property (unless there is a registered servitude for this purpose). There is no law that states neighbours must share costs of anything.
Subject:
Storm water management
Message:
Good Day. I would like to see the wording of the law that states that a neighbour whose property is lower than yours are not allowed to prohibit the natural flow of storm water. Also is there a cost sharing
implication if a drainage system must be put in place to manage the water between to neighbouring properties?
Subject:
Pipes underground
Message:
Recently I installed a Jojo Tank and pump to increase water pressure. The installer ran the water pipes just about 15 – 20 cm below the garden lawn. What is the regulation regarding the depth water pipes and underground electricity pipes/conduits? Kindly direct me to relevant literature. Thanks and regards. Ahmed
Aj you are correct in your assumptions. I suggest you contact the local authority and report this to them.
Juanita, People are not allowed to simply drain their swimming pools onto other people’s properties. It isn’t a building regulation issue, though drainage is. It needs to be drained into a drain or directly into the road. If he is difficult to talk to – write a letter that states he has no right to do this and that you are going to hold him liable for damage if he does it again – and public nuisance since he regularly renders your garden unusable. If he doesn’t stop then you may need to pay a lawyer to write a letter for you. Nobody needs a neighbour like that!
My neigbor drains his pool every month all the water into my yard, not just backwash, I am talking about draining his pool, he floods my braai area and my grass is completely muddy from this. He is very difficult to talk to, what can I do .
Good day,
About a year ago my house was build with proper stormwater drainage pipes in the boundary walls. My neighbour started building about 4 months later when I started. Since I am at work during the day, I have not really noticed any problems with draining of excess water, until recently. What I noticed was that the paving of my neighbours house blocked one of the stormwater drainage pipes with about 10% of the pipe open for draining. This unfortunately results in a very slow draining on my side to such an extend that the water level builds up higher than the pipe. Speaking under correction, blocking of stormwater draining pipes is not allowed and these pipes should be kept open at all times? How do I proceed with this issue and is this semi-blocking legal?
Thank you.
Hi Kobus, Here is an extract from the Jhb bye-laws:
“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”
All the municipalities will follow the same bye-laws, so PE wil be the same. You can call the local building inspector and report your neighbour for violating the law.
I stay in Port Elizabeth <
I am staying in the same house for 12 years, its a panhandle property and my storm water have been draining into my one neighbour property.
A year ago new owner build on and we have discussed the "drain hole", as he want to put a floor down. I have agreed to put a pipe down at my cost so to control the water and the floor can go on top.
Two weeks ago I spotted the hole was completely closed of with concrete , spoke to another neighbour and she had the same issue.
If it rain now my house will be flooded, what to do??
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.
Peter, IOPSA’s technical advisor, Martin Coetzee (who works for Cobra Watertech) is incredibly knowledgable. Why not give him a call? Or ask Iopsa to pass on your message and get him to call you. Good luck
Peter, I would think that “lower” means lower anywhere or overall. i.e. Parts could be even lower than on the boundary – or higher on the other side.
Nobody has the right to make a drainage hole in your wall without your permission.
But you probably need a lawyer to do a proper interpretation of the bylaws. You might also call the SA Institute of Plumbing (you’ll find regional contact numbers on their website) and ask to speak to one of their committee members who can advise you. In addition to plumbing and drainage issues detailed in SANS 10400 (the National Building Regulations) there are a number of other Standards that deal with drainage.
Hi Penny, I am in a complex and adjacent stand is being developed. It has a close to 60% coverage ratio and I guess about 40% of the remaining land will be paved. The developer has informed me that approx 2/3 of storm-water will be directed to the road via gutters etc. The stand slopes back from the road and, for last 1/3, the developer plans to channel any overflow into adjacent stands including mine. Mine may be marginally lower (a couple of cms) at the boundary, but that is the low point of my stand so storm water could pool up to an estimated 15 cm. I have asked the developer to use french drains etc to improve the stand’s water carrying capacity but have not met any enthusiasm.
Our suburbs by-laws do indicate that a lower lying stand should take overflow with the higher stand contributing to the cost of any extra drainage requirements on the lower stand.
Does ‘lower’ mean lower at the boundary or lower on average than the other stand’s boundary?
Does of the owner, have a unilateral right to make a drainage hole in my wall?
How far does the owner have an obligation to mitigate storm water run off via, e.g. french drains?
Is there any guidance on what ‘contribute’ means?
Lastly, what are my obligations?
I’d appreciate your suggestions and guidance. Thanks v much for your help
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 ?
Thank you Penny!
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.
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.
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.
Hi,
I have a query, can I create a drainage systems that flows down my driveway and onto the road?
Thanks
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.
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.
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