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The ins and outs of above-ground drainage


By: Kelly-Ann Prinsloo

Sanitation is vitally important to health and wellness of human beings and adequate drainage installations play a big role in that. Every year, millions of people around the world become ill and die simply because they do not have a safe, clean place to do that thing we all must do – go to the loo. According to Statistics South Africa’s 2013 general household survey, 89.9% of South African households have access to piped water, while only 77.9% have access to improved sanitation.

One of the most important factors of preserving and improving the health and wellness of people around the world is drainage. Safe, reliable, adequate drainage has always been a big part of any sanitation system.

In this feature, which follows on from the ‘below-ground drainage’ feature published in the March 2016 edition of Plumbing Africa, we take a loo at the fundamental differences between above- and below-ground drainage, and what plumbers should keep in mind when dealing with above-ground drainage.

Above and below
One of the most obvious difference between above- and below-ground drainage is that one is installed about the ground and one below. This may seem self-explanatory, but each type of drainage comes with its own set of complications.

Louis Kruger, technical support specialist at Marley Pipe Systems, says, “The conditions in which the pipe system is to be installed is important; above-ground conditions differ from below-ground conditions. An above-ground system must be able to withstand harsh weather conditions like sun, wind, rain, and hail. The biggest of the abovementioned conditions is UV rays. To protect it against UV rays, the product must be manufactured with materials that will provide adequate protection.”

Renier Snyman, technical and product manager at DPI Plastics, agrees. “In South Africa, we plumb on the outside of the wall, which means the pipes and fittings are exposed to the elements. They must be UV-resistant, they must be able to operate at low temperatures and, because above-ground drainage systems are on the outside of the wall, they form part of the aesthetics of the house.”

Snyman adds that, in below-ground installations, what is most important is the stiffness of the pipe because, if a section of the pipe collapse, it will cause a major blockage. Stiffness isn’t as important with above-ground installations because the pressure that exists below-ground is not a factor above-ground.

Kruger adds, “The installer must ensure that the installation is correctly and neatly installed to the approved drawings for the specific installation.”

The standard that deals with drainage is South African National Standard (SANS) 10400-P, which was issued in terms of the National Building Regulations (NBR) and Building Standards Act, includes many important definitions for plumbers and installers to take note of. One of the most important, however, is that it defines a competent person as ‘a person who is qualified by virtue of their education, training, experience and contextual knowledge to make a determination regarding the performance of a building or part thereof in relation to a functional regulation or to undertake such duties as may be assigned to them in terms of the NBR’. Competence is an intricate and hotly-debated issue so it is vitally important than any plumber or installer undertaking to install a drainage system, or any plumbing installation, is aware of the standards and follows them.

In terms of the requirements of sanitation systems, SANS 10400-P (Annex B) states that sanitation systems shall, with an appropriate degree of reliability over the lifetime of a building:
a) Provide for privacy and protect the user and others from the weather when in use.
b) Prevent soil, garbage and other foreign materials from entering the system by the action of wind or animals.
c) Not present or cause a nuisance or a danger to health as a result of their use and operation.
d) Withstand all actions to which they are likely to be subjected to.
e) Not leak soil water into the surrounding soil, if buried.
f) Be compatible with the water supply.
g) Be capable, where required, of carrying the design hydraulic load, and drain and discharge into a municipal sewer system, a common drain or other sewage disposal system, or dispose of effluent in a safe and inoffensive manner.
h) Not contaminate clean water supplies or ground water to the extent that such contamination poses a health risk.
i) Be easy to use, clean and maintain.
j) Be able to accommodate and dispose of commonly-used cleaning materials.
k) Satisfy nominated parameters, depending upon the nature of the system.

All sanitation systems must satisfy the above requirements to be deemed compliant.

Sanitation systems are not very complicated in comparison to the water side of plumbing and heating, but for public health reasons there are strictly laid-out rules that stipulate what should be installed and how.

What is most important is that you, the plumber, understand the benefits and limitations of the pipe you plan to use, and that you follow the standards as closely as possible, in order to provide safe and reliable sanitation systems for the public to use and enjoy.

*To read more about drainage, refer to the 'below-ground drainage’ feature in the March 2016 edition of Plumbing Africa.

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