FEATURE 19
It ’ s all a system !
By
Rory Macnamara
Rainfall , unlike sunshine , is not something this country has a great deal of , so it is essential that we ensure every drop that falls is collected .
This feature will not go into any depth on greywater , black water or treatment but rather look at the collection of rainwater in the manner that its collection and storage is done correctly and ready for the water ’ s ultimate use .
All too often gutters and downpipes are not well maintained and can eventually cease to catch any rainwater but still allow it to pour over the gutter , creating potential problems .
It is not actually the rain that is the problem but the amount that falls in one storm . To handle this , one needs to consider rainwater catchment in the early stages of the building design to minimise damage caused in usual / normal rainy seasons . We cannot equate this feature in any manner to the unusual and disastrous flooding we have experienced and witnessed this year in some provinces .
Gutters and downpipes direct rainwater to a tank / tanks and / or into the stormwater system . The latter is a municipalities function with the stormwater being returned to water treatment plants .
All photos © Plumbing Africa Rory Macnamara
Allow water to flow away from building downhill .
Our focus is rainwater in the building where responsibility for this rainwater ’ s use is with the building owner or whomever has been appointed to maintain the building . The risk of flooding is largely removed with externally fitted eaves gutters which can generally discharge excess flow safely outside the building . This also means that by redirecting rainwater discharge away from the building one avoids the problems of surface ponding in inconvenient places , damage to foundations and the occurrence of rising damp and unsightly staining on walls .
* SANS 10400 : L Roofs - provides reference to sizing of gutters and downpipes in SANS 10400 : R Stormwater Disposal , section 4.3 Gutters , and downpipes .
Correctly positioned outlet .
Both pitched roofs and flat roofs are referenced in Part L as is waterproofing , particularly for flat roofs . Regarding flat roofs , the gutters are not used but the downpipes remain as per the engineer ’ s rational design .
** Guttering and downpipes come in seamless form and in galvanised and plastic materials . What is not always appreciated is that gutters , downpipes , angles , and outlets are a system . Like all systems they consider these factors as well as the fall , number of downpipes and
Continued on page 22 Gutter OK but needs cleaning !
September 2022 Volume 28 I Number 7 www . plumbingafrica . co . za