Integrated Rainwater Harvesting – Cape Town Case Study

While the City of Cape Town recently announced that there will be no Day Zero in 2019, informed observers of long-term weather patterns and water infrastructure planning have cautioned that it may be too soon to celebrate. Fortunately, with a myriad of rainwater harvesting options available, concerned homeowners are able to reduce the impact of this uncertainty while at the same time contributing towards long-term sustainability.

In Claremont’s Harfield Village, AWPower engineers designed and installed a comprehensive rainwater harvesting system to address the homeowner’s desire to contribute to reducing strain on the municipal infrastructure, as well as gain a degree of water independence.

The system was designed within the following specifications:

  • The home’s harvesting area consists of 100sqm of pitched tile roof and 25sqm of corrugated pergola roofing. All gutters are protected from leaf ingress with mesh guards.
  • 10kl of storage was put in place in the form of two 5kl JoJo tanks.
  • The corrugated roof’s gutters are separate from the main home gutters, with water from this roof directed into a 50 litre sump which pumps the water to the tanks using a submersible pump which automatically switches on when it rains.
  • All water is directed for initial cleaning through a first flush system with wire-brush insect guard.
  • The two tanks are interconnected and directed into the pump which serves the house through an easily cleaned cylindrical mesh filter, which protects the pump and filters further down the line from debris.
  • The system is driven by an 850W Variable Speed Drive (VSD) pump which is set to maintain a pressure of 3.0 bar into the home. When taps are opened, the pump detects and manages its output to maintain constant, ample water flow as required.
  • Water is driven by the pump through a 3-stage particle and activated carbon filter, as well as a UV filter which ensures that all bacteria are eliminated.
  • There is only a single tap in the home not served by rainwater, this tap supplying the washing machine in the scullery.
  • The home houses 2 people.

Installation was completed at the end of August 2017, whereafter the homeowner combined the new system with water saving measures such as only showering once a day, flushing toilets only when necessary, and only watering plants with grey water.

Encouragingly, rainwater supplies lasted until the end of January. Thereafter, only 6kl of municipal top-up was used until winter rains commenced towards the end of April. From May onwards, water supplies have been so plentiful that normal (pre-drought) usage patterns have been possible.

According to the happy homeowner:

“We wanted to contribute to solving the Western Cape’s water scarcity problem, while at the same time protect ourselves against Day Zero with a degree of fail-over water supply. The system AWPower installed has answered both challenges. Our pre-drought municipal usage was around 130kl/year, but the system is on track to bring us down to under 20kl/year, even with normal pre-drought usage patterns during winter. With the tanks overflowing practically every time it rains, long hot guilt-free showers twice a day in winter have become a very welcome addition to the household!”

Promotion – Modular approach to Rainwater Harvesting

Rainwater Harvesting can be installed modular and expanded over time – Start with your own Integrated Rainwater Harvesting system by taking advantage of AWPower’s promotion (VAT inclusive):

  • 5,000L JoJo for R4,900
  • Energy efficient VSD pump R7,999
  • 3-stage carbon & UV filter R12,980
  • Leaf catcher, First Flush Diverter, Water Gauge, Hatch Filter kit R2,369
  • Backflow Prevention Valve (CoCT approved) R3,739

Delivery & installation excluded
Promotion valid until 15 August 2018

 

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