How will the City of Cape Town’s Newly Introduced Water Restrictions Effect You

Water is becoming one of Earth’s most sought over natural resources, more even than land! Some have even prophesised that the next global war will be fought for it!

Why Is Cape Town Facing a Water Crisis?

To most people water appears plentiful and looking at a globe – over 70% of the Earth’s surface is covered by water – HOWEVER – not all of what is seen can be utilised for our survival. 97.5% of all the water on Earth is contaminated with salt and cannot be used for consumption without previous treatment, the remaining 2.5% is classified as fresh water and available for consumption – but held as follows:

• 68-69% is locked frozen in glaciers predominantly in the Arctic/Antarctic, Greenland and mountainous regions – some of these glaciers are exceeding 4 km in depth!
• 30% is located in underground aquifers such as
  • Guarani aquifer in South America
  • Great Artesian aquifer in Australia
  • Ogallala aquifer in Central United States
  • Nubian aquifer in Egypt and Libia
  • And numerous others worldwide
• Only 1-2% of the fresh water are found as surface water in rivers, lakes (and man-made reservoirs), wetlands etc.

Cape Town’s New Water Restrictions: Pressure Reduction Explained

So, we can understand the problem that our water reserves are finite but unfortunately the demand is increasing daily and will soon exceed the resources availability. So, what to do?

We can look at this in two ways:

• The long-term approach involving municipalities, governments, global initiatives and think tanks
• Short-term grass roots initiatives and changing consumers mind sets and ensure that the taps remain running

In this article we will concentrate on the second option and how together we can make a difference. The City of Cape Town is having to plan for an increased demand while trying to cope with a rapidly decreasing supply – the Theewaterskloof dam which supplies 51% of the water in the province has experienced a significant drop in storage levels over the last 4 months in storage levels, and as at today standing at only at 47.44% capacity as compared to 66.37% at the same time last year.

The City has therefore put forward a concise and to the point set of instructions to help reduce the severity of the threat of water rationing, with its initial concentration based on water pressure management – see www.amanzirms.co.za/blog/ , 21st February, “Why ‘MAR’ is so essential to Cape Town’s Water Survival”.

Essentially, they propose to throttle the ambient pressure the municipal feed reticulation system (previously set at 2.4-9 bar), down to a minimum of 1 bar (in the highest point of the zone) to ease water wastage due to leaks and pipe failures.

Looking carefully at the wording of the City of Cape Town’s release we can immediately anticipate some problems for certain of the cities consumers as follows:

“The city intends to keep the system pressurised to at least 1 bar at the highest point in each particular zone.”

This would mean that the consumer will have to ascertain the following to start addressing the specific problems that they would be faced with:

• In which zone is your residence sited and where are the borders
• Where in that zone is the highest point of ground level which has a municipal feed pipe running beneath it
• How deep underground is the water supply pipe laid
• Is your residence’s ground floor higher or lower than this water supply pipe at the zones highest point
• Is the building sole owned with only one tenant and how many stories does your building have
• Where are the draw off points located within the building
• Is there sufficient space outside the building (or cellar) are on top of the building to house a UV resistant polyethylene water storage tank
• If the residence has ceramic mixers, what is the minimum pressure that these can effectively operate at – older Cobra and Isca (as well as builders merchant house brands) require at least 2 bar, although many newer units can operate successfully at a pressure of at least 1 bar.

Why is it important to gather all this information?

Buildings are designed to operate with a certain “head” or height on the water column to increase pressure due to gravity which relates to each 1 m that the water must climb, the resultant reduction in pressure relates to 0.001bar (Darcy Weibach Equation). The may not be serious if the municipal supplied water is at between 4 – 6 bar – as was previously achieved in the Western Cape, but if the starting pressure has already been reduced to 1 bar, even single storey residence are designed with hot water piping and geyser situated in the roof space (most installations run both hot and cold piping down to draw off points in the roof space).

If we do a simplistic example with the following guidelines:

• Building is situated at the highest point in the zone and the water supply pipes are 0.5m below ground level
• That on average from ground floor to first floor and subsequent floors is a height of 10 feet/3m
• That no pressure loss due to friction or differing pie sizes bends or junctions on horizontal pipe runs are taken into consideration
• That the absolute minimum supplied pressure in the supply pipe is 1 bar/1000kPa

	Pressure loss at draw off point due to height in bar	Pressure at draw off point in bar
Ground Floor	0.0035	0.9965
First Floor	0.0065	0.9935
Second floor	0.0095	0.9905
Third Floor	0.0125	0.9875
Fourth Floor	0.0155	0.9845
Fifth Floor	0.0185	0.9815
Tenth Floor	0.0335	0.6650

It must also be realised that if water is drawn from a draw off point on a lower level of the building, this will also reduce both the flow and pressure of any other draw off point above it.

The obvious solution to this problem would be the addition of a holding tank/booster pump installation where water under mains pressure is stored and then in need either pumped up to secondary roof storage to gain the gravity head advantage, or directly to the individual draw off points if there are only five floors or less.

Which Cape Town Areas Are Most at Risk?

Areas like the CBD, Foreshore and V & A Waterfront, Seapoint, Greenpoint, Century City and Bantry Bay could potentially be more adversely affected as these areas as these are the areas with the majority of multi storey residential buildings.

Other water saving measures to be implemented by the City are more traditional although with much more sever punishments for transgression
These water savings include instructions, aimed at reducing the Cities consumption to below 975 million ltrs per day from around 1025 million ltrs to include – but are not restricted to:

• Take shorter showers and try to reclaim as much of the water as possible. Also
  • If you are utilising an overhead option, ensure that the rose is a water-saving 7ltr or less rated rose
  • If you are using a hand shower and rail option, again ensure that the handpiece is rate 7ltr or less, and even better to have a separate stop function
• Run washing machines and dishwashers only when completely full and preferably on economy cycles.
• Turn off all taps when not in use and ensure that there are no leaks in your whole system, especially for outside draw off points
• Watering of shrubs garden bed and lawn areas by buckets, watering cans and with a hose only if fitted with a trigger spray that automatically cuts off the water flow. Watering of gardens must be avoided during the heat of the day, can only be done before 09h00am and after 06ham to reduce evaporation

You will no longer be able to use a hose pipe to wash down driveways, pathways and patios at any time or use a hose pipe to clean motor vehicles (now to by hand with a bucket) or the outside of buildings (by compressed air or similar)

Owners with pools on their residences must ensure that they have moisture proof pool covers to minimise water loss due to evaporation and that the shell, piping and mechanical equipment has no leaks. It is also advised that the care for the pools chemical balance is closely monitored, as the owner does not want to be in the situation when due to chemical imbalances, half the pools volume must be discarded and topped up with fresh water to reset pH, counter algae infestations or correct metallic percentage volumes.

Fines for Breaking Cape Town’s Water Restrictions

The City has stated that their officials will be more active conducting property inspections with the possibility of spot fines ranging from R1500 – R5000, and of course staggered cost per kilolitre where the higher consumption market will be financially punished for over-use.

The City is calling on us all to work together to help us through these uncertain times and to prevent – or at least delay our decent to a Day Zero Scenario.

Frequently Asked Questions About Cape Town’s Water Restrictions